LUMBAR PUNCTURE COURSE - cont'd info

Indications for a diagnostic lumbar puncture

Diagnostic lumbar puncture-urgent

• Suspected meningitis
• Suspected early subarachnoid hemorrhage in
  patients with negative CT scan

– RBC in CNS can mean a traumatic tap, but expect the RBC to clear
from tubes 1-4

– Xanthrochromia (pink or yellow tint) represents hemoglobin
breakdown after two hours.

– Elevated opening pressure

– Exceedingly rare if third-generation head CT scan negative

Diagnostic lumbar puncture-nonurgent

– Suspected meningeal carcinomatosis
– Pseudotumor cerebri
– Tuberculous meningitis
– CNS syphillis
– CNS vasculitis (very rare)

Adjunctive information for diagnosis

– Multiple sclerosis
– Guillain Barre syndrome
– Transverse myelitis

Indications for a therapeutic lumbar puncture

Therapeutic Lumbar Puncture

• Treatment of pseudotumor cerebri
  > Removal of 25-35 mL CSF
• Intrathecal injection of antimicrobials or chemotherapy
• Spinal anesthesia
• Injection of contrast media for myelography
• Adjunctive therapy for cryptococcal meningitis

Contraindications for a lumbar puncture

– Now use Platelets <50,000
– Active anticoagulation or recent receipt of antithrombotics or thienopyridines

• • Infection at insertion site
  • Elevated intracranial pressure
    – AMS (LR 2.2); Focal deficit (LR 4.3); Papilledema (LR 11)
  • Supratentorial mass lesion with mass effect
  • Posterior fossa mass
  • Obstructive hydrocephalus
  • Arnold-Chiari malformation
  • Thrombocytopenia
    – PLT<40,000

• Coagulopathy
  – INR > 1.5 (warfarin) or ≥1.8 (cirrhosis)
  PTT > 1.5 x upper limit of normal
• Uncooperative patient

• Midline shift
• Loss of suprachiasmatic and basilar cisterns
• Posterior fossa mass
• Loss of superior cerebellar cistern
• Loss of quadrigeminal plate cistern
  

Complications of a lumbar puncture

• Epidural hematoma
• Epidural abscess
• Diskitis
• Brain herniation (if elevated intracranial pressure
  present)
• Seizure
• CSF leak
  

• Spinal headache (4-20%)
• Minimized with needle < 22 gauge
• Quincke bevel parallel to
  longitudinal axis of spine
• Risk decreased 5-6 x with
  pencil tip (Sprotte or
  Whitacre or Gertie Marx) vs
  bevel tip (Quincke) needle
• Local back pain
• Lower extremity paresthesias
  

Equipment for a lumbar puncture

• 5 mL syringe
• 25 gauge needle
• 1% lidocaine
• Manometer
• Sterile vials
• Scrub brushes
• Betadine
• Drapes
• Spinal needles

22 gu 3.5 inch, adults
22 gu, 2.5 inch, children
22 gu, 1.5 inch, infants

When to get a CT scan of the head prior to a lumbar puncture

Clinical risk factors for increased ICP

– AMS (LR 2.2)
– Focal deficit (LR 4.3)
– Papilledema (LR 11)

– Age≥60
– Immunocompromised state
– Seizure in last week
– Abnormal level of consciousness
– Inability to answer 2 questions correctly
– Inability to follow 2 consecutive commands correctly
– Gaze palsy
– Abnormal visual fields
– Facial palsy
– Arm (or pronator) drift
– Leg weakness
– Abnormal speech or language

Proper positioning and technique for a lumbar puncture

• Systematic review and meta-analysis
• 14 RCT of ultrasound-guided LP vs landmark-guided LP
• Investigated 1334 patients

Results:

– Lower failure rate (1% vs 7.2%, p<0.001))

• • 85% reduction in failed attempts

– Reduced risk of traumatic LPs

• • Risk ratio 0.27 (CI 0.11-0.67, p =0.005)

– Reduced number of insertion attempts

• • Decreased by 0.5 attempts

– Decreased number of needle redirections

• Decreased by 1 needle redirection

• Prospective, randomized study
• 43 infants <60 days old
• Ultrasound-assisted LP 100% successful
• Landmark-guided LP – 82% successful
  – OR = 9.33 for successful LP with ultrasound-assistance

Cerebrospinal fluid analysis

Routine studies

– Cell count with differential
– Culture and gram stain
– Glucose and protein

Optional studies depending on clinical suspicion

– Infectious studies: VDRL, cocci titer, AFB RNA by PCR, encephalitis
panel, India ink, cryptococcal antigen, adenosine deaminase level
(for Tb), lactate level, HSV RNA by PCR, VZV RNA by PCR

– Multiple sclerosis: Oligoclonal bands, IgG index, myelin basic
protein

– Cytology

– ACE level

Coding for a lumbar puncture

• 62270 Spinal puncture, lumbar, diagnostic
• 62272 Spinal puncture, therapeutic, for drainage of spinal fluid