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Lumbar Puncture What you need to know (and what I wish I had ). Mark Keezer, MDCM, FRCPC MSc candidate, Epidemiology , McGill University Epilepsy Fellow, National Hospital for Neurology & Neurosurgery, London, UK (to begin in September, 2013 ). NEJM video.
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Lumbar PunctureWhat you need to know (and what I wish I had) Mark Keezer, MDCM, FRCPC MSc candidate, Epidemiology, McGill University Epilepsy Fellow, National Hospital for Neurology & Neurosurgery, London, UK (to begin in September, 2013)
NEJM video http://www.nejm.org.proxy1.library.mcgill.ca/doi/full/10.1056/NEJMvcm054952
Outline • Preparation • The Procedure • Interpreting the Results • PLPHA
1. Preparation Consent Antiplatelets Labs Neuro-imaging Supplies needed
Patient consent • Back pain • Radicular pain • Hemorrhage • Infection • PLPHA (~40%)
Prospective cohort • 924 orthopedic patients undergoing spinal or epidural anesthesia • 39% receiving antiplatelets • 2% receiving prophylactic heparin • 0 epidural hematomas • No relationship with minor hemorrhage during procedure Horlocker TT et al. Preoperative antiplatelet therapy does not increase the risk of spinal hematoma associated with regional anesthesia. AnesthAnalg 1995;80:303-9.
Coags& platelets • Platelets > 50,000 • INR <1.5 • Guidelines at the Preston Robb day centre • Currently it seems it is acceptable to not verify CBC and coags if patient reasonably expected not to have any abnormalities (verbal communication with Dr. Durcan).
Prospective cohort 301 patients • Risk factors for CT head abnormality • >60 yo • Immunocompromised • Hx of CNS disease • Hx of seizure within 1 wk • Abnormal neurologic exam • Including poor comprehension • Sensitivity 94% • Specificity 51% HasbunR et al. Computed Tomography of the head before lumbar puncture in adults with suspected meningitis. NEJM 2001;345:1727-33.
What else do you need? • The obvious • Xylocaine • 1% or 2% • With or without epi • Topical disinfectant • 5% chlorhexidine (avoid detergent and 0.5% solution) • Proviodine solution • The essential • Sterile gloves • Face mask • The helpful • Piquet • Keep your RN happy • 2 Pillows
CSF tubes • How many tubes do you need? • How much CSF in each tube? • 1 cc • For most standard tests • 2 cc • HSV PCR • OCB (don’t forget to send serum!) • 3 cc • Cytology • 8 cc • AFB cultures • Fungal cultures
Local anesthesia • Max xylocainedose (70 kg individual) • 30cc if 1% • 15cc if 2% • s/c needle alone vs additional 20 gauge needle • The “bleb”
2. The Procedure Positioning Vertebral level
Positioning • Back as close to edge of bed as possible • Maximize anteroflexion • Minimize lateroflexion • Pillow under head & between legs • Be careful of the shoulders • Palpate along the vertebral bodies
Vertebral level • L3-L4 vs L4-L5 • Compromise between width of the space and spondylosis • Conusmedullaris extends to L2-L3 in 6% of pts
The Procedure • Aim towards the umbilicus • The expected resistance of the interspinousligament • The satisfying “pop” of the ligamentumflavum
The stylet • Never move the needle without the stylet! • With insertion of the needle • Avoid introduction of a plug of epidermis into the subarachnoid space, allowing for the growth of an epidermoid tumour • With removal of the needle • Prevent a strand of arachnoid being threaded into the dural defect, increasing risk of PLPHA
If not in the proper space • Most often needle is deviated from the midline • Hence the radicular pain • Attempt with large gauge needle (18 or 20 gauge) • If no CSF • Rotate the needle 90° • Advance further or withdraw • If slow flow • Valsalvamanoeuvres • Throw out any bloody needle
Negative pressure LP • Has been studied and found to be safe • Only while using 25 gauge needles or smaller! Linker G et al. Fine-needle, negative-pressure lumbar puncture: a safe technique for collecting CSF. Neurology 2002;59:2008–2009.
3. Interpreting the Results Normal values Tubes 1 & 4 Correcting for a traumatic tap
Normal CSF values • ≤ 5 RBC / μL • ≤ 5 WBC / μL • Protein • ≤ 0.5 gr/L • Cytology • 80% sensitive for leptomeningeal carcinomatosis from lymphoma or leukemia.
123 patients with suspected SAH • 8 patients with ruptured aneurysm on CA but negative CT head • 2 patients had a > 25% in RBC count between tubes #1 and #4
Correcting WBC in a traumatic tap • RBC x (peripheral blood WBC count ÷ peripheral blood RBC count) • Usually ~ 1000
Correcting protein in a traumatic tap • Add 0.01 gr/L for every 1000 RBC / μL
4. PLPHA Proven methods to decrease risk Unproven methods Treatment
PLPHA prevention • Proven methods • Bevel parallel to spine • Atraumatic needle • Needle gauge • Unproven • Recumbency • Volume of CSF removed
Systematic review of the literature • Atraumatic needle superior to Quincke • 24% versus 12% • Small gauge superior to large gauge
Needle types } “atraumatic” needles
Prospective cohort 239 patients • Sex • Women = 46%; men = 21% • Gauge • 20 gauge = 50%; 22 gauge = 26% VilmingST et al. The importance of sex, age, needle size, height and body mass index in post-lumbar puncture headache. Cephalalgia2001;21:738–743.
Bevel orientation • Prospective cohort of 380 patients • Bevel parallel to spine (bevel up) • 7.9% with PLPHA • Bevel perpendicular to spine • 19.3% with PLPHA Kochanowicz J et al. Post lumbar puncture syndrome and the manner of needle insertion [in Polish]. NeurolNeurochir Pol 1999;32(suppl 6):179–182.
Post LP recumbency has been studied by several studies, none of which have shown any clear benefit (up to 24 hrs) • Most clinicians will generally enforce some period • Dr. Bray’s 45 minutes
Epidural blood patch • 15-20 cc autologous blood • At site of LP • Supine 1-2 hrs post • 95% reported success rate
Summary • Preparation • Don’t hold the ASA • CBC, coags and neuro-imaging? • Plan your CSF tubes • The Procedure • Positioning! • The stylet • Interpreting the Results • Be concientious about Tubes 1 & 4 • Correcting for a traumatic tap • PLPHA • Prevention • Bevel parallel to spine • Atraumatic needle • Needle gauge • Treatment