Lumbar puncture: Difference between revisions
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− | == |
+ | ==Contraindications== |
− | * |
+ | *Increased intracranial pressure, with focal neurological deficits, new seizures, or papilledema (CT head first; see Investigations, below) |
− | * |
+ | *Infection at the procedure site |
− | * |
+ | *Coagulopathy |
− | ** |
+ | **Platelets <30-40 |
− | ** |
+ | **INR ≥1.4-1.6 |
− | ** |
+ | **[[Hemophilia]] |
− | ** |
+ | **Anticoagulation |
+ | ***Within 4 hours of prophylactic [[low molecular weight heparin]] (LMWH) |
||
+ | ***Within 24 hours of therapeutic [[LMWH]] |
||
+ | ***Within 7 days of [[clopidogrel]] (but no delay for [[aspirin]]) |
||
− | == |
+ | ==Procedure== |
− | * |
+ | *Position appropriately: lateral decubitus or sitting and leaning over a table |
− | * |
+ | *Landmark using posterior superior iliac crests (PSIS) (marks L4) |
− | ** |
+ | **Can go above (L4/L5 space) or below (L3/L4 space) |
− | * |
+ | *Inset spinal needle in the midline |
− | * |
+ | *Measure opening pressure |
− | == |
+ | ==Investigations== |
− | * |
+ | *Consider INR/PTT if concern about coagulopathy |
− | * |
+ | *Consider platelet count (should be >100) |
− | * |
+ | *Consider CT head if focal neurological signs, papilledema, GCS ≤12 |
+ | **IDSA: immunocompromised, history of CNS disease (including stroke and mass lesion), or new, uncontrolled, or continuous seizures |
||
− | == |
+ | ==Complications== |
− | * |
+ | *Local pain |
− | * |
+ | *Post-LP headache, better when supine |
− | ** |
+ | **Treat with caffeine, fluids, and acetaminophen |
− | * |
+ | *Brief radicular pain |
− | * |
+ | *Rare: |
− | ** |
+ | **Spinal epidural hematoma |
− | ** |
+ | **Bacterial meningitis or spinal abscess |
− | ** |
+ | **Cerebral herniation |
− | == |
+ | ==Interpretation== |
+ | {| class="wikitable" |
||
− | {| |
||
− | ! |
+ | !Etiology |
− | ! |
+ | !Gram stain |
− | ! |
+ | !Cell count |
− | ! |
+ | !CSF glucose |
− | ! |
+ | !CSF protein |
|- |
|- |
||
− | | |
+ | |[[Bacterial meningitis]] |
− | | |
+ | |Positive in 60-80% |
− | | |
+ | |Elevated >1000 neutrophils |
− | | |
+ | |Reduced <0.4 CSF:serum |
− | | |
+ | |Elevated >1g/L |
|- |
|- |
||
− | | |
+ | |[[Viral meningitis]] |
− | | |
+ | |Negative |
− | | |
+ | |Moderate elevation <100 lymphocytes |
− | | |
+ | |Normal or mildly reduced |
− | | |
+ | |Normal or mildly elevated |
|- |
|- |
||
− | | Fungal or tuberculous meningitis |
+ | |[[Fungal meningitis|Fungal]] or [[tuberculous meningitis]] |
− | | |
+ | |Negative, except for [[Cryptococcus]] on [[India ink]] or TB on acid-fast stain |
− | | |
+ | |Moderate elevation, usually lymphocytes |
− | | |
+ | |Often very low |
− | | |
+ | |Elevated |
|} |
|} |
||
− | * |
+ | *Correction for a bloody tap is 1 excess WBC for every 700 RBCs |
− | * |
+ | *Lymphocytosis may be seen in bacterial meningitis if [[Listeria]] infection or prior antibiotics |
− | * |
+ | *[[Xanthochromia]] suggests subarachnoid hemorrhage |
+ | *[[Hypoglycorrhachia]] refers to low CSF glucose |
||
− | === |
+ | ===Interpretation After Antibiotics=== |
− | * |
+ | *Glucose increases first, then protein, and both are often normalized within 12 hours |
− | * |
+ | *WBC normalizes last, and can still be useful even the following day |
− | == |
+ | === Opening Pressure === |
+ | * Usual range is 5 to 20 cm H<sub>2</sub>O |
||
⚫ | |||
+ | * See [[Increased intracranial pressure#Differential Diagnosis|causes of increased intracranial pressure]] |
