Elbow Injuries Workers Compensation Gene

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Elbow Injuries – Worker’s Compensation General Guidelines

Table of Contents

1. Ulnar Neuropathy at the Elbow

2. Radial Nerve Entrapment

3. Median Nerve Entrapment

Effective Date January 1, 2010, modified January 22, 2015 Page 1

Work-Related Ulnar Neuropathy at the Elbow (UNE)

Diagnosis and Treatment*

Table of Contents

I. Surgical Criteria

II. Introduction

III. Establishing Work-Relatedness

IV. Making the Diagnosis

A. Symptoms and Signs

B. Electrodiagnostic Testing

C. Other Diagnostic Tests

V. Treatment

A. Conservative Treatment

B. Surgical Treatment

VI. Return to Work (RTW)

A. Early Assessment

B. Returning to Work following Surgery

VII. Electrodiagnostic Worksheet

*This guideline does not apply to severe or acute traumatic injury to the upper extremities

Med

ical T

reatm

ent G

uid

elines

Wa

shin

gto

n S

tate D

ep

artm

ent o

f La

bor a

nd

Ind

ustries

Effectiv

e Date Jan

uary 1

, 20

10

, up

dated

Janu

ary 2

2, 2

01

5

Page 2

I. U

LN

AR

NE

UR

OP

AT

HY

AT

TH

E E

LB

OW

SU

RG

ICA

L C

RIT

ER

IA

SU

RG

ICA

L

TR

EA

TM

EN

T

AN

D if th

e dia

gn

osis is su

pp

orted

by th

ese clin

ical fin

din

gs

CO

NS

ER

VA

TIV

E

TR

EA

TM

EN

T

SU

BJE

CT

IVE

O

BJE

CT

IVE

D

IAG

NO

ST

IC

Sim

ple d

ecom

pressio

n

Surg

ery sh

ould

inclu

de

explo

ration o

f the u

lnar

nerv

e thro

ughout its

course aro

und th

e

elbow

, and release o

f

all com

pressiv

e

structu

res. Com

plete

release may

require

nerv

e deco

mpressio

n at

multip

le sites and m

ay

also req

uire Z

-

length

enin

g o

f the

flexor p

ronato

r orig

in.

Pain

or d

ysesth

esias in

the rin

g an

d sm

all

fingers (4

th or 5

th dig

its)

often

coupled

with

pain

in th

e pro

xim

al med

ial

aspect o

f the elb

ow

.

Note: P

ain o

r

paresth

esias may

worsen

at nig

ht.

Dim

inish

ed sen

sation o

f

ring an

d little fin

gers an

d

med

ial aspect o

f the h

and

OR

Pro

gressiv

e muscle

weak

ness w

ith in

ability

to

separate fin

gers, lo

ss of

pow

er grip

and p

oor

dex

terity

OR

Atro

phy o

f uln

ar intrin

sic

muscles o

f han

d

OR

Claw

ing co

ntractu

re of rin

g

and little fin

gers

OR

Fro

men

t’s sign

Electro

diag

nostic stu

dies are req

uired

to

objectiv

ely co

nfirm

the d

iagnosis o

f UN

E.

Electro

diag

nostic criteria are as fo

llow

s (at least

two o

f the criteria sh

ould

be m

et):

1. S

low

ing o

f above elb

ow

(AE

) to b

elow

elbow

(BE

) nerv

e conductio

n v

elocity

to less th

an 5

0

m/s in

either A

DM

or F

DI.

2. F

ocal slo

win

g o

n in

chin

g stu

dies o

f the u

lnar

nerv

e across th

e elbow

, defin

ed as a laten

cy

differen

ce exceed

ing 0

.7 m

sec across a 2

-cm

segm

ent (o

r 0.4

msec acro

ss a 1-c

m seg

men

t).

3. C

om

pound m

uscle actio

n p

oten

tial (CM

AP

)

amplitu

de d

ecrease of >

20%

betw

een A

E an

d B

E

wav

eform

s†

4. C

MA

P d

uratio

n in

crease of >

30%

betw

een A

E

and B

E w

avefo

rms*

*F

or electro

myograp

hers: fo

r findin

gs 3

and 4

,

and p

articularly

when

there is am

plitu

de d

rop

betw

een w

rist and B

E, th

e presen

ce of M

artin-

Gru

ber an

astamosis m

ust b

e exclu

ded

as a cause

of th

ese findin

gs.

At least 6

week

s* o

f

conserv

ative care su

ch

as:

M

odified

activities an

d

avoid

ing

leanin

g o

n

elbow

s

S

plin

ting to

limit flex

ion at

elbow

P

addin

g to

limit p

ressure

on elb

ow

*In

the case o

f clear

moto

r deficit, th

e 6

week

s conserv

ative

care is not req

uired

.

* In

unusu

al circum

stances, a p

atient m

ay h

ave ap

pro

priate sy

mpto

ms an

d ab

norm

al ED

S w

ithout o

bjectiv

e physical fin

din

gs.

AN

D

AN

D

AN

D


Work-Related Ulnar Neuropathy at the Elbow (UNE)

Diagnosis and Treatment

The medical treatment guidelines are written from a clinical perspective, to guide clinical care.

Providers should consult the Medical Aid Rules and Fee Schedule (MARFS) for documentation

and coding requirements.

II. INTRODUCTION

This guideline is to be used by physicians, Labor and Industries claim managers, occupational nurses, and utilization review staff. The emphasis is on accurate diagnosis and treatment that is curative or rehabilitative (see WAC 296-20-01002 for definitions). An electrodiagnostic worksheet and guideline summary are appended to the end of this document.

This guideline was developed in 2009 and updated in January 2015 by Washington State's Labor

and Industries’ Industrial Insurance Medical Advisory Committee (IIMAC) and its subcommittee

on Upper Extremity Entrapment Neuropathies. The subcommittee presented its work to the full

IIMAC, and the IIMAC made an advisory recommendation to the Department to adopt the

guideline. This guideline was based on the weight of the best available clinical and scientific

evidence from a systematic review of the literature and on a consensus of expert opinion. One of

the Committee's primary goals is to provide standards that ensure a uniformly high quality of

care for injured workers in Washington State.

Ulnar nerve entrapment (UNE) occurs most commonly at the elbow due to mechanical forces

that produce traction or ischemia to the ulnar nerve. A differential diagnosis for UNE includes

cervical radiculopathy, brachial plexopathy and compression of the ulnar nerve at the wrist[1]

.

Entrapment may also occur from soft-tissue structures such as tumors or ganglions, bony

abnormalities such as cubitus valgus or bone spurs, or subluxation of the ulnar nerve over the

medial epicondyle with elbow flexion[3]

. A tardy ulnar nerve palsy may be seen in association

deformities of the elbow secondary to a supracondylar fracture of the humerus. This may occur

when the ulnar nerve becomes entrapped by scar tissue. This may produce anterior displacement

of the nerve with elbow flexion, which may then spontaneously reduce back into the ulnar nerve

groove with elbow extension. Potential sites of UNE include Osborne’s ligament at the cubital tunnel, the arcade of Struthers,

the medial intermuscular septum, the medial epicondyle, the flexor-pronator aponeurosis, and

rarely an accessory muscle, the anconeus epitrochlearis[2]

.

In general, work-relatedness and appropriate symptoms and objective signs must be

present for Labor and Industries to accept UNE on a claim. Electrodiagnostic studies

(EDS), including nerve conduction velocity studies (NCVs) and needle electromyography

(EMG), should be scheduled immediately to corroborate the clinical diagnosis. If time loss

extends beyond two weeks or if surgery is requested, completion of EDS is required and

does not require prior authorization.


III. ESTABLISHING WORK-RELATEDNESS

Work related activities may also cause or contribute to the development of UNE. Establishing

work-relatedness requires all of the following:

1. Exposure: Workplace activities that contribute to or cause UNE, and

2. Outcome: A diagnosis of UNE that meets the diagnostic criteria under Section III, and

3. Relationship: Generally accepted scientific evidence, which establishes on a more

probable than not basis (greater than 50%) that the workplace activities (exposure) in an

individual case contributed to the development or worsening of the condition (outcome).

Although the exact incidence and prevalence are uncertain, UNE is second only to carpal tunnel

syndrome as the most common peripheral nerve entrapment. From 1995-2000, approximately

2800 claims for work-related UNE were reported to the Department of Labor and Industries

(L&I)[4]

. A quarter of these patients received surgical treatment while the remainder was treated

conservatively. Time loss payments were paid to 93% of the surgery group and 61% of the

conservatively treated group.

