Lumbar PunctureWhat you need to know (and what I wish I had)

Mark Keezer, MDCM, FRCPCMSc 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

Outline1. Preparation2. The Procedure3. Interpreting the Results4. PLPHA

1. Preparationa. Consentb. Antiplateletsc. Labsd. Neuro-imaginge. Supplies needed

Patient consent• Back pain• Radicular pain• Hemorrhage• Infection

• PLPHA (~40%)

Should antiplatelets or prophylactic heparin be

held?

• Prospective cohorto 924 orthopedic patients undergoing spinal or epidural anesthesiao 39% receiving antiplateletso 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 centreo 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 abnormalityo >60 yoo Immunocompromisedo Hx of CNS diseaseo Hx of seizure within 1 wko 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 2001;345:1727-33.

The LP kit

What else do you need?

• The obviouso Xylocaine

• 1% or 2%• With or without epi

o Topical disinfectant• 5% chlorhexidine (avoid detergent and 0.5% solution)• Proviodine solution

• The essentialo Sterile gloveso Face mask

• The helpfulo Piquet

• Keep your RN happyo 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 Procedurea. Positioningb. Vertebral level

Positioning• Back as close to edge of bed

as possible

• Maximize anteroflexion

• Minimize lateroflexiono Pillow under head & between legso Be careful of the shoulderso 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 needleo Avoid introduction of a plug of epidermis into the subarachnoid space,

allowing for the growth of an epidermoid tumour

• With removal of the needleo Prevent a strand of arachnoid being threaded into the dural defect,

increasing risk of PLPHA

• If not in the proper spaceo Most often needle is deviated from the midline

• Hence the radicular paino Attempt with large gauge needle (18 or 20 gauge)

• If no CSFo Rotate the needle 90°o Advance further or withdraw

• If slow flowo 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. Normal valuesb. Tubes 1 & 4c. Correcting for a traumatic tap

Normal CSF values• ≤ 5 RBC / μL• ≤ 5 WBC / μL

• Proteino ≤ 0.5 gr/L

• Cytologyo 80% sensitive for leptomeningeal carcinomatosis from lymphoma or

leukemia.

• 123 patients with suspected SAHo 8 patients with ruptured aneurysm on CA but negative CT heado 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. PLPHAa. Proven methods to decrease riskb. Unproven methodsc. Treatment

What can we do to prevent PLPHA?

PLPHA prevention• Proven methods

o Bevel parallel to spineo Atraumatic needleo Needle gauge

• Unproveno Recumbencyo 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

• Sexo Women = 46%; men = 21%

• Gaugeo 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 posto 95% reported success rate

Summary1. Preparation

1. Don’t hold the ASA2. CBC, coags and neuro-imaging?3. Plan your CSF tubes

2. The Procedure1. Positioning!2. The stylet

3. Interpreting the Results1. Be concientious about Tubes 1 & 42. Correcting for a traumatic tap

4. PLPHAo Prevention

• Bevel parallel to spine• Atraumatic needle• Needle gauge

o Treatment

Questions?