Lumbar Puncture Flashcards
Define a lumbar puncture?
procedure in which needle is inserted into spinal canal to collect sample of CSF for diagnostic testing
-> CSF sent for micrcopsy for
Where is the needle inserted for an LP in an adult and in children ?
Adults= L4/L3
Children= L4/L5
Describe the passage of the needle in an LP?
The needle enters skin, subcutis, supraspinous ligament, interspinous ligament, ligamentum flavum (first give), epidural space, dura mater (second give) then subarachnoid membrane to enter subarachnoid space.
What is looked for in the CSF?
CSF is sent for microscopy, culture, protein, glucose and lactate
what are the indications for an LP?
Diagnostic to look for:
- Oligoclonal bands – MS
- High protein – Guillan Barre syndrome
- Blood or bilirubin – SAH
- Pathogens – bacterial meningitis, viral encephalitis
- Malignant cells – CNS lymphoma
- Rapid improvement in gait and cognitive function after removal of 30L of CSF – normal pressure hydrocephalus
Therapeutic
- Intrathecal drug administration
- Temporary reduction in ICP – idiopathic intracranial hypertension
what is the appearance, WCC, protein, glucose of CSF in a bacterial infection
what is the appearance, WCC, protein, glucose of CSF in a viral infection ?
what is the appearance, WCC, protein, glucose of CSF in a TB infection?
what is the appearance, WCC, protein, glucose of CSF in SAH?
what is the appearance, WCC, protein, glucose of CSF in GB?
What are the possible complications of LP?
Post-dural puncture headache – due to intracranial hypotension
Nerve root pain – due to irritation
Infection
Bleeding
Cerebral herniation
Minor/transient neurological symptoms e.g. paraesthesia
Any changes in lower body neurology after an LP should be treated as cauda equina compression (haematoma/abscess)
What are the contraindications for an LP?
raised ICP! -> Causes coning (tonsillar herniation) through Foramen Magnum
Increased bleeding tendency, infection at site, cardiorespiratory compromis