Certain work-related activities have been associated with UNE. Activities requiring repetitive or

sudden elbow flexion or extension, intensive use of hand tools, or repeated trauma or pressure to

the elbow[5-7]

. Jobs where these activities occur may include but are not limited to the following:

Lifting Leaning on elbow(s) at desk or work bench

Working in tight places Shoveling

Digging Hammering

Using hand saws or large power machinery Operating boring and punching machines Several occupations have been associated with UNE. This is not an exhaustive list and is meant only as a guide in the consideration of work-relatedness.

[3, 5]

Carpenter Painter Glass cutter Musician Seamstress Packaging worker Assembly line worker Shoe and clothing industry worker Food industry worker

IV. MAKING THE DIAGNOSIS

A. SYMPTOMS AND SIGNS A case definition of confirmed UNE includes appropriate symptoms, objective physical findings

("signs"), and abnormal electrodiagnostic studies. A provisional diagnosis of UNE may be made

based upon appropriate symptoms and objective signs, but confirmation of the diagnosis requires

abnormal EDS.

The primary symptom associated with UNE is diminished sensation or abnormal unpleasant

sensation (dysesthesias) in the ring and small fingers (4th

or 5th

digits), often coupled with pain in

the proximal medial aspect of the elbow[7]

. Motor symptoms may include progressive weakness,


with inability to separate fingers, loss of power grip, and poor dexterity. Non-specific symptoms,

(e.g., pain without sensory loss; “dropping things”) by themselves are not diagnostic of UNE.

Symptoms of UNE may worsen at night. Symptom provocation has been described with Tinel’s

sign (tapping over the cubital tunnel), or by sustained (sixty seconds) elbow flexion with or

without manual compression of the ulnar nerve at or proximal to the cubital tunnel[8]

. Alone,

these findings are neither sensitive nor specific for the diagnosis of UNE.

Objective findings on physical examination should be localized to muscles supplied by the ulnar

nerve (Table 1) or sensory impairment in an ulnar distribution. Motor deficits include weakness

of intrinsic hand muscles, which can be demonstrated with Froment’s sign (activation of flexor

pollicis longus to compensate for weak adductor pollicis). To perform this test, the patient is

asked to pinch a piece of paper between the tip (not pad) of the thumb and the tip (not pad) of the

index finger. The tester pulls the paper out from between the fingers, asking the patient not to let

go. Weakness of the ulnar innervated adductor pollicis muscle (or positive Froment’s sign) is

present if the patient cannot maintain a tip-to-tip pinch and instead resorts to a pad-to-pad pinch.

In more advanced cases, intrinsic muscle atrophy becomes visibly evident (e.g. 1st dorsal

interosseous). In severe cases, hand opening will reveal a characteristic “ulnar claw” posture,

with hyperextension of the metacaropophalangeal joints and flexion of the interphalangeal

joints[2]

. (This should not be confused with the median neuropathy “benediction” sign seen with

hand closing.) Ulnar sensory impairment can be demonstrated using Semmes-Weinstein

monofilaments and should be localized to the ring and small finger and ulnar aspect of the hand.

There appears to be a high frequency of diagnostic imprecision for cases handled within the

workers’ compensation system. In the general population, UNE typically occurs as an isolated

mononeuropathy, with co-incidence of UNE and carpal tunnel syndrome being relatively

uncommon. However, the experience of L&I shows that approximately 60% of UNE surgery

patients had a concomitant diagnosis of carpal tunnel syndrome, usually made prior to a

diagnosis of UNE[4]

. Every effort should be made to objectively verify the diagnosis of UNE

before considering surgery.

Table 1. Muscles Innervated by the Ulnar Nerve

In the forearm, via the muscular branch of the ulnar nerve

Flexor carpi ulnaris

Flexor digitorum profundus (medial half)

In the hand, via the deep branch of the ulnar nerve

hypothenar muscles

-Opponens digiti minimi

-Abductor digiti minimi

-Flexor digiti minimi brevis

Adductor pollicis

Flexor pollicis brevis deep head

3rd

and 4th

lumbrical muscles

Dorsal interossei

Palmar interossei

In the hand, via the superficial branch of the ulnar nerve

Palmaris brevis


B. ELECTRODIAGNOSTIC STUDIES (EDS) i. Nerve Conduction Velocity Electrodiagnostic studies can help to objectively locate, confirm, and quantify the severity of

ulnar nerve compression. Nerve conduction velocities (NCV) are measured across the elbow

with the ulnar-innervated hand intrinsic musculature (abductor digiti minimus or first dorsal

interosseus muscles) used for motor velocity determination. Parameters for accurate testing

include moderate flexion of the elbow (70°- 90°) and a consistent and documented distance

across the elbow (at least 5-6 cm with digital storage oscilloscope or 10 cm with older

electrodiagnostic equipment)[9-11]

.

There must be evidence of ulnar nerve demyelination with or without axon loss to confirm a

diagnosis of UNE and should include at least two of the following motor nerve conduction

abnormalities:

1. Slowing of above elbow (AE) to below elbow (BE) nerve conduction velocity to less than

50 m/s in either the abductor digiti minimi (ADM) or first dorsal interosseous (FDI).

2. Focal slowing on inching studies of the ulnar nerve across the elbow, defined as a latency

difference exceeding 0.7 msec across a 2-cm segment (or 0.4 msec across a 1-cm

segment)

3. Compound muscle action potential (CMAP) amplitude decrease of >20% between AE

and BE waveforms*

4. CMAP duration increase of >30% between AE and BE waveforms*

*For electromyographers: for findings 3 and 4, and particularly when there is an

amplitude drop between wrist and BE, the presence of Martin-Gruber anastamosis must

be excluded as a cause of the findings.

To exclude the presence of polyneuropathy as a cause of the abnormalities described above,

evaluation of another motor nerve must be normal.

Ulnar sensory electrodiagnostic abnormalities alone are considered to be nonspecific and

nonlocalizing and hence cannot alone be used to confirm a diagnosis of UNE. Amplitude of the

sensory response is non-localizing and velocity is subject to errors. There is not sufficient

reference data at this point to support using sensory studies to confirm the diagnosis of UNE.

One recent study[12]

found with 95% specificity, the sensitivities of across-elbow MNCV were

considerably better than looking at the MNCV difference between elbow and forearm segments

(80% at ADM, 77% at FDI). The sensitivity of the study may be further increased by recording

from both the FDI and ADM muscles.


In all cases, and particularly in cases with borderline NCV results, control for skin temperature

should be documented. In general, the above referenced values will hold for skin temperature in

the range of 30-34o C. Lower temperatures will be associated with falsely slowed NCV results.

ii. Needle Electromyography EMG studies are usually normal if the nerve conduction studies are entirely normal and there are

no atypical or unexplained signs or symptoms. Isolated needle EMG findings in the setting of

normal nerve conduction studies are typically not seen in UNE and could be indicative of

another diagnosis. Needle EMG study is not considered sufficient to establish a diagnosis of

ulnar neuropathy in the absence of nerve conduction changes. If performed, the most helpful

needle EMG findings in ulnar neuropathy is abnormal rest activity in the form of fibrillation

potentials and positive sharp waves in ulnar-innervated muscles in the hand and forearm, which

could suggest ongoing axonal injury. However, if there are clinical findings suggesting a

diagnosis other than or in addition to UNE, needle EMG may be appropriate, for example, to

evaluate:

a. Possible median neuropathy, demonstrated by clinical weakness or atrophy of the

thenar muscles, or abnormal median nerve conduction study.

b. Possible peripheral polyneuropathy, such as from diabetes.

c. Possible traumatic nerve injury following acute trauma to the distal upper

extremity.

d. Possible radiculopathy, with neck stiffness and radiating pain. C. OTHER DIAGNOSTIC TESTS Some studies have demonstrated that Magnetic Resonance Imaging (MRI) neurography and

ultrasound have promise in the diagnosis of UNE. However, these services will not be

authorized for this condition because the clinical utility of these tests has not yet been proven.

While the Committee recognizes that these tests may be useful in unusual circumstances where

NCV results are normal but there are appropriate clinical symptoms, the Committee believes that

at this time the use of these tests is investigational and should be used only in a research setting.

V. TREATMENT Non-surgical therapy may be considered in cases in which a provisional diagnosis has been made

(i.e. it has not been confirmed by EDS testing). Surgical treatment should be provided only in

cases where the diagnosis of UNE has been confirmed by abnormal EDS, as the potential

benefits of UNE surgery outweigh the risks of surgery only when the diagnosis of UNE has been

confirmed by abnormal EDS. A. CONSERVATIVE TREATMENT Conservative treatment is reasonable for patients presenting with early or mild symptoms, e.g.

intermittent dysesthesias, minimal motor findings, and normal EDS. The goals of conservative

treatment are to reduce the frequency and severity of symptoms and to prevent further

progression of the condition[3, 13]

.


