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 http://www.nejm.org.proxy1.library.mcgill.ca/doi/full/10.1056/NEJMvcm054952 Outline 1. 2. 3. 4. Preparation The Procedure Interpreting the Results PLPHA 1. Preparation a. b. c. d. e. Consent Antiplatelets Labs Neuro-imaging Supplies needed Patient consent • • • • Back pain Radicular pain Hemorrhage Infection • PLPHA (~40%) Should antiplatelets or prophylactic heparin be held? • Prospective cohort o 924 orthopedic patients undergoing spinal or epidural anesthesia o 39% receiving antiplatelets o 2% receiving prophylactic heparin o 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. Anesth Analg 1995;80:303-9. • Risk of epidural hematoma with clopidogrel unknown What are the minimum platelet count and INR values? Coags & platelets • Platelets > 50,000 • INR <1.5 • Guidelines at the Preston Robb day centre o 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 o o o o o >60 yo Immunocompromised Hx of CNS disease Hx of seizure within 1 wk Abnormal neurologic exam • Including poor comprehension • Sensitivity 94% • Specificity 51% Hasbun R et al. Computed Tomography of the head before lumbar puncture in adults with suspected meningitis. NEJM The LP kit What else do you need? • The obvious o Xylocaine • 1% or 2% • With or without epi o Topical disinfectant • 5% chlorhexidine (avoid detergent and 0.5% solution) • Proviodine solution • The essential o Sterile gloves o Face mask • The helpful o Piquet • Keep your RN happy o 2 Pillows CSF tubes • How many tubes do you need? • How much CSF in each tube? o 1 cc • For most standard tests o 2 cc • HSV PCR • OCB (don’t forget to send serum!) o 3 cc • Cytology o 8 cc • AFB cultures • Fungal cultures Local anesthesia • Max xylocaine dose (70 kg individual) o 30cc if 1% o 15cc if 2% o s/c needle alone vs additional 20 gauge needle • The “bleb” 2. The Procedure a. b. Positioning Vertebral level Positioning • Back as close to edge of bed as possible • Maximize anteroflexion • Minimize lateroflexion o Pillow under head & between legs o Be careful of the shoulders o Palpate along the vertebral bodies Tuffier’s line Vertebral level • L3-L4 vs L4-L5 o Compromise between width of the space and spondylosis o Conus medullaris extends to L2-L3 in 6% of pts The Procedure • Aim towards the umbilicus • The expected resistance of the interspinous ligament • The satisfying “pop” of the ligamentum flavum The stylet • Never move the needle without the stylet! • With insertion of the needle o Avoid introduction of a plug of epidermis into the subarachnoid space, allowing for the growth of an epidermoid tumour • With removal of the needle o Prevent a strand of arachnoid being threaded into the dural defect, increasing risk of PLPHA • If not in the proper space o Most often needle is deviated from the midline • Hence the radicular pain o Attempt with large gauge needle (18 or 20 gauge) • If no CSF o Rotate the needle 90° o Advance further or withdraw • If slow flow o Valsalva manoeuvres • Throw out any bloody needle Negative pressure LP • Has been studied and found to be safe o 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 a. b. c. Normal values Tubes 1 & 4 Correcting for a traumatic tap Normal CSF values • ≤ 5 RBC / μL • ≤ 5 WBC / μL • Protein o ≤ 0.5 gr/L • Cytology o 80% sensitive for leptomeningeal carcinomatosis from lymphoma or leukemia. • 123 patients with suspected SAH o 8 patients with ruptured aneurysm on CA but negative CT head o 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) o Usually ~ 1000 Correcting protein in a traumatic tap • Add 0.01 gr/L for every 1000 RBC / μL 4. PLPHA a. b. c. Proven methods to decrease risk Unproven methods Treatment What can we do to prevent PLPHA? PLPHA prevention • Proven methods o Bevel parallel to spine o Atraumatic needle o Needle gauge • Unproven o Recumbency o Volume of CSF removed • Systematic review of the literature o Atraumatic needle superior to Quincke • 24% versus 12% o Small gauge superior to large gauge Needle types } “atraumatic” needles • Prospective cohort 239 patients • Sex o Women = 46%; men = 21% • Gauge o 20 gauge = 50%; 22 gauge = 26% Vilming ST et al. The importance of sex, age, needle size, height and body mass index in post-lumbar puncture headache. Cephalalgia 2001;21:738–743. Bevel orientation • Prospective cohort of 380 patients o Bevel parallel to spine (bevel up) • 7.9% with PLPHA o Bevel perpendicular to spine • 19.3% with PLPHA Kochanowicz J et al. Post lumbar puncture syndrome and the manner of needle insertion [in Polish]. Neurol Neurochir 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 o Dr. Bray’s 45 minutes Treatment of PLPHA Epidural blood patch • 15-20 cc autologous blood o At site of LP o Supine 1-2 hrs post o 95% reported success rate Summary 1. Preparation 1. 2. 3. 2. The Procedure 1. 2. 3. Positioning! The stylet Interpreting the Results 1. 2. 4. Don’t hold the ASA CBC, coags and neuro-imaging? Plan your CSF tubes Be concientious about Tubes 1 & 4 Correcting for a traumatic tap PLPHA o Prevention • Bevel parallel to spine • Atraumatic needle • Needle gauge o Treatment Questions?