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4. Treatment of elevated CSF pressure in selected

patients with benign intracranial hypertension.

5. Removal of exudate or blood from subarachnoid space.

The procedure should be done with a stylette inside to

avoid implantation of skin, which may form dermoid cyst

in the spinal canal. A manometer and three-way stopcock

should be attached to the needle, so that initial pressure

can be accurately measured and CSF removed under

control.

Cerebrospinal and Other Body Fluids 383

Complications of Lumbar Puncture

1. Production of cerebellar pressure cone in patients with

increased intracranial pressure.

2. With spinal cord tumor, progression of paresis to

paralysis may follow lumbar puncture.

3. Introduction of infection by:

• Passing the needle through superficial or deep

sepsis in the lumbar region.

• Improperly sterilized equipment.

• Poor technique.

• Development of dermoid cyst if lumbar puncture

is performed without the stylette.

• Postpuncture headache resulting from leakage of

CSF (incidence can be decreased by using a small

bore needle and keeping the patient horizontal

for 24 hours).

4. In infants death due to asphyxiation caused by

restraint or tracheal obstruction from pushing the

head forward.

Elective lumbar puncture should be performed in the

morning rather than late afternoon or evening.

CSF Rhinorrhea and Otorrhea

Fluid coming through ear or nose may be CSF. Confirmation

can be done by inserting a glucose-oxidase strip into nose

or ear for 5 minutes: a 2+ or 3+ reaction indicates glucose

present, is considered evidence of CSF rhinorrhea or

otorrhea (30% false positives). Normal concentration of

glucose in nasal secretions is 10 to 25 mg%. If the test is

inconclusive, cotton may be placed in the nasopharynx

and radioactive iodinated serum albumin (RISA) injected

into the lumbar subarachnoid space, the cotton is left in

place for 12 hours and then counted for gamma radiation.

CSF Pressure

If the opening pressure exceeds 180, reassure the patient

and straighten the leg, back and neck and to make sure

there is no breath holding or abdominal or jugular

compression. If the pressure then falls to normal, it is

probable that the initial elevation was artefactual. CSF

pressure is directly related to pressure in the jugular and

vertebral veins, which communicate with the intracranial

dural sinuses and spinal dura. Hence, CSF pressure is

decreased with circulatory collapse and increased with

congestive heart failure, obstruction of the superior vena

cava, straining, breath holding, or pressure against the

abdomen (e.g. obese patients in lying position).

Pathologically Increased Pressure is Usually Due to:

¾ Inflammation of the meninges

¾ A space-occupying lesion (SOL), such as a tumor,

abscess, cerebral-edema or intra-cerebral hemorrhage.

If the Initial Pressure Exceeds 200 mm. CSF, not more

than 1–2 mL of fluid should be removed, a 25 to 50% fall

in pressure after removing 1–2 mL suggests cerebellar

herniation or spinal cord compression above the puncture

site. STOP removing CSF. Observe the patient for several

hours. Usually, three 2 mL samples are taken in sterile

tubes and labeled sequentially.

If Initial Pressure is Normal and there is Clinical Suspicion

of Subarachnoid Block, Queckenstedt’s Test may be done:

Normally if both jugular veins are manually compressed,

CSF pressure rapidly returns to normal when compression

ceases. With sinus thrombosis, obstruction at the foramen

magnum, or a mass lesion in the spinal canal, the rise of

CSF pressure may be decreased/delayed—this is a positive

Queckenstedt’s test. In such cases, normal variations in

pressure due to respiration will be diminished/absent

but straining or abdominal compression should result in

increased CSF pressure (due to vertebral vein congestion)

if the needle is placed correctly.

Almost 80% of patients with cord compression have a

positive Queckenstedt’s test. Lesions responsible for cord

compression include:

¾ Herniated intervertebral disc

¾ Vertebral fracture

¾ Extradural abscess

¾ Adhesions due to pachymeningitis

¾ Neoplasms (primary or metastatic) involving vertebrae,

meninges, or spinal cord.

Gross Examination

Normal CSF is crystal clear.

Evaluate color by holding the CSF tube beside a distilled

water tube against a clean white paper. If a pale yellow or

pink color is noted—centrifuge the sample at high speed

for 5 minutes and examine the supernatant visually.

Xanthochromia (pale pink to pale orange or yellow color

in supernatant) is usually graded from 1 to 4 and may be

due to:

¾ CSF protein > 100 mg%

¾ Traumatic tap with lysis of erythrocytes due to detergent

in needle or sample tube

¾ Bilirubinemia (both conjugated bilirubin in adults

and unconjugated bilirubin in neonates may pass the

blood-CSF barrier)

¾ Intracerebral or subarachnoid hemorrhage

¾ Contamination of CSF by iodine/merthiolate used to

disinfect the skin

¾ Carotenemia

¾ Melanin in CSF due to meningeal melanosarcoma.

384 Concise Book of Medical Laboratory Technology: Methods and Interpretations Two to twelve hours after a subarachnoid hemorrhage,

pale orange xanthochromia appears in CSF in 90% cases.

Yellow xanthochromia due to conversion of hemoglobin

to bilirubin within 2 to 4 days. The orange xanthochromia

of oxyhemoglobin usually disappears in 4 to 8 days, while

yellow xanthochromia due to bilirubin typically persists for

12–40 days.