Lumbar puncture Flashcards
What connects the spinous processes?
Supraspinal ligaments
_______ _______ is an elastic membrane covering the intralaminar space in which you must go through.
Ligamentum flavum
______ _________ is composed of tough, fibrous, and elastic tissue
Outermost covering membrane of spinal canal
Dura mater/dural sac
________ ________ is delicate, avascular membrane, Lines dural sac Encloses CSF filled subarachnoid space containing spinal cord and nerves.
Arachnoid mater
Lumbar punctures are performed at what anatomic landmarks?
L3-L4 or L4-L5
Angle the needle towards what ?
The umbilicus
What to do if you hit bone :
Remove needle and try again this time more downward (caudally).
If there are many neutrophils in the CSF analysis, the infection is most likely
Bacterial
If there are many lymphocytes in the CSF then this could indicate :
VIRAL aseptic meningitis
Normal RBC count in CSF analysis :
<10
Traumatic Tap is ruled out by the appearance of :
Xanthochromia
Normal glucose in CSF analysis :
50-80 mg/dL
CSF glucose might be low in which conditions ?
Bacterial meningitis
Sarcoidosis
Syphilis
Subarachnoid hemorrhage
Glucose levels are variable in :
Viral causes
SERUM hyperglycemia may be masking what ?
It may be masking low CSF glucose. Check serum as well.
Normal protein CSF? What if it’s elevated?
15-45 mg/dL. Elevated could mean infection from either bacterial or viral origin.
Gram stain showing gram negative diplococci :
N. Meningitides
Gram negative bacilli:
H. flu
Gram positive cocci:
Step pneumoniae, strep, or staph
How long do cultures take ?
24-48 hours
__________ is a yellow / orange discoloration of CSF fluid, is a product of RBC lysis, and is a a result of subarachnoid hemorrhage.
Xanthochromia
What is the normal opening pressure in LP?
18-20 mmH2O
Bacterial infection if opening pressure is what?
> 30
How to get opening pressure ?
Patient laying on side with the stop cock valve pointing up.
This position is called what ?
Lateral recumbent position
Clinical findings associated with pseudotumor cerebri ( intercranial hypertension) :
Headache, papilledema, diplopia, blurry vision.
Diagnostic indications for LP:
CNS infection (meningitis), inflammatory processes, suspected spontaneous subarachnoid hemorrhage, unexplained seizure, malignancy
Therapeutic indications for LP:
relieve intracranial pressure, deliver medication
Indications for emergent CT before LP:
To rule out head bleed and meningitis. (Important not to delay antibiotics )
What are the absolute contraindications for LP?
local skin infection, intracranial/spinal cord lesion, raised ICP w impending herniation, uncontrolled bleeding, Coumadin
What are the relative contraindications for LP?
raised ICP, spinal cord deformity, body deformity, suspected lumbar epidural abscess, thrombocytopenia, elevated INR
How many tubes are used to collect fluid ?
Four
What is tube 1
Cell count, differential
What is tube 2?
Glucose, protein
What is tube 3?
Culture, gram stain.
What is tube 4
Also cell count , differential
Approximately how much fluid is collected?
4-8ml
If RBC is higher in tube 4 than tube 1 this might indicate what ?
Traumatic tap
The line connecting posterior iliac crests will intersect midline at approximately ____.
L4