Management should include modification of activities that exacerbate symptoms, night-time

splinting, or padding the elbow to prevent direct compression. Splinting has been reported to

provide improvement within one month for some patients[14, 15]

. However, there is no consensus

on the duration of conservative treatment and the recommended length of time varies between

one month and one year. Patients do not usually need time off from work activities prior to

surgery unless they present with objective weakness in the distribution of the ulnar nerve that

compromises workplace safety or limits work activities.

B. SURGICAL TREATMENT

Surgical treatment should be considered if:

1. The condition does not improve despite conservative treatment, and

2. The condition interferes with work or activities of daily living, and

3. The patient has met the diagnostic criteria under Section III.

Unless the patient meets criterion #3, surgery is not indicated and will not be authorized.

Surgery should include exploration of the ulnar nerve throughout its course around the elbow,

and release of all compressive structures. Complete release may require nerve decompression at

multiple sites and may also require Z-lengthening of the flexor pronator origin.

VI. RETURN TO WORK (RTW)

A. EARLY ASSESSMENT

Timeliness of the diagnosis can be a critical factor influencing RTW. Among workers with upper

extremity disorders, 7% of workers account for 75% of the long-term disability.[16]

A large

prospective study in the Washington State workers’ compensation system identified several

important predictors of long-term disability: low expectations of return to work (RTW), no offer

of a job accommodation, and high physical demands on the job.[17]

Identifying and attending to

these risk factors when patients have not returned to work within 2-3 weeks of the initial clinical

presentation may improve their chances of RTW.

Washington State workers diagnosed accurately and early were far more likely to RTW than

workers whose conditions were diagnosed weeks or months later. Early coordination of care with

improved timeliness and effective communication with the workplace is also likely to help

prevent long-term disability. A recent quality improvement project in Washington State (COHE)

has demonstrated that organized delivery of occupational health best practices similar to those

listed in Table 2 can substantially prevent long-term disability.

See next page for Table 2


Table 2. Occupational Health Quality Indicators for Ulnar Neuropathy at the Elbow (UNE)

Clinical care action Time-frame*

1. Identify physical stressors from both work

and non-work activities;

2. Screen for presence of UNE

3. Determine work-relatedness

4. Recommend ergonomic improvements

1st health care visit

Communicate with employer regarding RTW

using

1. Activity Prescription Form (or comparable

RTW form)

and/or

2. Phone call to employer

Each visit while work restrictions exist

1. Assess impediments for RTW

2. Request specialist consultation

If > 2 weeks of time-loss occurs or if there is

no clinical improvement within 6 weeks

Specialist consultation Performed ASAP, within 3 weeks of request

Electrodiagnostic studies If the diagnosis of UNE is being considered,

schedule studies immediately.

These tests are required if time-loss extends

beyond 2 weeks, or if surgery is requested.

Surgical decompression Performed ASAP, within 4-6 weeks of

determining need for surgery

*“Time-frame” is anchored in time from 1st provider visit related to UNE complaints.

B. RETURNING TO WORK FOLLOWING SURGERY

How soon a patient can return to work depends on the type of surgery performed and when

rehabilitation begins. Most patients requiring a UNE release alone can return to light duty work

within 3 weeks. Recommendations for rehabilitation vary.


VII. ELECTRODIAGNOSTIC WORKSHEET

PURPOSE AND INSTRUCTIONS

The purpose of this worksheet is to help the department’s medical and nursing staff interpret

electrodiagnostic studies (EDS) that are done for L&I patients. The worksheet should be used

only when the main purpose of the study is to evaluate a patient for UNE. It should accompany

but not replace the detailed report normally submitted to the department. We encourage you to

use the electrodiagnostic worksheet below to report EDS results, but the department will accept

the results on a report generated by your office system.

Worksheet for Ulnar Neuropathy at the Elbow Electrodiagnostic Testing

A positive UNE diagnosis can be made if at least two of the

following criteria are met:

Abnormal 1. Slowing of above elbow (AE) to below elbow (BE) nerve conduction velocity to less than 50 m/s in either ADM or FDI.

2. Focal slowing on inching studies of the ulnar nerve across the elbow, defined as a latency difference exceeding 0.7 msec across a 2-cm segment (or 0.4 msec across a 1-cm segment)

3. Compound muscle action potential (CMAP) amplitude decrease of >20% between AE and BE waveforms*

4. CMAP duration increase of >30% between AE and BE waveforms*

*For electromyographers: for findings 3 and 4, and particularly when there is an amplitude drop

between wrist and BE, the presence of Martin-Gruber anastamosis must be excluded as a cause

of these findings.

Claim Number:

Claimant Name:

Additional Comments:

Signed Date


References

1. Lund, A.T. and P.C. Amadio, Treatment of cubital tunnel syndrome: perspectives

for the therapist. Journal of Hand Therapy, 2006. 19: p. 170-179.

2. Husain, S.N. and R.A. Kaufmann, The diagnosis and treatment of cubital tunnel

syndrome. Current Orthopaedic Practice, 2008. 19(5): p. 470-474.

3. Szabo, R.M. and C. Kwak, Natural history and conservative management of

cubital tunnel syndrome. Hand Clin, 2007. 23: p. 311-318.

4. Nayan, M.E., Predictors of outcome in surgically and nonsurgically treated work-

related ulnar neuropathy at the elbow. 2003.

5. Descatha, A., et al., Incidence of ulnar nerve entrapment at the elbow in repetitive

work. Scand J Work Environ Health, 2004. 30(3): p. 234-40.

6. Piligian, G., et al., Evaluation and management of chronic work-related

musculoskeletal disorders of the distal upper extremity. Am J Ind Med, 2000. 37:

p. 75-93.

7. Mondelli, M., et al., Carpal tunnel syndrome and ulnar neuropathy at the elbow

in floor cleaners. Neurophysiologie Clinique, 2006. 36: p. 245-253.

8. Novak, C.B., et al., Provocative testing for cubital tunnel syndrome. J Hand Surg,

1994. 19A: p. 817-820.

9. Landau, M.E., K.C. Barner, and W.W. Campbell, Optimal screening distance for

ulnar neuropathy at the elbow. Muscle Nerve, 2003. 27(5): p. 570-4.

10. Landau, M.E., et al., Optimal distance for segmental nerve conduction studies

revisited. Muscle Nerve, 2003. 27(3): p. 367-9.

11. Campbell, W.W., Guidelines in electrodiagnostic medicine. Practice parameter

for electrodiagnostic studies in ulnar neuropathy at the elbow. Muscle Nerve

Suppl, 1999. 8: p. S171-205.

12. Shakir, A., P.J. Micklesen, and L.R. Robinson, Which motor nerve conduction

study is best in ulnar neuropathy at the elbow? Muscle Nerve, 2004. 29(4): p.

585-90.

13. Smith, T., K.D. Nielsen, and L. Poulsgaard, Ulnar neuropathy at the elbow:

clinical and electrophysiological outcome of surgical and conservative treatment.

Scand J Plast Reconstr Surg Hand Surg, 2000. 34(2): p. 145-8.

14. Dellon, A.L., W. Hament, and A. Gittelshon, Nonoperative management of

cubital tunnel syndrome: an 8-year prospective study. Neurology, 1993. 43: p.

1673-1677.

15. Hong, C., et al., Splinting and local steroid injection for the treatment of ulnar

neuropathy at the elbow: clinical and electrophysiological examination. Arch

Phys Med Rehabil, 1996. 77: p. 573-577.

16. Hashemi, L., et al., Length of disability and cost of work-related musculoskeletal

disorders of the upper extremity. J Occup Environ Med 1998. 40: p. 261-269.

17. Turner, J.A., G. Franklin, and D. Fulton-Kehoe, Early predictors of chronic work

disability associated with carpal tunnel syndrome: a longitudinal workers’

compensation cohort study. Am J Ind Med 2007. 50: p. 489-500.


