Lumbar puncture

Question 1

List 3 indications for lumbar puncture

Answer 1

Suspected CSF/CNS infection, Check CSF composition and colour, diagnose guillain-barree (high protein content) and MS (oligoclonal bands)

Question 2

List 7 contraindications to lumbar puncture

Answer 2

Patient refusal, Intracranial bleed, Raised ICP, Infection over region for lumbar puncture, Coagulopathy, cord compression, malformation

Question 3

How would a patient with uncal herniation present?

Answer 3

headache, nausea vomitting, hypertension and bradycardia

Question 4

How would a patient with cerebellar herniation present

Answer 4

loss of reflexes, seizure and hypertension

Question 5

How would a patient with raised ICP present?

Answer 5

Nausea, vommitting, confusion/change in behaviour, papilloedema, CN III and IV palsy

Question 6

List 5 complications of lumbar puncture

Answer 6

Headache (cuased by pulling on meninges and high innervation by trigeminal nerve), bloody traumatic tap, brain or cerebellar herniation, meningitis

Question 7

Name 3 ligaments punctured during lumbar puncture

Answer 7

Supraspinatus, Interspinatus, Ligamentum flavum

Question 8

Where does the spinal cord terminate?

Answer 8

L1-L2

Question 9

How many and what are the pops in a)Lumbar puncture and b) Epidural ?

Answer 9

Lumbar puncture: 2 pops, ligamentum flavum –> dura mater and arachnoid mater
Epidural: 1 pop, ligamentum flavum

Question 10

Where does the subarachnoid space terminate? How is it landmarked?

Answer 10

S2 landmarked by the PSIS and the sacral spinous process

Question 11

Which structure is pierced causing bleeding in a traumatic tap? Where does this structure sit relative to spinous process?

Answer 11

Internal vertebral plexus - sits lateral, therefore deflection of the needle could cause trauma

Question 12

What does the cauda equina supply?

Answer 12

motor function to hips, knees, ankles, feet, internal and external anal sphincter

Question 13

Where is an adult LP performed (landmark)?

Answer 13

L3/L4 or L4/L5 -palpate the supracristal plane to identify L4 and go 1 spinous process level below to account for variability of spinal cord termination

Question 14

Where is an LP performed in children? Why?

Answer 14

L4/L5 or S1/S2- their spinal cord terminates lower down due to their size

Question 15

Why is the orientation of the bevel of needle important?

Answer 15

Bevel should be facing the ceiling with the patient lying on their side - aligns with the direction of the fibres making the dura so the fibres are split not cut; helps with healing, headache and leaking of fluid

Question 16

How should a patient be positioned?

Answer 16

Lying or sitting with their knees in their chest to maximise space between vertebra.

Question 17

Why do patients need to wear a sats probe when doing an LP

Answer 17

The position of flexed back could cause breathing problems as the chest cannot expand properly

Question 18

What are 2 indications for epidural anaesthesia?

Answer 18

Childbirth and lower limb surgery

Question 19

Where can epidurals be done?

Answer 19

anywhere along the length of the spinal cord however lumbar region has lowest risk of hitting the spinal cord

Question 20

why should care with epidurals be taken?

Answer 20

Too much or wrong position inserting anaesthesia can cause paralysis of the diaphragm and cardiac dysfunction

Question 21

Why does the angle of the needle have to become less angulated as you descend down the column?

Answer 21

The vertebral column angulation changes as you descend

Question 22

Where are spinal anaesthesias performed?

Answer 22

L3/L4 to L5-S1

Question 23

How is the level of anaesthesia controlled in a spinal block?

Answer 23

The tissues are bathed in anaesthetic, the level of anaesthesia is controlled by the density of the anaesthetic compared to the density of the CSF (anaesthetic is more dense so will sink to the bottom meaning more is needed for higher up blocks)

Question 24

Can both an epidural and spinal block be done?

Answer 24

Yes, first advance needle into epidural space deliver anaesthetic and then into the subarachnoid space and deliver anaesthetic there

Question 25

Where is a caudal epidural delivered and how do you landmark it?

Answer 25

Sacral hiatus- equilateral triangle drawn between PSIS; the bottom of the triangle will be the hiatus

Question 26

When is a caudal anaesthesia done?

Answer 26

Childbirth and to numb the perineum

Question 27

What can cause a dry tap?

Answer 27

Needle travelling off course or the patient not flexing enough