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Neurology > Technique of Lumbar Puncture > Flashcards

Technique of Lumbar Puncture Flashcards

1
Q

Disadvantage of seated position

A

Opening pressure readings may not be accurate

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1
Q

PMNs in CSF

A

Usually absent

may be found in centrifuged specimen

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2
Q

Effective strategies for reducing post LP headache

A

Use of small-diameter needle (22-gauge or smaller)

Use of atraumatic needle (Sprotte and others)

Replacement of stylet prior to removal of needle

Insertion of needle with bevel oriented in a cephalad to caudad direction (when using standard needle)

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3
Q

How to differentiate bloody tap from SAH

A

centrifuged sample’s supernatant

clear- bloody tap

xanthochromia-SAH

Bloody tap clears spontaneously

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3
Q

Onset of post LP headache

A

48 hrs but may be delayed upto 12 days

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3
Q

Mechanism of action of epidural blood patch

A

sealing off a dural hole with blood clot

compression of the CSF space by the clot, increasing CSF pressure

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4
Q

Positioning for LP in seated attitude

A

foot resting on chair

curl forward trying to touch umbilicus with nose

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4
Q

When should one completely withdraw needle and reposition

A

second hit against bone

Ask the patient to straighten back before repositioning

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4
Q

Strategies not effective in reducing post LP headache

A

Bed rest (up to 4 h) following LP

Supplemental fluids

Minimizing the volume of spinal fluid removed

Immediate mobilization following LP

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4
Q

Normal total CSF protein

A

15–50 mg/dL

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5
Q

Associated symptoms with post LP headache

A

nausea

neck stiffness

blurred vision

photophobia

tinnitus

vertigo

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6
Q

Location of postLP headache

A

occipitofrontal

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7
Q

Aggravating and relieving factors for post LP headache

A

Aggravating: sitting,standing

relieving factors: reclining,abdominal compression

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7
Q

Normal CSF glucose

A

40–70 mg/dL

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7
Q

Normal CSF volume

A

150ml

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9
Q

INR and platelet counts at which bleeding complications rarely occur

A

platelet count>50,000

INR

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11
Q

LMWH should be stopped _______ hrs before LP

A

24

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12
Q

Complications of LP

A

Cerebral herniation

Injury to spinal cord,nerve roots

hemorrhage

infection

back ache

Post dural puncture headache

radicular pain or numbness

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13
Q

LP should be delayed for ________ min after injection of anesthetic

A

10-15min

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14
Q

Supportive care for post LP headache

A

trendelenberg position

analgesics

antiemetics

caffeine

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15
Q

How much of CSF can be safely removed

A

20-30 ml

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15
Q

Cells normally absent in CSF

A

No RBCs

No PMNs

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15
Q

Normal CSF ammonia

A

25–80 µg/dL

15
Q

Normal CSF pressure

A

50–180 mmH2O

17
Q

Vertebral level at which spinal cord ends

A

L1 in 94%

L2-L3 interspace in remaining 6%

17
Q

Characteristic of Post LP headache

A

dull ache or throbbing

19
Q

Upper limit of normal opening pressure in supine patients

A

180mm H2O

May be as high as 200-250 in obese adults

20
Q

Normal CSF lactate

A

10–20 mg/dL

21
Q

Platelet count less than _________ is a contraindication to LP

A

20,000

22
Q

Increased risk of post LP headache

A

younger age

female gender

23
Q

Anxiety alleviation before LP

A

Lorazepam 1-2mg PO 30 min prior to procedure

or IV 5min before

24
Q

Normal CSF differential

A

Lymphocytes 60–70%
Monocytes 30–50%
Neutrophils None

26
Q

Does lying recumbent for 1h after LP decrease headache

A

no

27
Q

patients at risk of herniation following LP

A

altered level of consciousness

a focal neurologic deficit

new-onset seizure

papilledema

an immunocompromised state

29
Q

Next step if no fluid is seen after apparently correct placement

A

rotate the needle 90-180 degrees

If still no fluid is seen,advance needle with stylet slightly

30
Q

Tests to be performed if a bleeding disorder is suspected

A

platelet count

INR

aPTT

32
Q

Local anesthesia in LP

A

1% lidocaine 3-5ml

33
Q

Side effect of IV caffeine

A

atrial fibrillation

35
Q

Removal of LP needle

A

Insert the stylet before removing

36
Q

studies performed on CSF samples

A

(1) cell count with differential
(2) protein and glucose concentrations
(3) culture (bacterial, fungal, mycobacterial, viral)
(4) smears (e.g., Gram’s and acid-fast stained smears)
(5) antigen tests (e.g., latex agglutination)
(6) polymerase chain reaction (PCR) amplification of DNA or RNA of microorganisms (e.g., herpes simplex virus, enteroviruses)
(7) antibody levels against microorganisms
(8) immunoelectrophoresis for determination of -globulin level and oligoclonal banding
(9) cytology

38
Q

In adults,needle is advanced _______ cm before SAS is reached

A

4-5cm

39
Q

Normal CSF IgG

A

0.9–5.7 mg/dL

40
Q

post LP headache occurs in _______ % of pts

A

10-30%

41
Q
A

Quincke needle(traumatic)

43
Q

When should one partially withdraw needle and reinsert at different angle

A

needle hits bone

sharp radiating pain down one leg

if no fluid appears (“dry tap”)

44
Q

Rx of pts with persistent pain

A

IV caffeine 500 mg in 500 mL saline administered over 2 h

Epidural blood patch(15ml of autologous whole blood)

45
Q

Normal CSF albumin

A

6.6–44.2 mg/dL

46
Q

Normal WBC count

A

< five mononuclear cells (lymphocytes and monocytes) per µL

48
Q

complications of LP in pts on anticoagulants or pts with coagulation defects

A

subdural or epidural hematomas

49
Q

Topical anesthesia for LP

A

Lidocaine 4% cream applied 30 min before procedure

lidocaine/prilocaine must be applied 60-120min prior

50
Q

causes of xanthochromia

A

SAH

liver disease

elevated CSF protein >150-200mg/dl

52
Q

When should spinal imaging precede LP

A

symptoms suggestive of cord compression

back pain

leg weakness

urinary retention or incontinence

53
Q

positioning for LP

A

edge of bed

roll up into ball

pelvis and shoulder should be vertically aligned without any tilt

54
Q

OGB(oligoclonal bands)

A
55
Q

duration of post LP headache

A

subsides within a week

minority can persist for weeks or months

56
Q

The latency of subsidy of headache is __________ proportional to duration of standing

A

directly

57
Q
A

sprotte needle( atraumatic)

Neurology (2 decks)

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