Acknowledgements

Acknowledgement and gratitude go to all subcommittee members, clinical experts, and

consultants who contributed to this important guideline:

IIMAC Committee Members

Gregory T. Carter MD MS

Dianna Chamblin MD – Chair

G.A. DeAndrea MD MBA

Jordan Firestone, MD PhD MPH

Andrew Friedman MD

Subcommittee Clinical Experts

Christopher H. Allan MD

Lawrence R. Robinson MD

Thomas E. Trumble MD

Nicholas B. Vedder MD

Michael D. Weiss MD

Consultants:

Terrell Kjerulf MD

Ken O’Bara MD

Department staff who helped develop and prepare this guideline include:

Gary M. Franklin MD, MPH, Medical Director

Lee Glass MD, JD, Associate Medical Director

Simone P. Javaher BSN, MPA, Occupational Nurse Consultant

Reshma N. Kearney MPH, Epidemiologist

Bintu Marong MS, Epidemiologist

Medical Treatment Guidelines Washington State Department of Labor and Industries

Effective Date April 1, 2010 Page 1

Work-Related Radial Nerve Entrapment:

Diagnosis and Treatment*

Table of Contents

I. Introduction

II. Establishing Work-Relatedness

III. Making the Diagnosis




IV. Treatment



V. Return to Work (RTW)

A. Early Assessment

B. Returning to Work following Surgery

VI. Electrodiagnostic Worksheet

VII. Guideline Summary

*This guideline does not apply to severe or acute traumatic injury to the upper extremities.


Work-Related Radial Nerve Entrapment:

Diagnosis and Treatment The medical treatment guidelines are written from a clinical perspective, to guide clinical care. Providers

should consult the Medical Aid Rules and Fee Schedule (MARFS) for documentation and coding

requirements.

I. INTRODUCTION This guideline is to be used by physicians, Labor and Industries claim managers, occupational nurses, and utilization review staff. The emphasis is on accurate diagnosis and treatment that is curative or rehabilitative (see WAC 296-20-01002 for definitions). An electrodiagnostic worksheet and guideline summary are appended to the end of this document.

This guideline was developed in 2010 by the Washington State Industrial Insurance Medical Advisory

Committee (IIMAC) and its subcommittee on Upper Extremity Entrapment Neuropathies. The

subcommittee presented its work to the full IIMAC, and the IIMAC made an advisory recommendation to

the Washington State Department of Labor & Industries to adopt the guideline. This guideline was based

on the weight of the best available clinical and scientific evidence from a systematic review of the

literature* and a consensus of expert opinion. One of the Committee's primary goals is to provide

standards that ensure a uniformly high quality of care for injured workers in Washington State. Radial nerve entrapment (RNE) is uncommon in the absence of acute trauma. When it occurs in relation to work, RNE usually refers to one of two syndromes: radial tunnel syndrome (RTS) or posterior interosseous nerve syndrome (PINS)

1,2. Although RNE may occur from compression at any point along

the course of the radial nerve due to acute trauma (e.g. humerus fracture, Saturday night palsy), space-occupying lesion (e.g. lipoma, ganglion), local edema or inflammation, this guideline focuses on RTS and PINS, which are more typical for RNE arising from repetitive work activities. RTS and PINS have been described to occur at one of five potential sites. These sites, from proximal to distal, include the fibrous bands of the radiocapitellar joint, radial recurrent vessels (the leash of Henry), the tendinous edge of the extensor carpi radialis brevis, the arcade of Frohse, and the distal edge of the supinator. Most cases of RNE have been described at the arcade of Frohse. In general, work-relatedness and appropriate symptoms and objective signs must be present for Labor and Industries to accept RNE on a claim. Electrodiagnostic studies (EDS), including nerve conduction velocity studies (NCVs) and needle electromyography (EMG), should be scheduled immediately to confirm the clinical diagnosis. If time loss extends beyond two weeks or if surgery is requested, completion of EDS is required and does not need prior authorization. II. ESTABLISHING WORK-RELATEDNESS Work related activities may cause or contribute to the development of RNE. Establishing work-

relatedness requires all of the following:

1. Exposure: Workplace activities that contribute to or cause RNE, and 2. Outcome: A diagnosis of RNE that meets the diagnostic criteria under Section III, and 3. Relationship: Generally accepted scientific evidence, which establishes on a more probable than

not basis (greater than 50%) that the workplace activities (exposure) in an individual case contributed to the development or worsening of the condition (outcome).

* Evidence was classified using criteria defined by the American Academy of Neurology (see references)


When the Department receives notification of an occupational disease, the Occupational Disease &

Employment History form is mailed to the worker, employer or attending provider. The form should be

completed and returned to the insurer as soon as possible. If the worker’s attending provider completes

the form, provides a detailed history in the chart note, and gives an opinion on causality, he or she may be

paid for this (use billing code 1055M). Additional billing information is available in the Attending

Doctor’s Handbook. Certain work-related activities have been associated with RNE, usually those requiring forceful and

repetitive elbow extension and forearm supination, handling of loads greater than 1 kg, and firm pinching

or squeezing of objects or hand tools3,4

. Jobs where these activities often occur may include but are not

limited to the following 3,5-8

: Construction Smelting Machine tuning Assembly line inspection Sewing Packing Several occupations have been described in association with RNE. This is not an exhaustive list and is meant only as a guide in the consideration of work-relatedness

5-9:

Truck driver Cement or brick layer Assembly line worker Automobile brakes industry worker Television industry worker Shoes and clothing industry worker Mechanic Ice cream packer Seamstress Secretary

III. MAKING THE DIAGNOSIS A. SYMPTOMS AND SIGNS

A case definition of confirmed RNE includes appropriate symptoms, objective physical findings

("signs"), and abnormal electrodiagnostic studies. A provisional diagnosis of RNE may be made based

upon appropriate symptoms and objective signs, but confirmation of the diagnosis requires abnormal

EDS.

Symptoms associated with RNE may include weakness in radial innervated muscles and pain or aching over the proximal, lateral forearm. Patients may report an increase in pain severity with an increase in activity or during sleep. Loss of motor function is most common with PINS

10.

Signs on examination may include tenderness over the radial nerve distal to the lateral epicondyle. Tenderness on palpation is a useful objective finding, but cannot support the diagnosis of RNE alone. Motor findings include difficulty extending the thumb, fingers, or wrist

11. Motor testing should compare

strength of radial innervated muscles to strength of the same muscles in the non-affected limb as well as non-radial innervated muscles of the affected limb (see Table 1). Atrophy of affected muscles may be seen in chronic or severe cases. Provocative tests have been described to help corroborate the diagnosis of RNE. These include pressure over the radial tunnel (“radial nerve compression test”), resisted supination with the elbow extended (“resisted supination test”), and resisted extension of the middle-finger at the metacarpophalangeal joint (“middle-finger test”). These tests are based on creating maximal tension on the anatomical sites that are


involved in RNE 12

. However, sensitivity and specificity of these tests have not been established and these tests can not replace the objective signs discussed below.

Table 1. Muscles Innervated by the Radial Nerve

In the arm, via the muscular branch of the radial nerve

triceps brachii (long head, medial head, lateral head)

anconeous

brachioradialis

extensor carpi radialis longus

In the forearm, via the deep branch of the radial nerve

extensor carpi radialis brevis

supinator

In the forearm, via the posterior interosseous nerve:

extensor digitorum communis

extensor digiti minimi

extensor carpi ulnaris

abductor pollicis longus

extensor pollicis brevis

extensor pollicis longus

extensor indicis proprius

Every effort should be made to objectively confirm the diagnosis of RNE before considering surgery. A

differential diagnosis for RNE includes extensor tendinitis and lateral epicondylitis (which can coexist

with RNE), neuralgic amyotrophy, brachial plexopathy, or cervical radiculopathy 5,13

14

.

B. ELECTRODIAGNOSTIC STUDIES (EDS) Electromyographic (EMG) abnormalities are required to objectively confirm the diagnosis of RNE. NCV abnormalities, such as radial motor or sensory conduction block across the elbow, or reduced sensory nerve action potentials, are of unproven utility, so NCV alone should not be relied upon to confirm the diagnosis. EDS confirmation requires abnormal EMG, with evidence of denervation in muscles supplied by the posterior interosseous nerve with or without denervation in other radial-innervated forearm muscles. EDS should exclude other potential causes of neuropathic symptoms, such as cervical radiculopathy, brachial plexopathy, or neuralgic amyotrophy. A worksheet to help interpret EDS results is provided in Section VI. C. OTHER DIAGNOSTIC TESTS It has been suggested that Magnetic Resonance Imaging (MRI) neurography may be helpful in the diagnosis of RNE

15. However, these services will not be authorized for this condition because their

clinical utility has not yet been proven. While the Committee recognizes that MRI neurography may be useful in unusual circumstances where EDS results are normal in a patient with appropriate clinical symptoms, the Committee believes that at this time MRI for this purpose is investigational and should be used only in a research setting.

IV. TREATMENT


No randomized controlled trials or controlled clinical trials have measured the effectiveness of any

treatment interventions16

. Non-surgical therapy may be considered for cases in which a provisional

diagnosis has been made. Surgical treatment should be provided only for cases in which the diagnosis of

RNE has been confirmed by abnormal EDS. Under these circumstances, the potential benefits of radial

nerve decompression may outweigh the risks of surgery.

