Lumbar puncture

Question 1

Define:

Answer 1

A procedure where a needle is inserted into the spinal canal to collect CSF

In adults this is done at l3/4 but in children at l4/5

When needle enters will go through skin, subcutis, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space dura mater, subarachnoid membrane and subarachnoid space

Question 2

Contraindications:

Answer 2

Raised ICP (will cause herniation through the foramen magnum)
Infection at the site
Bleeding tendencies
Cardiorespiratory compromise

Question 3

Indications for diagnostic reasons:

Answer 3

Oligoclonal bands = MS
High protein = GBS
Blood or bilirubin = SAH 
Pathogens = meningitis or encephalitis 
Malignant cells = CNS lymphoma 
Rapid improvement of gait and confusion on removing 30L of CSF = normal pressure hydrocephalus

Question 4

Indications for therapeutic reasons:

Answer 4

Intrathecal injections

Temporary reduction in ICP (idopathic intracranial hypertension)

Question 5

Complications:

Answer 5

Infection

Bleeding

Cerebral herniation

Nerve root pain (due to irritation)

Post dural puncture headache (due to intracranial hypotension)

minor/transient neuro symptoms such as parasthesia

Any changes lower than LP should be treated as cauda equina due to abscess or haematoma