Cerebrospinal Fluid Analysis

Indications and Contraindications

• Lumbar puncture is contraindicated in patients with increased intracranial pressure due to space-occupying lesions, local skin infection at the puncture site, coagulopathy, and hemodynamic instability, as these conditions significantly increase the risk of serious complications including cerebral herniation and hemorrhage 1, 2
• Clinical suspicion of spinal cord compression is a contraindication for lumbar puncture 2
• Absolute contraindications for lumbar puncture include increased intracranial pressure with evidence of mass lesion, infection at the puncture site, severe cardiorespiratory compromise, and uncorrected coagulopathy, as stated by the American Heart Association guidelines 3
• Signs requiring cranial imaging before LP include focal neurologic deficits, new-onset seizures, severely altered mental status, severely immunocompromised state, and papilledema, which are indicators of raised intracranial pressure 1, 2
• Indications for lumbar puncture include unexplained altered consciousness or focal neurologic signs in febrile patients, moderate to severe impairment of consciousness (GCS score less than 13), and focal neurological signs, as recommended by the Infectious Diseases Society of America, the British Infection Association, and the British Infection Association 4, 5

Pre-Procedural Considerations

• For patients on heparin, adequate reversal with protamine is required before LP, and for patients on warfarin, reversal with vitamin K, prothrombin complex concentrate, or fresh frozen plasma is mandatory 5
• Consider platelet transfusion for counts <50 × 10⁹/L 2
• Aspirin monotherapy can be continued for central neuraxial procedures when the benefit-risk ratio is favorable, as stated by the French Working Group on Perioperative Haemostasis (GIHP) and the French Study Group on Thrombosis and Haemostasis (GFHT) 6
• Concomitant use of other antiplatelet agents or anticoagulants, as well as coagulopathy or other hemostatic abnormalities, increases the risk of bleeding complications 6
• P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) should be discontinued 5-7 days before the procedure, while aspirin can be continued 6

Procedure and Technique

• The procedure should be performed by an experienced operator to reduce bleeding risk, and consider ultrasound guidance to reduce the risk of vascular puncture 6
• Single-puncture technique is preferable to reduce bleeding risk, if possible 6
• Clinical assessment, not cranial CT, should be the primary determinant of lumbar puncture safety, as recommended by the British Infection Association 5
• Lumbar punctures should be performed with needles that meet the standards set by the National Patient Safety Agency 2, 5

Cerebrospinal Fluid Analysis

• Bacterial meningitis is typically characterized by a cerebrospinal fluid (CSF) protein level of >220 mg/dL, according to the American College of Critical Care Medicine 4
• Guillain-Barré syndrome is often associated with albumino-cytological dissociation, which is elevated protein with a normal cell count, as stated by the European Academy of Neurology 7
• Leptomeningeal metastasis is commonly characterized by elevated protein levels (>50 mg/dL) in 56-91% of cases, as reported by the European Society for Medical Oncology 8
• The following table summarizes the characteristic CSF findings in different conditions:

• Low glucose (<35 mg/dL) and low CSF:plasma glucose ratio (<0.23) strongly suggest bacterial meningitis, with measurement of concurrent plasma glucose recommended for accurate interpretation, as stated in the Journal of Infection guidelines 9
• Elevated opening pressure (>200 mm H₂O) is common in meningitis, encephalitis, and leptomeningeal metastasis, according to the Annals of Oncology guidelines 8

Complications and Management

• Post-dural puncture headache (PDPH) is a common complication, with an incidence of up to 35% with conventional needles, significantly reduced with atraumatic needles, and characteristics including positional headache worsening when upright, according to the American Headache Society guidelines 3
• Prevention of PDPH includes using atraumatic needles, smaller gauge needles, and replacing the stylet before withdrawal, with management involving hydration, caffeine, analgesics, and severe cases requiring epidural blood patch, as recommended by the American Society of Regional Anesthesia and Pain Medicine guidelines 3