A. CONSERVATIVE TREATMENT

Conservative treatment for RNE has been described in narrative reviews, case reports, and retrospective

case series. Examples include modification of activities that exacerbate symptoms, splinting to maintain

forearm supination and/or wrist extension, physical therapy, and anti-inflammatory drug therapy 6,8,10,17,18

.

No specific method of conservative treatment has been proven to be most effective.

When feasible, job modifications that reduce the intensity of manual tasks may prevent progression and

promote recovery from RNE. If symptoms persist despite appropriate treatment, permanent job

modifications may still allow the patient to remain at work.

Patients do not usually need time off from work activities prior to surgery, unless they present with

objective weakness or sensory loss in the distribution of the radial nerve that limits work activities or

poses a substantial safety risk. B. SURGICAL TREATMENT

Surgical treatment for RNE has been described in narrative reviews, case reports, and retrospective case

series 6,9,17,19,20

. Surgery should include exploration of the radial nerve throughout its course in order to

decompress it by resecting any compressive and/or constrictive structures. These may include any of the

five sites of compression mentioned earlier. No specific method of surgical treatment has been proven to

be most effective.

Surgical treatment should only be considered if:

1. The patient has met the diagnostic criteria under Section III, and

2. The condition interferes with work or activities of daily living, and

3. The condition does not improve despite conservative treatment

Without confirmation of radial nerve entrapment by both objective clinical findings and abnormal

EDS, surgery will not be authorized. V. RETURN TO WORK (RTW)

A. EARLY ASSESSMENT

Timeliness of the diagnosis can be a critical factor influencing RTW. Among workers with upper

extremity disorders, 7% of workers account for 75% of the long-term disability.21

A large prospective

study in the Washington State workers’ compensation system identified several important predictors of

long-term disability: low expectations of return to work (RTW), no offer of a job accommodation, and

high physical demands on the job.22

Identifying and attending to these risk factors when patients have not

returned to work within 2-3 weeks of the initial clinical presentation may improve their chances of RTW.

Washington State workers diagnosed accurately and early were far more likely to RTW than workers

whose conditions were diagnosed weeks or months later. Early coordination of care with improved


timeliness and effective communication with the workplace is also likely to help prevent long-term

disability.

A recent quality improvement project in Washington State has demonstrated that delivering medical care

according to occupational health best practices similar to those listed in Table 1 can substantially prevent

long-term disability. Findings can be viewed at:

http://www.lni.wa.gov/ClaimsIns/Files/Providers/ohs/CoheSummaryFindings1207.pdf .

Table 2. Occupational Health Quality Indicators for Work-Related Radial Nerve Entrapment

(RNE)


1. Identify physical stressors from both work and non-

work activities;

2. Screen for presence of RNE




Communicate with employer regarding return to work

(RTW) using

1. Activity Prescription Form (or comparable RTW

form)

and/or





If > 2 weeks of time-loss occurs or if there is no clinical

improvement within 6 weeks


Electrodiagnostic studies If the diagnosis of RNE is being considered, schedule

studies immediately.

These tests are required if time-loss extends beyond 2

weeks, or if surgery is requested.

Surgical decompression Performed ASAP, within 4-6 weeks of determining need

for surgery

*“Time-frame” is anchored in time from 1st provider visit related to RNE complaints.



How soon a patient can return to work depends on the type of surgery performed and when rehabilitation

begins. Most patients can return to light duty work within 3 weeks and regular duty within 6 weeks of

surgery. Hand therapy may help patients regain their range of motion and strength.

VI. ELECTRODIAGNOSTIC WORKSHEET

Claim Number:

Claimant Name:


The purpose of this worksheet is to help medical and nursing staff interpret electrodiagnostic studies

(EDS) done for an injured worker. The worksheet should be used only when the main purpose of the

study is to evaluate radial nerve entrapment (RNE). It should accompany but not replace the detailed

report normally submitted to the insurer. We encourage you to use the electrodiagnostic worksheet below

to report electromyography (EMG) results, but we will accept the results on a report generated by your

office system.

Electrodiagnostic Worksheet for Work-Related Radial Nerve Entrapment (RNE)

Electromyography criteria that confirm the diagnosis of Work-Related RNE (radial

tunnel syndrome OR posterior interosseous nerve syndrome) include the following:

Abnormal

muscles 1. Abnormal needle EMG with evidence of denervation (e.g. increased insertional activity,

fibrillation potentials, positive sharp waves) in at least one muscle supplied by the posterior

interosseous nerve (extensor digitorum minimi, extensor carpi ulnaris, abductor pollicus

longus, extensor pollicus brevis, extensor pollicus longus, extensor indicis proprius) and/or

radial innervated muscles distal to the brachioradialis including the extensor carpi radialis

brevis and supinator (excluding the extensor carpi radialis longus due to its variable take

off).

AND 2. Normal needle EMG of at least one muscle supplied by radial nerve branches above the

elbow (triceps, anconeus, brachioradialis). If abnormal, consider alternative explanations

for radial nerve injury above the elbow.

AND 3. Normal needle EMG of at least one muscle supplied by the ulnar or median nerve that

includes C7 innervation. If abnormal, consider cervical nerve root compression or lower

brachial plexopathy.



Signed Date

Effectiv

e Date A

pril 1

, 20

10

Page 9

V

II. GU

IDE

LIN

E S

UM

MA

RY

*W

ork

-Related

Rad

ial Nerv

e Entrap

men

t: radial tu

nnel sy

ndro

me (R

TS

) or p

osterio

r intero

sseous n

erve sy

ndro

me (P

INS

)

Rev

iew C

riteria fo

r the D

iag

no

sis an

d T

reatm

ent o

f

Wo

rk-R

elated

Ra

dia

l Nerv

e En

trap

men

t (RN

E*

) C

LIN

ICA

L F

IND

ING

S

CO

NS

ER

VA

TIV

E

TR

EA

TM

EN

T

SU

RG

ICA

L

TR

EA

TM

EN

T

SU

BJ

EC

TIV

E

(Sy

mp

tom

s)

OB

JE

CT

IVE

(Sig

ns)

DIA

GN

OS

TIC

AN

D A

ND

Weak

ness o

f wrist o

r finger

exten

sion

OR

Pain

/ache o

ver th

e

pro

xim

al, lateral forearm

Weak

ness in

radial in

nerv

ated

mu

scles

OR

Pressu

re over th

e radial n

erve

pro

vo

kes p

ain/ te

nd

erness

Need

le electrom

yo

grap

hy (E

MG

)

sho

win

g R

TS

or P

INS

by:

Evid

ence o

f den

ervatio

n in

muscle

s

sup

plied

by th

e po

sterior in

terosseo

us

nerv

e (PIN

) or rad

ial nerv

e distal to

the

brach

iorad

ialis

AN

D

No

rmal fin

din

gs in

mu

scles in

nerv

ated

by th

e radial n

erve p

roxim

al to th

e

radial tu

nnel an

d P

IN (b

rachio

radialis,

anco

niu

s and

triceps m

uscle

s)

AN

D

Exclu

sion o

f oth

er po

tential ca

use

s of

neu

rop

athic sy

mp

tom

s, such

as

neu

ralgic a

myo

trop

hy, b

rachia

l

plex

op

athy, o

r cervical rad

iculo

path

y

Mo

dificatio

n o

f activities th

at

exacerb

ate sym

pto

ms

AN

D

Sp

lintin

g to

main

tain fo

rearm

sup

inatio

n a

nd

/or w

rist exte

nsio

n

AN

D/O

R

Ph

ysical th

erapy

AN

D/O

R

Anti-in

flam

mato

ry d

rug th

erap

y

Surg

ical treatment sh

ould

only

be

consid

ered if:

1. T

he p

atient h

as met th

e

diag

no

stic criteria und

er Sectio

n

III

AN

D

2. T

he co

nd

ition in

terferes with

wo

rk o

r activities o

f daily

livin

g

AN

D

3. T

he co

nd

ition d

oes n

ot

imp

rove d

espite co

nserv

ative

treatment

With

out co

nfirm

ation o

f nerv

e

entrap

ment b

y b

oth

ob

jectiv

e

clinica

l find

ing

s an

d a

bn

orm

al

ED

S, su

rgery

will n

ot b

e

auth

orized

.


