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NEURO > Lumbar puncture > Flashcards

Lumbar puncture Flashcards

1
Q

what are the indictions for lumbar puncture

A

To obtain CSF for the diagnosis of:

Meningitis

Meningoencephalitis

Subarachnoid haemorrhage

Malignancy – diagnosis and treatment

Idiopathic Intracranial Hypertension

Other neurologic syndromes

Infusion of Drugs or contrast

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2
Q

what are the contraindication for lumbar puncture

A

unstable patient
- cardiovascular or respiratory

localised skin/soft tissue infection over puncture site

evidence of unstable bleeding disorder
- low platelets or clotting factor deficient

increased ICP

high complete subarachnoid spinal block - if LP down below the level of block can cause neurological deterioration

chiari malformations - structural defects of the cerebellum

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3
Q

what investigations can be done to determine if there is raised ICP before LP

A

fundoscopy - papilloedema, retinal haemorrhage

CT head - rule out impending cerebral mass herniation that could increase ICP

**normal CT does not rule out ICP

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4
Q

what equipment is used for lumbar puncture

A

anaesthetics

  • topical
  • lidocaine with 25 1% gauge needle and syringe

povidone-iodine solution and sponge wand

drapes, gauzes, bandages

manometer, stopcock valv, tubing

spinal needle - usually 22 gauge
OR
atraumatic needle

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5
Q

what is the benefit of using atraumatic needles

A

cause less spinal headaches

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6
Q

what are the different lengths of needles used in LP

A
  1. 5 inch for <1 yr
  2. 5 inch for 1yr- middle childhood
  3. 5 inch for older children and adolescents

larger for adults and large adolescents

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7
Q

what are the pre procedural steps for LP

A

Apply topical anesthetic 30-45 min prior to procedure

Spinal cord usually ends at L1-L2(check!), so sites for puncture are located at L3-L4 or L4-L5

Restrain patient in lateral decubitus position

  • Maximally flex spine without compromising airway
  • Keep alignment of feet, knees and hips
  • Position head to left if right handed or vice versa
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8
Q

what is the procedure for LP insertion

A

cleanse skin around puncture site and allow to dry

anaesthetise with lidocaine if topical not used

insert spinal needle with stylet with bevel up to

aim towards umbilicus - directing needle slightly towards the head

remove stylet and check for flow of spinal fluid

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9
Q

what should be done if there is no fluid after the removal of the stylet

A

rotate needle 90 degrees

reinsert stylet and advance needle slowly checking frequently for CSF

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10
Q

what can increase CSF pressure in low flow situations

A

jugular vein compression

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11
Q

what does bony resistance felt immediately indicate

A

you are not in the spinal interspace

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12
Q

what should you do is deep bony resistance felt

A

withdrawal of needle to skin surface and redirect more towards the head

increase patient flexion

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13
Q

what should you do if bloody fluid that does not clear or that clots results

A

withdraw needle and reattempt at a different interspace

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14
Q

what does a pop of sudden decrease in resistance indicate

A

ligamentum flavum and dura punctured

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15
Q

what should be done if normal CSF is flowing

A

attach manometer and read column when highest level achieved

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16
Q

how much CSF should be collected

A

1ml of CSG in each of 3 vials

tube 1 - culture and gram stain

tube 2 - glucose and protein

tube 3 - cell count and differential

**extra CSF if desired for other lab tests

17
Q

what should be done on finishing the LP

A

check closing pressure

reinsert stylet and remove needle in one quick motion

cleanse and cover puncture site

18
Q

why might a sitting position be used for LP

A

infants

19
Q

how is a LP done in a sitting position

A

Restrain infant in the seated position with maximal spinal flexion

Hold infant’s hands between flexed legs with one hand and flex head with the other hand

Insert needle so bevel is parallel to spinal cord (Bevel left or right)

20
Q

what cannot be measured accurately in the sitting position

A

pressure

21
Q

when is a paramedian/lateral approach used in LP

A

patient who have calcifications from repeated LPs or anatomical abnormalities

needle passes through erector spinal and ligamentum flavum

22
Q

what is there less incidence of in paramedian LP and why

A

spinal headache

- less because the holes through the dura and arachnoid tissues do not overlap

23
Q

what are the complications of LP

A

headache - most common

apnea (central or opstructive)

back pain - sometimes disc herniation

bleeding or fluid leak around spinal cord

infection, pain, haematoma

subarachnoid epidermal cyst

ocualr nerve palsy

nerve trauma

brainstem herniation

24
Q

what are risk factors for spinal headache

A

female
18-30
lower BMI

25
Q

how long can spinal headache last and what is the management

A

can last hours to weeks

supine position for at least 2 hours
hydration
caffeine - PO or IV
epidural blood patch

26
Q

how can spinal headache be prevented

A

passing needle bevel parallel to longitudinal fibres of dura

replacing stylet before removing needle

using smaller diameter needles

using atraumatic needles

27
Q

what can be felt in nerve root trauma/irritation

A

electric shocks
dysesthesias

back pain

28
Q

what should be done if there is nerve root trauma/irritation

A

remove needle immediately

if pain/motor weakness persists start corticosteroids

EMG if pain persists

29
Q

how does herniation present

A

initially altered mental status

cranial nerve abnormalities

cushings triad

  • irregular respirations
  • bradycardia
  • sistolic hyeprtension
30
Q

how are herniations managed

A

can be rapidly fatal

immediately remove needle

raise head of bed to 30-45 degrees to improve venus return

mannitol or 3% saline

intubate patient anf hyperventilte

emergent neurosurgical consult

31
Q

how does an epidermal inclusion cyst occur

A

due to use of stylet

when core of skin is driven into spinal or paraspinal space with hollow needle

avoid - do not remove stylet until through the skin

32
Q

what can be done if the procedure fails

A

have someone else try

bedside ultrasound

radiographic guided procedure - fluoroscopy, US, CT

cisterna magna tap

33
Q

what are some of the characteristics of CSF

A

clear and colourless

opening pressure - 6-16 mm/H2O

protein level 35mg%

glucose level 60mg% (60% of serum glucose) serum glucose

WCC <5

34
Q

what must be done when sending off CSF sample for Xanthochromia

A

put in a brown paper envelope to protect from light

35
Q

what must you pair with the CSF sample when looking for oligoclonal bands

A

send glucose sample

NEURO (51 decks)

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