Lumbar puncture: Difference between revisions
(→Source) |
|||
Line 10: | Line 10: | ||
==Procedure== | ==Procedure== | ||
[[File:Lumbar puncture lines.png|thumb|Surface markings for lumbar puncture. Blue dots = Iliac crests; line connecting them = intercristal (Tuffier's) line; intersection of the Tuffier's line and lumbar spine midline = L4 spinous process.]] | |||
#Sterile prep L3-L4 and L4-L5 interspaces; prepare and confirm correct tubes in numerical order | #Sterile prep L3-L4 and L4-L5 interspaces; prepare and confirm correct tubes in numerical order | ||
#*U/S can be used to ID interspaces in obese patients increasing your accuracy as much as 2.3 times<ref> Nomura, J, et al. A randomized control study of ultrasound-assisted lumbar puncture. J Ultrasound Med. 2007; 26:1341–8.</ref> | #*U/S can be used to ID interspaces in obese patients increasing your accuracy as much as 2.3 times<ref> Nomura, J, et al. A randomized control study of ultrasound-assisted lumbar puncture. J Ultrasound Med. 2007; 26:1341–8.</ref> |
Revision as of 20:08, 4 May 2015
Contraindications
- Infection at LP site
- Suspected spinal epidural abscess
Coagulopathy
Lumbar puncture if coagulopathic
- Tranfuse if platelets <25,000[1][2]
- INR >1.5
- Hemophilia, von Willebrand disease, other coagulopathies
- If hemophiliac, replace factor before LP
CT Before Lumbar Puncture
LP without CT is likely safe if:[3]
- History
- Age < 60
- Not immunocompromised
- No history of CNS disease
- No seizure within 1 week of presentation
- Physical Exam
- No altered level of consciousness
- Ability to answer two consecutive questions successfully
- Ability to follow two consecutive commands successfully
- Normal neurologic exam
- No altered level of consciousness
If none of the above, chance of normal ct is 97%; none of the patients herniated
CT findings that prohibit LP:[4]
- Midline shift
- Unequal pressures between the 3 cerebral compartments (left/right supretentorial compartments, posterior fossa)
- Intracerebral masses not causing midline shift
- Obstructive Hydrocephalus
- Enlargement of ventricles prox to lesions and normal ventricles distal (especially 4th ventricle)
- Basilar cisterns compressed
- Lateral/3rd ventricles may be small due to diffuse cerebral edema or enlarged due to obstr. hydroceph. +/- shift
- Posterior fossa mass
- Displacement/compression of 4th ventricle
Procedure
- Sterile prep L3-L4 and L4-L5 interspaces; prepare and confirm correct tubes in numerical order
- U/S can be used to ID interspaces in obese patients increasing your accuracy as much as 2.3 times[5]
- Positioning
- Pt on side: able to measure opening pressure
- Pt sitting: helpful for difficult habitus, but must move pt to measure opening pressure
- Needle selection
- 3.5 in atraumatic 22ga needle is ideal
- Needle >20ga almost doubles incidence of post-LP headache
- Anesthetize both superficial skin as well as along intended path of LP needle
- Insert needle with bevel facing the ceiling (if pt is on side)
- Opening pressure should be measured with pt on side with legs extended
- Collect 1mL in each tube
CSF Studies
Standard
- Tube 1: Gram Stain and culture
- Tube 2: Protein and glucose
- Tube 3: Cell count w diff
- Tube 4: Hold
Additional
- Cryptoccal ag
- India ink
- AFB PCR
- RPR, VRDL
- Fungal cx
- viral cx
- Herpes PCR
- LDH
- >40 suggests bacterial meningitis
- <40 suggests viral
Diagnosis
Measure | Normal | Bacterial | Aseptic (Viral) | Fungal | Tuberculosis | Subarachnoid hemorrhage | Neoplastic |
Appearance | Clear | Clear, cloudy, or purulent | Clear | Clear or opaque | Clear or opaque | Xanthochromia, bloody, or clear | Clear or opaque |
Opening Pressure (cm H2O) | 10-20 | >25 | Normal or elevated | >25 | >25 | >25 | Normal or elevated |
WBC Count^ (cells/µL) | 0-5^ | >100^ | 5-1000 | <500 | 50-500 | 0-5 (see correction section) | <500 |
% PMNs | >80-90% | 1-50%^^ | 1-50% | Early PMN then lymph | 1-50% | ||
Glucose | >60% of serum glucose | Low | Normal | Low | Low | Normal | Normal |
Protein^^^ (mg/dL) | < 45 | Elevated | Elevated | Elevated | Elevated | Elevated | >200 |
Gram Stain | Neg | Pos | Neg | India ink | Tb stain | Blood |
- ^Normal or lower WBC results may be found in immunocompromised, early, or partially treated (e.g. with oral antibiotics) bacterial menintigis, and those with tuberculosis meningitis
- ^^Lymph predominance may be found in patients with early bacterial meningitis or those that have been partially treated (e.g. with oral antibiotics)
- ^^^For unexplained elevations of protein, consider encephalitis, MS, Guillian Barre
Corrections
- WBC correction (for bloody tap)
- Simplified version (if peripheral WBC and RBC counts are within normal limits):
- Subtract 1 WBC for every 750 RBC in CSF
- Complex version (WBC and/or RBC not within normal limits):
- "WBCs added" = WBC(blood) x [RBC(CSF) / RBC(blood)]
- WBC counted/resulted - "WBCs added" = actual WBC
- Simplified version (if peripheral WBC and RBC counts are within normal limits):
- Protein correction (for bloody tap)
- For each 1000 RBC decrease protein value by 1mg/dl
Complications
- Post-Lumbar Puncture Headache
- Spinal Epidural Hematoma
See Also
Further Reading
- Straus, S. et al. How Do I Perform a Lumbar Puncture and Analyze the Results to Diagnose Bacterial Meningitis?[6]
References
- ↑ Howard SC, Gajjar A, Ribeiro RC, et al. Safety of lumbar puncture for children with acute lymphoblastic leukemia and thrombocytopenia. JAMA 2000; 284:2222–2224
- ↑ Vavricka SR, Walter RB, Irani S, Halter J, Schanz U. Safety of lumbar puncture for adults with acute leukemia and restrictive prophylactic platelet transfusion. Ann Hematol 2003; 82:570–573
- ↑ Computed Tomography of the Head before Lumbar Puncture in Adults with Suspected Meningitis. NEJM 2001; 345; 1727-33
- ↑ Emergency Radiology: Case Studies Schwartz
- ↑ Nomura, J, et al. A randomized control study of ultrasound-assisted lumbar puncture. J Ultrasound Med. 2007; 26:1341–8.
- ↑ Straus, S. et al. How Do I Perform a Lumbar Puncture and Analyze the Results to Diagnose Bacterial Meningitis? http://jama.jamanetwork.com/data/Journals/JAMA/5048/JRC60004.pdf