References Evidence was classified using criteria defined by the American Academy of Neurology†

1. Kim DH, Murovic JA, Kim YY, Kline DG. Surgical treatment and outcomes in

45 cases of posterior interosseous nerve entrapments and injuries. J Neurosurg

2006;104(5):766-77. IV

2. Plate AM, Green SM. Compressive radial neuropathies. Instr Course Lect

2000;49:295-304. Review

3. Roquelaure Y, Raimbeau G, Dano C, Martin YH, Pelier-Cady MC, Mechali S,

Benetti F, Mariel J, Fanello S, Penneau-Fontbonne D. Occupational risk factors

for radial tunnel syndrome in industrial workers. Scand J Work Environ Health

2000;26(6):507-13. III

4. van Rijn RM, Huisstede BM, Koes BW, Burdorf A. Associations between work-

related factors and specific disorders at the elbow: a systematic literature review.

Rheumatology (Oxford) 2009;48(5):528-36. Systematic Review

5. Fardin P, Negrin P, Sparta S, Zuliani C, Cacciavillani M, Colledan L. Posterior

interosseous nerve neuropathy: clinical and electromyographical aspects.

Electromyogr Clin Neurophysiol 1992;32:229-234. IV

6. Jebson PJ, Engber WD. Radial tunnel syndrome: long-term results of surgical

decompression. J Hand Surg Am 1997;22(5):889-96. IV

7. Kupfer DM, Bronson J, Lee GW, Beck J, Gillet J. Differential latency testing: a

more sensitive test for radial tunnel syndrome. J Hand Surg Am 1998;23(5):859-

64. IV

8. Lee JT, Azari K, Jones NF. Long term results of radial tunnel release--the effect

of co-existing tennis elbow, multiple compression syndromes and workers'

compensation. J Plast Reconstr Aesthet Surg 2008;61(9):1095-9. IV

9. Verhaar J, Spaans F. Radial tunnel syndrome. An investigation of compression

neuropathy as a possible cause. J Bone Joint Surg Am 1991;73(4):539-44. IV

10. Bolster MA, Bakker XR. Radial tunnel syndrome: emphasis on the superficial

branch of the radial nerve. J Hand Surg Eur Vol 2009;34(3):343-7. IV

11. Cravens G, Kline DG. Posterior interosseous nerve palsies. Neurosurgery

1990;27(3):397-402. IV

12. Lubahn JD, Cermak MB. Uncommon nerve compression syndromes of the upper

extremity. J Am Acad Orthop Surg 1998;6(6):378-86. Review

13. Sarris IK, Papadimitriou NG, Sotereanos DG. Radial tunnel syndrome. Tech

Hand Up Extrem Surg 2002;6(4):209-12. Review

14. Mondelli M, Morano P, Ballerini M, Rossi S, Giannini F. Mononeuropathies of

the radial nerve: clinical and neurographic findings in 91 consecutive cases.

Journal of Electromyography and Kinesiology 2005;15:377-383. IV

15. Ferdinand BD, Rosenberg ZS, Schweitzer ME, Stuchin SA, Jazrawi LM, Lenzo

SR, Meislin RJ, Kiprovski K. MR imaging features of radial tunnel syndrome:

initial experience. Radiology 2006;240(1):161-8. IV

† Edlund W, Gronseth G, So Y, Franklin G. Clinical Practice Guideline Process Manual. American Academy of

Neurology 2004 . (www.aan.com).


16. Huisstede B, Miedema HS, van Opstal T, de Ronde MT, Verhaar JA, Koes BW.

Interventions for treating the radial tunnel syndrome: a systematic review of

observational studies. J Hand Surg Am 2008;33(1):72-8. Systematic Review

17. Atroshi I, Johnsson R, Ornstein E. Radial tunnel release. Unpredictable outcome

in 37 consecutive cases with a 1-5 year follow-up. Acta Orthop Scand

1995;66(3):255-7. IV

18. Sotereanos DG, Varitimidis SE, Giannakopoulos PN, Westkaemper JG. Results

of surgical treatment for radial tunnel syndrome. J Hand Surg Am

1999;24(3):566-70. IV

19. De Smet L, Van Raebroeckx T, Van Ransbeeck H. Radial tunnel release and

tennis elbow: disappointing results? Acta Orthop Belg 1999;65(4):510-3. IV

20. Rinker B, Effron CR, Beasley RW. Proximal radial compression neuropathy. Ann

Plast Surg 2004;52(2):174-80; discussion 181-3. IV

21. Hashemi L, Webster BS, Clance EA, Courtney TK. Length of disability and cost

of work-related musculoskeletal disorders of the upper extremity. J Occup

Environ Med 1998;40:261-269. Descriptive Study

22. Turner JA, Franklin G, Fulton-Kehoe D. Early predictors of chronic work

disability associated with carpal tunnel syndrome: a longitudinal workers’

compensation cohort study. Am J Ind Med 2007;50:489-500. II

Medical Treatment Guidelines Washington State Department of Labor and Industries

Effective Date August 1, 2009, updated August 2014 1

Work-Related Proximal Median Nerve Entrapment (PMNE)


Table of Contents

I. Review Criteria

II. Introduction

III. Establishing Work-Relatedness

IV. Making the Diagnosis




V. Treatment



VI. Return to Work (RTW)

A. Early Assessment

B. Returning to Work Following Surgery

VII. Electrodiagnostic Worksheet

Med

ical T

reatm

ent G

uid

elines

Wa

shin

gto

n S

tate D

ep

artm

ent o

f La

bor a

nd

Ind

ustries

I. RE

VIE

W C

RIT

ER

IA F

OR

SU

RG

ER

Y

Effectiv

e Date A

ugu

st 1, 2

00

9, u

pd

ated A

ugu

st 20

14

2

As req

uest

may

be

app

ropriate

for

If the

patien

t has

AN

D th

e diag

no

sis is sup

po

rted b

y th

ese clinical fin

din

gs

AN

D th

is has b

een

do

ne (if

recom

men

ded

)

Su

rgical

Pro

cedu

re

Diag

no

sis S

ub

jective

Ob

jective

Diag

no

stic tests

Pro

xim

al

Med

ian N

erve

En

trapm

ent

Release

Pro

xim

al

Med

ian

Nerv

e

En

trapm

ent

(PM

NE

)

Pain

in th

e

pro

xim

al vo

lar area

of th

e forearm

(pain

may

be ex

acerbated

with

increased

ph

ysical activ

ity).

OR

Paresth

esias in th

e

first 3 d

igits

(med

ian

distrib

utio

n) o

f the

affected arm

.

Ten

dern

ess to p

alpatio

n

ov

er pro

nato

r teres mu

scle.

OR

Weak

ness o

f deep

flexo

r

mu

scles sup

plied

by th

e

pro

xim

al med

ian n

erve

[pro

nato

r teres, flexo

r carpi

radialis, flex

or d

igito

rum

sup

erficialis, flexo

r

dig

itoru

m p

rofu

nd

us (rad

ial

half), flex

or p

ollicis lo

ng

us,

pro

nato

r qu

adratu

s] as well

as the m

uscles su

pp

lied b

y

the d

istal med

ian n

erve

(abd

ucto

r pollicis b

revis,

flexo

r po

llicis brev

is,

op

po

nen

s po

llicis).

Electro

diag

no

stic stud

ies

(ED

S), i.e, n

erve co

nd

uctio

n

velo

city (N

CV

) and

electrom

yo

grap

hy (E

MG

)

are requ

ired to

ob

jectively

con

firm th

e diag

no

sis of

PM

NE

.

ED

S are u

seful b

oth

to

diag

no

se PM

NE

and

to ru

le

ou

t oth

er po

tential sites o

f

med

ian n

erve co

mp

ression

,

such

as carpal tu

nn

el

syn

dro

me (C

TS

).

Po

sitive E

MG

criteria are as

follo

ws:

1. E

vid

ence o

f den

ervatio

n in

a mu

scle sup

po

rted b

y th

e

anterio

r intero

sseou

s nerv

e

(flexo

r po

llicis lon

gu

s,

Co

nserv

ative care

requ

ired fo

r at

least 6 w

eeks.

Co

nserv

ative care

sho

uld

inclu

de:

rest, mo

dified

activities, sp

lintin

g

at wrist an

d elb

ow

,

ph

ysical th

erapy,

anti-in

flamm

atory

dru

g th

erapy,

cortico

steroid

injectio

ns if

ind

icated.

3

pro

nato

r qu

adratu

s, or rad

ial

aspect o

f the flex

or

dig

itoru

m p

rofu

nd

us).

OR

2. E

vid

ence o

f den

ervatio

n in

a med

ian in

nerv

ated m

uscle

in th

e forearm

(pro

nato

r

teres, flexo

r carpi rad

ialis,

flexo

r dig

itoru

m

sup

erficialis).

