PERIPHERAL NEUROPATHY

Prof.Dr/ Ahmed Gamal Azab

Definition

It is inflammation or degeneration of the peripheral or cranial nerves resulting in impairment of conduction along these nerves leading to motor , sensory and/or autonomic manifestations.

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Classification

1- Mononeuropathy : affection of a single nerve trunk in one limb.

2- Mononeuropathy multiplex : affection of more than one nerve trunk in the same limb.

3- Polyneuropathy : affection of more than one nerve trunk in more than one limb.

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Causes of mononeuropathy & mononeuropathy multiplex

1- Traumatic : - Compression by a bony fragment or callous formation.

- Dislocation.

- Wrong injection into a nerve .

- Crossed leg palsy & Saturday night paralysis.

2- Infective : - Leprosy – Herpes zoster.

3- Vascular : Polyarteritis nodosa .

4- Metabolic : Diabetes mellitus.

Causes of Polyneuropathy

A- Heridofamilial : - Peroneal muscle atrophy . - Hypertrophic interstitial polyneuropathy. - Refsum disease.B- Acquired :1- Infective : - Viral : mumps , measles. - Bacterial : Typhus , Typhoid , Tetanus. - Mycobacterial : Leprosy.

Acquired Polyneuropathy ( cont.. )

2- Toxic : - Inorganic : lead, copper, arsenic, antimony, gold…. ( all heavy metals ). Organic : alcohol, insecticides.

3- Metabolic & Endocrinal : Diabetes mellitus, uremia, amyloidosis, acromegaly,

myxoedema. 4- Nutritional : Pellagra, Beri-beri, subacute combined

degeneration.5- Iatrogenic : INH, sulphonamides, phenytoin, vincristine.6- Autoimmune : Guillain Barre syndrome , collagen vascular

disorders. 7- Paraneoplastic : bronchogenic carcinoma , lymphoma.

Pathology

1- Axonal neuropathy : in which the nerve cell body & axon are primarily affected.

- It shows mild reduction in the nerve conduction velocity but regeneration is slow.

- It occurs in traumatic, ischemic, nutritional and toxic causes.

Pathology ( cont.. )

2- Demyelinating neuropathy :

- In which Schwann cell is affected w/out involvement of the axon.

- It shows marked reduction of the conduction velocity, but with rapid regeneration.

- occurs in infective & metabolic causes.

Clinical Picture of Polyneuropathy

Regardless of the cause, It is one of various combinations of motor, sensory and/or autonomic manifestations .

The manifestations are usually bilateral, symmetrical, distal more than proximal, involving the lower limbs earlier than the upper limbs.

Clinical Picture ( cont…)

A- Sensory manifestations :

1- Subjective : pain, parasthesia ( numbness, tingling ) at the limbs periphery.

2- Objective : glove & stocking hyposthesia + distal deep sensory loss > sensory ataxia.

Clinical Picture ( cont…)

B- Motor manifestations :LMNL ( wasting, weakness, hypotonia, hyporeflexia ).

C- autonomic manifestations :

- Vasomotor : coldness , cyanosis .

- Trophic : loss of hair, brittle nails , trophic ulcers (in severe cases).

Investigations

1- EMG & NCS : reduced nerve conduction velocity.

2- Nerve biopsy : usually the sural nerve.

3- To detect the cause: Bl.sugar, tests for collagen vascular disorders, s.creatinine.

Diabetic Neuropathy

1- Diabetic sensorimotor polyneuropathy :-Common in insulin-dependent diabetics.-Sensory > motor .-Burning pain, stock, glove hyposthesia, impaired deep sensation.-Lost ankle reflex.-Autonomic neuropathy may occur.-In long standing cases > distal wasting, weakness may occur. Pathogenesis (still controversial) : -in elderly patients it may be an ischemic neuropathy. -in young patients > it may be due to a metabolic factor (hyperglycemia >

sorbitol accumulation > decreased myoinositol uptake by nerve fibres > impaired impulse conduction) .

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Diabetic neuropathy( cont…)

2- Diabetic autonomic neuropathy:

-Sweating, diarrhea, postural hypotension, impotence .

3- Diabetic proximal neuropathy :

-Common in non-insulin dependent .

-Start by pain front of the thigh followed by proximal leg weakness, lost knee reflex.

Diabetic neuropathy( cont..)