||
+ | |||
+ | === Protein === |
||
+ | |||
+ | * May be increased by disruption of the blood-brain barrier (most commonly), intracranial synthesis of IgG, or impaired CSF resorption of proteins by the arachnoid villi |
||
+ | * Highly suggestive of CNS disease |
||
+ | |||
+ | === Correction for Traumatic Tap === |
||
+ | |||
+ | * If increased RBCs are seen, may need to adjust |
||
+ | * Allow 1 WBC for every 700-1000 RBCs |
||
+ | * Allow 0.01 mg/mL protein for every 1000 RBCs |
||
+ | |||
+ | ==Further Reading== |
||
+ | |||
⚫ | |||
[[Category:Neurology]] |
[[Category:Neurology]] |
Latest revision as of 08:11, 3 November 2021
Contraindications
- Increased intracranial pressure, with focal neurological deficits, new seizures, or papilledema (CT head first; see Investigations, below)
- Infection at the procedure site
- Coagulopathy
- Platelets <30-40
- INR ≥1.4-1.6
- Hemophilia
- Anticoagulation
- Within 4 hours of prophylactic low molecular weight heparin (LMWH)
- Within 24 hours of therapeutic LMWH
- Within 7 days of clopidogrel (but no delay for aspirin)
Procedure
- Position appropriately: lateral decubitus or sitting and leaning over a table
- Landmark using posterior superior iliac crests (PSIS) (marks L4)
- Can go above (L4/L5 space) or below (L3/L4 space)
- Inset spinal needle in the midline
- Measure opening pressure
Investigations
- Consider INR/PTT if concern about coagulopathy
- Consider platelet count (should be >100)
- Consider CT head if focal neurological signs, papilledema, GCS ≤12
- IDSA: immunocompromised, history of CNS disease (including stroke and mass lesion), or new, uncontrolled, or continuous seizures
Complications
- Local pain
- Post-LP headache, better when supine
- Treat with caffeine, fluids, and acetaminophen
- Brief radicular pain
- Rare:
- Spinal epidural hematoma
- Bacterial meningitis or spinal abscess
- Cerebral herniation
Interpretation
Etiology | Gram stain | Cell count | CSF glucose | CSF protein |
---|---|---|---|---|
Bacterial meningitis | Positive in 60-80% | Elevated >1000 neutrophils | Reduced <0.4 CSF:serum | Elevated >1g/L |
Viral meningitis | Negative | Moderate elevation <100 lymphocytes | Normal or mildly reduced | Normal or mildly elevated |
Fungal or tuberculous meningitis | Negative, except for Cryptococcus on India ink or TB on acid-fast stain | Moderate elevation, usually lymphocytes | Often very low | Elevated |
- Correction for a bloody tap is 1 excess WBC for every 700 RBCs
- Lymphocytosis may be seen in bacterial meningitis if Listeria infection or prior antibiotics
- Xanthochromia suggests subarachnoid hemorrhage
- Hypoglycorrhachia refers to low CSF glucose
Interpretation After Antibiotics
- Glucose increases first, then protein, and both are often normalized within 12 hours
- WBC normalizes last, and can still be useful even the following day
Opening Pressure
- Usual range is 5 to 20 cm H2O
- See causes of increased intracranial pressure
Protein
- May be increased by disruption of the blood-brain barrier (most commonly), intracranial synthesis of IgG, or impaired CSF resorption of proteins by the arachnoid villi
- Highly suggestive of CNS disease
Correction for Traumatic Tap
- If increased RBCs are seen, may need to adjust
- Allow 1 WBC for every 700-1000 RBCs
- Allow 0.01 mg/mL protein for every 1000 RBCs
Further Reading
- Straus S, et al. How Do I Perform a Lumbar Puncture and Analyze the Results to Diagnose Bacterial Meningitis? JAMA. 2006;296(16):2012-2022.