AN

D

3. E

vid

ence o

f den

ervatio

n in

a med

ian in

nerv

ated m

uscle

in th

e han

d (ab

du

ctor p

ollicis

brev

is, flexo

r po

llicis brev

is,

op

po

nen

s po

licis).

AN

D

4. N

eedle E

MG

of at least

on

e mu

scle sup

plied

by th

e

uln

ar or rad

ial nerv

e sho

uld

be n

orm

al

A p

ure A

nterio

r Intero

sseou

s

Syn

dro

me (A

IN) w

ou

ld o

nly

need

to m

eet criteria 1 an

d 4

.


Work-Related Proximal Median Nerve Entrapment (PMNE)


II. INTRODUCTION

This guideline is to be used by physicians, claim managers, and utilization review staff. The

emphasis is on accurate diagnosis and treatment that is curative or rehabilitative (see WAC 296-

20-01002 for definitions). An electrodiagnostic worksheet and guideline summary are appended

to the end of this document.

This guideline was developed in 2009, and reviewed and updated in 2014, by Washington State's

Labor and Industries’ Industrial Insurance Medical Advisory Committee (IIMAC) and its

subcommittee on Upper Extremity Entrapment Neuropathies. It focuses on work-related medical

conditions. One of the subcommittee's goals is to provide standards that ensure a uniformly high

quality of care for injured workers in Washington State. The IIMAC unanimously approved this

guideline.

The subcommittee is comprised of a group of physicians of various medical specialties,

including rehabilitation medicine, occupational medicine, orthopedic surgery, plastic surgery,

neurosurgery, neurology, pain medicine, and electrodiagnostic medicine. The subcommittee

based its recommendations on the weight of the best available clinical and scientific evidence

from a systematic review of the literature. PMNE is a rare entrapment neuropathy and there are

no high quality clinical or scientific studies regarding this condition. Nonetheless, the

subcommittee's consensus opinion is that objective confirmation of the PMNE diagnosis is

critical to making the correct diagnosis and directing appropriate treatment.

Compression near the antecubital fossa can occur as the nerve traverses any of the following

anatomic structures: the ligament of Struthers/supracondylar process, the lacertus fibrosis

(bicipital aponeurosis), the fascia of the pronator teres, or the fibrous arch formed by fascia of the

flexor digitorum superficialis. Entrapment of the median nerve in the proximal forearm must be

distinguished from more distal sites of entrapment such as at the wrist (carpal tunnel) or at the

anterior interosseous nerve branch (which supplies no cutaneous sensation).

In general, both work-relatedness and appropriate symptoms and signs must be present to

accept proximal median nerve entrapment on a claim. Electrodiagnostic studies (EDS),

including nerve conduction velocity studies (NCVs) and needle electromyography (EMG),

should be scheduled immediately to corroborate the clinical diagnosis. Completion of EDS

is required if time loss extends beyond two weeks or if surgery is requested.

III. ESTABLISHING WORK-RELATEDNESS

Work related activities may cause or contribute to the development of PMNE. Establishing

work-relatedness requires all of the following:


1. Exposure: Workplace activities that contribute to or cause PMNE, and

2. Outcome: A diagnosis of PMNE that meets the diagnostic criteria under Section III, and

3. Relationship: Generally accepted scientific evidence, which establishes on a more

probable than not basis (greater than 50%) that the workplace activities (exposure) in an

individual case contributed to the development or worsening of the condition (outcome).

Work-related PMNE is most often associated with activities requiring extensive, repetitive,

forceful, or prolonged use of the elbow or forearm. Usually, one or more of the following work

exposures occurs on a regular basis 1-4

: This is not an exhaustive list and is meant only as a guide in the consideration of work-

relatedness.

Heavy labor Using vibrating hand tools

Repetitive grasping Prolonged hammering

Lifting, carrying, placing heavy objects Scraping dishes

Packaging motions Ladling food

The types of jobs most mentioned in the literature or reported in L&I’s data as being associated

with PMNE are listed below5-8

:

Assembly line worker Cashier

Carpenter Cook

Mechanic Server

Woodworker Barber

Concrete worker Dentist

Shoveller Nurse

Clerk Milker

IV. MAKING THE DIAGNOSIS

A. SYMPTOMS AND SIGNS

Our case definition of confirmed PMNE includes appropriate symptoms, objective physical

findings (signs), and abnormal electrodiagnostic studies. A provisional diagnosis of PMNE may

be made based upon appropriate symptoms and objective signs, alone, but confirmation of the

diagnosis requires abnormal EDS. Non-surgical therapy may be considered in cases in which a

provisional diagnosis has been made. Surgical treatment should be provided only in cases where

the diagnosis of PMNE has been confirmed by abnormal EDS, as the potential benefits of

surgery outweigh the risks only when the diagnosis of PMNE has been confirmed by abnormal

EDS.


The primary symptom associated with PMNE is pain in the proximal volar area of the forearm.

Many patients report an increase in pain severity with an increase in activity. Other symptoms

may include weakness in the forearm and the hand (such as a decrease in grip strength),

cramping in the hand (writer’s cramp), and paresthesia or numbness in the first three digits.1, 3, 9-

12 Nocturnal symptoms are not as common for PMNE as they are for carpal tunnel syndrome

(CTS).

Physical signs include tenderness in the forearm over the pronator teres muscle and along the

median nerve distribution. Unlike median entrapment at the carpal tunnel, if weakness is

present, it should involve muscles supplied by the median nerve both above and below the wrist.

Tinel’s sign (paresthesias radiating in a median nerve distribution with pressure or tapping over

the median nerve in the forearm) may be present, but by itself is not specifically diagnostic of

PMNE. A positive Phalen’s sign (paresthesias radiating in a median nerve distribution with

sustained flexion of the wrist) or Tinel’s sign with tapping over the wrist more likely indicates

CTS rather than PMNE.

Three provocative tests have been described to help corroborate the site of compression for

PMNE. These provocative tests do not replace the objective signs discussed below. Sensitivity

and specificity of these provocative tests have not been established. The tests are based on

creating maximal tension on the anatomical sites that can contribute to PMNE:

1. The pronator teres muscle is implicated if symptoms are reproduced upon resisted

pronation of the forearm in neutral position with the elbow extended.

2. The lacertus fibrosis (bicipital aponeurosis) is implicated if symptoms are reproduced

upon resisted elbow flexion at 120-130 degrees flexion with the forearm in maximal

supination.

3. The flexor digitorum superficialis is implicated if symptoms are reproduced upon resisted

flexion of the proximal interphalangeal joint to the long finger (“middle finger flexion

test”).11-13

Every effort should be made to objectively verify the diagnosis of PMNE before considering

surgery. One potentially competing diagnosis is a non-traumatic inflammatory neuritis-

Parsonage-Turner Syndrome- which may produce dysfunction in a median nerve distribution that

can mimic PMNE. This condition often produces more widespread abnormalities affecting

multiple upper extremity nerves. Also, it is usually accompanied by proximal pain around the

shoulder girdle, rather than in the forearm. This condition usually improves spontaneously in six

to twelve months. This idiopathic condition would not normally be considered a work-related

condition.

B. ELECTRODIAGNOSTIC STUDIES (EDS)

Electrodiagnostic studies (NCVs and EMG) are required to objectively confirm the diagnosis of

PMNE. EDS are useful both to diagnose PMNE and to rule out other potential sites of median

nerve compression, such as CTS. Unlike the distal median nerve entrapment within the carpal

tunnel, NCVs in proximal median nerve entrapment are often normal.1, 2, 9

Short segment nerve

conduction studies have not been demonstrated to reliably diagnose this entity. However, EMG

studies may show an abnormality in the distribution of the proximal median nerve of the


forearm. The diagnosis is specifically confirmed by EMG demonstrating membrane instability

(e.g. increased insertional activity, fibrillation potentials, positive sharp waves) of median

innervated muscles both below and above the wrist in the forearm (unlike CTS which should

only affect median innervated muscles below the wrist).10

C. OTHER DIAGNOSTIC TESTS

The scientific evidence is insufficient to support the use of magnetic resonance neurography

(MRN) or MRI in the diagnosis of PMNE 14, 15

.

V. TREATMENT

A. CONSERVATIVE TREATMENT

Conservative treatment for PMNE has been described only in narrative reviews, case reports, and

retrospective case series. Examples include rest, modification of activities that exacerbate

symptoms, splinting at wrist and elbow, physical therapy, anti-inflammatory drug therapy, and

corticosteroid injections.2, 6, 9, 11, 12, 16

Patients do not usually need time off from work activities

prior to surgery unless they present with objective weakness or sensory loss in the distribution of

the proximal median nerve that limits work activities or poses a substantial safety risk.