4- Diabetic mononeuropathy: - Affects peripheral or cranial nerves. - Nerves vulnerable to compression are the commonest ,such

as : Median, ulnar , radial, common peroneal and lateral cutaneous nerve of the thigh.

- Ocular nerves are commonly affected(improve in 3-6 months).5- Diabetic truncal neuropathy : -Recurrent attacks of truncal pain w/sensory deficit in the

distribution of a single thoracic root. -Spontaneous recovery occurs in few months.

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Treatment of diabetic neuropathy

1- Proper control of diabetes.2- Pancreatic transplantation : minor recovery

occurs 3.5 years post transplant.3- Carbamazepine or Gabapentin for burning

pain & Amitriptylline for aching pain.4- Vitamins B1,B6,B12 ( help regeneration ).5- Vasodilators.6- Physiotherapy for motor weakness.

Peroneal Muscle Atrophy ( HMSN ) = ( Charcot-Marie-Tooth disease )

Type l : the commonest type, autosomal dominant, occurs in the first decade .

- Starts by distal leg weakness & wasting w/ inverted champagne-bottle appearance ( as it involves the muscles transversely, does not extend above the junction between lower and middle third of the thigh).

- Later on, there is hand weakness.- Stocking, glove hyposthesia, pes cavus, - There may be associated tremors.

HMSN ( cont…)

Type ll : less common, autosomal dominant , onset in the second decade.

- Pes cavus, hand weakness and sensory loss are less frequent.

Type lll: uncommon, autosomal recessive, starts in infancy > delayed walking.skeletal deformities.

Treatment :- Physiotherapy. - Ankle splints for foot drop.- Ankle splints for foot drop.

Diphtheritic Neuropathy.

Clinical picture : 1-Starts by true bulbar palsy (within few days) followed by >

2- Paralysis of eye accomodation ( ciliary muscle paralysis ) > blurred near vision.

3-Generalized sensorimotor polyneuropathy. 4-Diaphragmatic paralysis. Prognosis : - Good if the child survives.- Bulbar & accomodation weakness improve within 6 weeks.- Polyneuropathy recovery takes months.

Diphtheritic neuropathy ( cont…)

Treatment :

- Penicillin G : 600,000 u/12 hours for 14 days.

- Diphtheritic antitoxin : should be given early as 100,000 u IM.

- Assisted ventillation if need .

Leprotic Neuropathy

- Organism : Mycobacterium leprae .- Long Incubation period ( about 3.5 years ).- Insidious onset. Types : 1- Lepromatous : nodules over the face > leonine facies.2- Tuberculoid : maculo-anaesthetic skin patches, trophic ulcers.- It may be a mono or polyneuropathic affection.- Commonly affacts the facial, sensory 5th, great auricular, ulnar and common

peroneal nerves.- Thickened affected nerves.- Sensory > motor affection.Treatment : - Dapsone 100mg/day + Rifampicin 600 mg/day ( for 1-2 years ).- Nerve grafting : for severe mononeuropathy with trophic ulcers.

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Guillain-Barre syndrome ( acute post-infective polyradiculoneuropathy )

Aetiology (theories) :

1- Post infection : 50% of cases have preceding respiratory or GIT viral infection.

2- Post vaccination : following vaccination against Swine influenza virus.

3- Lymphoma (Hodgkin disease).

4- Autoimmune theory.www.MansFans.com

Guillain-Barre ( cont…)

Clinical picture :- Initial febrile illness.- Usually starts in LLs, then ascends to ULs.- Proximal > distal, bilateral symmetrical affection.- Bilateral LMNL 7th paralysis.- Bulbar weakness, followed by respiratory muscle

paralysis.- Glove , stocking hyposthesia- Papilloedema (due to increased CSF proteins >

diminished absorption.).www.MansFans.com

Guillain-Barre ( cont…)

Prognosis :

- Recovery in 3-6 months.

- May be with mild residue in 40% of cases.

- Survival for 8 weeks > good prognosis.

Investigations :

- CSF proteins > 2 g/L with normal cell count.

Guillain-Barre (cont…)

Treatment:

1- Nasogastric tube feeding for bulbar palsy.

2- S.C heparin to guard against DVT.

3- Assisted ventillation.

4- Plasmapheresis ( must be done in the first 2 weeks).

5- IVIG : 0.4 g/Kg /day for 5 succesive days. www.MansFans.com