Clinical Skills:Clinical Skills:

Lumbar PunctureLumbar Puncture

ConsiderationsConsiderations

• Why is an LP Being Done?• Is this the Only Test Available?• What Positive Information is

Expected?• Is the Patient Stable?

IndicationsIndications• Diagnostic

• Infection• Subarachnoid Hemorrhage• Multiple Sclerosis

• Therapeutic• Neoplasm• Benign intracranial hypertension (BIH)

• Incidental• Myelography : is a type of radiographic

examination that uses a contrast medium to detect pathology of the spinal cord

ContraindicationsContraindications• Suspected Increase in ICP

• Exception: therapeutic use of lumbar puncture to reduce ICP • Suspected Spinal Cord Compression• Infection at the Site of an LP• Coagulopathy.

Abnormal respiratory pattern Hypertension with bradycardia and deteriorating

consciousness Vertebral deformities , in hands of an inexperienced

physician.

Normal CSF ValuesNormal CSF Values• Appears to be clear and colorless• Opening Pressure ~ 120 mm/H20• Protein level ~ 35 mg%• Glucose level ~ 60 mg %• (60% of serum glucose)

• Cells < 5 lymphocytic/monocytic

CSF Profile’sCSF Profile’s

Pressure Cells Protein Glucose

Bacterial Meningitis

(PMN’s)

to

Viral Meningitis

N to

to (Mono’s)

N

TECHNIQUE

Preparation — An LP can be performed with the patient in the lateral recumbent position or sitting upright.

The lateral recumbent position is preferred because it allows accurate measurement of the opening pressure

Equipment Most CSF trays come with:

– Anesthetic such as: Topical - Zylocaine cream Lidocaine 1% with 25 gauge needle and

syringe– Povidone-iodine solution & sponge

wand– Drapes, gauze, and bandages– Manometer, stopcock and tubing in

non-infant kits

Equipment Spinal needle, usually 22 gauge

– 1.5 in for < 1 yr– 2.5 in for 1 year to middle

childhood– 3.5 in for older children and

adolescents– Larger for large adolescents

Atraumatic needles, less spinal headaches

Lateral Decubitus Position

Apply topical anesthetic 30-45 min prior to procedure Spinal cord ends at L1-L2, so sites for puncture are located at L3-L4

or L4-L5 Restrain patient in lateral decubitus position

– Maximally flex spine without compromising airway– Keep alignment of feet, knees and hips– Position head to left if right handed or vice versa

Preparation for the LPPreparation for the LP (one)(one)

Preparation for the LPPreparation for the LP (two)(two)

Aseptic technique

The overlying skin should be cleaned with alcohol and a disinfectant such as povidone-iodine or chlorhexidine (0.5 percent in alcohol 70 percent);

the antiseptic should be allowed to dry before the procedure is begun. 

Procedure

Insert spinal needle with stylet with bevel up to keep cutting edge parallel with nerve and ligament fibers

Procedure

Aim towards umbilicus directing needle slightly cephalad

Hold needle firmly

Procedure

A “pop” of sudden decrease in resistance indicates that ligamentum flavum and dura are punctured

Remove stylet and check for flow of spinal fluid

Procedure If no fluid, then:

– Rotate needle 90°– Reinsert stylet and advance needle slowly checking frequently for

CSF Jugular vein compression can increase CSF pressure in low flow

situations If bony resistance is felt immediately then you are not in the spinal

interspace If bony resistance is felt deeply, then withdraw needle to the skin

surface and redirect more cephalad and increase patient flexion If bloody fluid that does not clear or that clots results, then withdraw

needle and reattempt at a different interspace

Manometry

When CSF flows, attach manometer to obtain opening pressure if desired

Pressure can only be accurately measured in lateral decubitus position and in the relaxed patient

Attach manometer with a 3-way stopcock when free flow of CSF is obtained

Read column when highest level is achieved and respiratory variation is noted

Complications Headache

– Uncommon in < 10 y/o Apnea (central or obstructive) Back pain

– Occasionally with short-lived referred limp– Disc herniation if needle advanced too far

Bleeding or fluid leak around spinal cord Infection, pain, hematoma Subarachnoid epidermal cyst Ocular muscle palsy (transient) Nerve Trauma Brainstem herniation

Procedure

Collect 1ml of CSF in each of 3 vials for:– Tube 1: culture & gram stain– Tube 2: glucose, protein– Tube 3: cell count & differential– and extra CSF if desired for other lab tests

Check closing pressure with manometer, if desired Reinsert stylet and remove needle in one quick motion Cleanse back and cover puncture site

Sitting Position Restrain infant in the seated position

with maximal spinal flexion– Hold infant’s hands between flexed

legs with one hand and flex head with the other hand

Drape patient below buttocks and fenestrated drape opening over puncture site

Insert needle so bevel is parallel to spinal cord (Bevel left or right)

Cannot measure pressure accurately in this position

Paramedian (Lateral) Approach

Use for patients who have calcifications from repeated LPs or anatomic abnormalities

Needle passes through erector spinae muscles, and ligamentum flavum

– Bypasses supraspinal and interspinal ligaments

Less incidence of spinal headache

Spinal Headache Most common complication Risk factors: female, age 18-30, lower BMI, hx of

HA, prior spinal HA Can last hours to weeks

Treatment:– Supine position for at least 2 hours – Hydration– Caffeine either PO or IV– Epidural blood patch

Spinal Headache Prevention

Can avoid by:– Passing needle bevel parallel to longitudinal

fibers of dura– Replacing stylet before removing needle– Using small diameter needles– Using atraumatic needles

Bed rest or PO intake after LP does not reduce incidence of headache

Nerve Root Trauma/Irritation

Can feel electric shocks or dysesthesias Back pain can persist for months

– Consider disc herniation Rarely permanent Withdraw needle immediately If pain or motor weakness persists, start corticosteroids Electromyogram/nerve conduction velocity studies should

be scheduled if pain persists

Herniation

Manifests initially as altered mental status, followed by cranial nerve abnormalities and Cushing triad

May be rapidly fatal. Immediately remove needle and raise the head of bed to

30-45° improve venous return from the brain. Mannitol or 3% Saline Intubate patient and hyperventilate Emergent neurosurgical consult

Thanks for attention