B. SURGICAL TREATMENT

Without confirmation of nerve compression by both objective clinical findings and abnormal

EDS, surgery will not be authorized.

Surgical treatment for PMNE has been described only in narrative reviews, case reports, and

retrospective case series. Surgical treatment should only be considered if the condition does not

improve despite conservative treatment, or if the condition interferes with work or activities of

daily living. Surgical treatment is only indicated in patients who have appropriate symptoms and

one or more of the objective clinical findings described above in addition to abnormal EDS.

Surgery should include exploration of the median nerve throughout its proximal course and

release of all compressive structures, which may include the ligament of Struthers (if it is

present), the lacertus fibrosis (bicipital aponeurosis), the fascia of the pronator teres (PT), and the

fascia of the flexor digitorum superficialis (FDS).17, 18

Although complete release may require

nerve decompression at multiple sites, this is considered a single procedure.

In rare cases with long standing motor palsy of part or all of the median nerve, tendon transfers

may be considered to hasten return to function. When a complete palsy has been present for one

or more muscles for three or more months, the patient and the surgeon should consider the

options for tendon transfers. In patients who have already had a decompression of the proximal

median nerve six months or more previously with incomplete return of motor function, repeat

EDS are recommended. If the EDS show no improvement or worse neurologic function, a re-

exploration may be necessary.


Patients with PMNE rarely present with prominent sensory symptoms. For patients with a

preoperative loss of sensation who do not have recovery of sensation six months or more after

surgical treatment, repeat EDS are recommended. If the EDS show no improvement or worse

neurologic function, a re-exploration may be necessary.

VI. RETURN TO WORK (RTW)

A. EARLY ASSESSMENT

Among workers with upper extremity disorders, 7% of workers account for 75% of the long-

term disability.19

A large prospective study in the Washington State workers’ compensation

system identified several important predictors of long-term disability: low expectations of return

to work (RTW), no offer of a job accommodation, and high physical demands on the job.20

Identifying and attending to these risk factors when patients have not returned to work within 2-3

weeks of the initial clinical presentation may improve their chances of RTW.

Timeliness of the diagnosis can be a critical factor influencing RTW. Washington State workers

diagnosed accurately and early were far more likely to RTW than workers whose condition was

diagnosed weeks or months later. Early coordination of care with improved timeliness and

effective communication with the workplace is also likely to help prevent long-term disability.

A Washington State quality improvement project has demonstrated that organized delivery of

occupational health best practices similar to those in Table 1 can substantially prevent long-term

disability 21

. See also the Centers of Occupational Health and Education:

http://www.lni.wa.gov/ClaimsIns/Providers/ProjResearchComm/OHS/default.asp

Requirements for filing a claim for an occupational disease can be found in the Attending

Provider’s Handbook: http://www.lni.wa.gov/FormPub/Detail.asp?DocID=1669.

See next page for Table 1


Table 1. Occupational Health Quality Indicators for Proximal Median Nerve Entrapment


1. Identify physical stressors from both work

and non-work activities;

2. Screen for presence of PMNE




Communicate with employer regarding RTW

using

1. Activity Prescription Form

(or comparable RTW form)

and/or





If > 2 weeks of time-loss occurs or if there is

no clinical improvement within 6 weeks


Electrodiagnostic studies If the diagnosis of PMNE is being considered,

schedule studies immediately.

These tests are required if time-loss extends

beyond 2 weeks, or if surgery is requested.

Surgical decompression Performed ASAP, within 4 weeks of

determining need for surgery

*“Time-frame” is anchored in time from 1st provider visit related to PMNE complaints.



Most patients requiring a PMNE release alone can return to light duty work in approximately 3

weeks and regular duty work in approximately 6 weeks. A course of hand therapy may help

functional recovery and is particularly important for patients requiring tendon transfers or for

patients with residual weakness. These patients may return to light duty work in approximately

6-8 weeks and regular duty work in approximately 10-12 weeks.

VII. ELECTRODIAGNOSTIC WORKSHEET


The purpose of this worksheet is to help medical and nursing staff interpret electrodiagnostic

studies (EDS) that are done for injured workers. The worksheet should be used only when the

main purpose of the study is to evaluate a patient for PMNE. It should accompany but not

replace the detailed report normally submitted to the insurer. We encourage you to use the

electrodiagnostic worksheet below to report EMG results, but we will accept the results on a

report generated by your office system.


Worksheet for Proximal Median Nerve Electromyography

Electromyography criteria that confirm the diagnosis of PMNE

include evidence of denervation (e.g. increased insertional activity,

fibrillation potentials, positive sharp waves) in the following:

Abnormal

muscles

1. A muscle supported by the anterior interosseous nerve (flexor

pollicis longus, pronator quadratus, or radial aspect of the flexor

digitorum profundus)

OR

2. A median innervated muscle in the forearm (pronator teres, flexor

carpi radialis, flexor digitorum superficialis)

AND

3. A median innervated muscle in the hand (abductor pollicis brevis,

flexor pollicis brevis, or opponens pollicis)

AND

4. Needle EMG of at least one muscle supplied by the ulnar or radial

nerve should be normal.

*A true AIN syndrome would only need to meet criteria 1 and 4.

Claim Number:

Claimant Name:


Signed Date


References

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the proximal forearm. J Hand Surg [Am], 1994. 19(1): p. 121-6.

2. Hartz, C.R., Linscheid, R.L., Gramse, R.R., and Daube, J.R., The pronator teres

syndrome: compressive neuropathy of the median nerve. J Bone Joint Surg Am,

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5. Lacey, S.H. and Soldatis, J.J., Bilateral pronator syndrome associated with

anomalous heads of the pronator teres muscle: a case report. J Hand Surg [Am],

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6. Morris, H.H. and Peters, B.H., Pronator syndrome: clinical and

electrophysiological features in seven cases. J Neurol Neurosurg Psychiatry,

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7. Stal, M., Hagert, C.G., and Englund, J.E., Pronator syndrome: a retrospective

study of median nerve entrapment at the elbow in female machine milkers. J Agric

Saf Health, 2004. 10(4): p. 247-56.

8. Wiggins, C.E., Pronator syndrome. South Med J, 1982. 75(2): p. 240-1.

9. Bridgeman, C., Naidu, S., and Kothari, M.J., Clinical and electrophysiological

presentation of pronator syndrome. Electromyogr Clin Neurophysiol, 2007.

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10. Gross, P.T. and Jones, H.R., Jr., Proximal median neuropathies:

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11. Johnson, R.K., Spinner, M., and Shrewsbury, M.M., Median nerve entrapment

syndrome in the proximal forearm. J Hand Surg [Am], 1979. 4(1): p. 48-51.

12. Rehak, D.C., Pronator syndrome. Clin Sports Med, 2001. 20(3): p. 531-40.

13. Mysiew, W.J. and Colachis, S.C., 3rd, The pronator syndrome. An evaluation of

dynamic maneuvers for improving electrodiagnostic sensitivity. Am J Phys Med

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Eng, J., Carrino, J.A., and Chhabra, A., Magnetic resonance neurography of

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p. 623-32.

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peripheral neuropathies: role and impact of MR imaging on patient management.

Eur Radiol, 2008. 18(9): p. 1953-61.

16. Mujadzic, M., Papanicolaou, G., Young, H., and Tsai, T.M., Simultaneous

surgical release of ipsilateral pronator teres and carpal tunnel syndromes. Plast

Reconstr Surg, 2007. 119(7): p. 2141-7.

17. Trumble, T.E. and Budoff, J.E. American Society for Surgery of Hand. (2007).

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Acknowledgements

Acknowledgement and gratitude to all subcommittee members, clinical experts, and consultants

who contributed to this important guideline:

IIMAC Committee Members

Gregory T. Carter MD MS

Dianna Chamblin MD – Chair

G.A. DeAndrea MD MBA

Jordan Firestone, MD PhD MPH

Andrew Friedman MD

Subcommittee Clinical Experts

Christopher H. Allan MD

Douglas P. Hanel MD

Michel Kliot MD

Lawrence R. Robinson MD

Thomas E. Trumble MD

Nicholas B. Vedder MD

Michael D. Weiss MD

Consultants:

Terrell Kjerulf MD

Ken O’Bara MD

Eric M. Wall MD MPH

Department staff who helped develop and prepare this guideline include:

Gary M. Franklin MD, MPH, Medical Director

Lee Glass MD, JD, Associate Medical Director

Simone P. Javaher BSN, MPA, Occupational Nurse Consultant

Reshma N. Kearney MPH, Epidemiologist

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