It is done for two purposes:
1. Taking a CSF sample for analysis
2. CSF drainage and pressure reduction
0 It is most commonly taken from the L3-L4 range in adults. This level is at the level of the iliac crest.
0 Second most frequently done from the L4-L5 range.
0 All ranges from L2/L3 to L5/S1 are safer since the spinal cord ends in L1.
0 Skin - adipose tissue -supraspinous ligament - interspinous ligament - epidural space -dura mater - arachnoid meter - subarachnoid space is reached.
Indications
CSF pressure measurement
Cell, chemical and bacteriological examinations (subarachnoid hemorrhages, meningitis, encephalitis)
Administration of radiopaque material for myelography, cisternography
For therapeutic purposes: Chemotherapy (eg cytosine arabinoside injection)
Contraindications
Suspected intracranial mass
Local infection at the LP site (the procedure must be sterile)
Thrombocytopenia and PT-PTT prolongation
Suspicion of increased intracranial pressure
Diseases for which intracranial hypertension is not contraindicated:
Meningitis
Subarachnoid hemorrhage
Benign intracranial hypertension
In most cases, LP should be performed after the space-occupying lesion has been ruled out by CT.
Complications
The most common complication is headache {33%)
Tonsillar herniation
Epidural bleeding
LP Results: Pressure: 180 - 200 mm Hp (in the Subarachnoid range), appearance: clear, cells: Absent (5 mononuclear lymphocytes/ml, O erythrocytes/ml), protein: 15 - 40 mg/dl, glucose: Simultaneous when assessing blood sugar should be taken. If it is less than 2/3 of the blood value, it is pathological.
Clinical pictures seen in CNS Infections
1- Meningitis is the inflammation of the meninges. Neck stiffness, fever are seen. Meningeal thickening and enhancement occur on contrast-enhanced CT.
2- Encephalitis is the inflammation of the brain parenchyma. Seizures, changes in consciousness, fever are observed.
CT is normal in the early period.
3- abscess: It is the circumscribed inflammation of the brain parenchyma.
Most common cause in adults: Chronic otitis is most common in the temporal lobe through the neighborhood.
Most common cause in child: Cyanotic congenital heart diseases; most common location middle cerebral artery distribution
4- Vasculitis. It is an inflammation of vascular structures.
|
|
Increasing
Cell |
Protein |
glucose |
|
bacterial |
neutrophil |
Increases |
decreases |
|
TB |
lymphocyte |
Increases |
decreases |
|
viral |
lymphocyte |
Very Slightly Increased or Normal Meningitis CSF
findings |
Normal |
Xanthochromic CSF
CSF is yellow.
1. Subarachnoid hemorrhage: Subarachnoid hemorrhage 4-5 hours ago
2. Medulla spinalis compression: Increases CSF protein too much
3. Those that increase protein in tuberculous meningitis CSF fluid:
Meningitis (including carcinomatous meningitis)
Bloody CSF (subarachnoid and intraventricular hemorrhage)
Compression of the spinal cord
Guillain-Barré syndrome
Diabetic radiculoneuropathy
Myxedema
Those that reduce protein in CSF fluid:
1. CSF leak due to previous LP
2. Traumatic dural fistula leak
3. Pseudotumor cerebri (may also be normal)