Common Indications for Lumbar Puncture
The most common diagnostic indication for LP is suspicion of CNS
infections. Apart from that, CSF is essential for the diagnosis of
various neuro-inflammatory conditions viz Primary CNS
Vasculitis,3 autoimmune
encephalitis,4 acute transverse
myelitis,5 and Guillain-Barre
Syndrome.6 CSF study provides circumstantial evidence
in the diagnosis of Multiple Sclerosis and helps distinguish it from
other inflammatory demyelinating diseases like
NMO-MOG.7 CSF can be used to confirm the diagnosis of
subarachnoid haemorrhage, when the results of brain imaging are
inconclusive, by analysing degraded haemoglobin particles in
CSF.8 CSF cytology can identify suspected
leptomeningeal metastases, and CSF flowcytometry can corroborate in the
diagnosis of CNS.9 CSF opening pressure of
>25cm H2O is essential for the diagnosis of Idiopathic
Intracranial Hypertension.10 A normal opening pressure
and improvement in gait after removal of 30-50 ml CSF confirms the
diagnosis of Normal Pressure Hydrocephalus and predicts the efficacy of
CSF catheter placement.11
A lumbar puncture can be used therapeutically—e.g. intrathecal
colistin, vancomycin in ventriculitis,12 intrathecal
interferon in SSPE,13 intrathecal nusinersen in
SMA,14 intrathecal chemotherapy,15and intrathecal baclofen for spasticity.16Perioperative intrathecal fluorescein injection helps visualization of
CSF leaks at the skull base.17 Headache caused by
raised intracranial pressure in acute communicating hydrocephalus and
cryptococcal meningitis can be relieved by draining CSF by
LP18 and is associated with a 69% relative
improvement in survival.19 In patients with IIH, with
imminent visual loss, a lumbar puncture can be used as a rescue measure
to save vision before other definitive CSF diversion procedures can be
planned.20