Next the ER doctor performed the spinal puncture.

Nissl was possibly the greatest neuropathologist of his day and also a fine clinician who popularised the use of spinal puncture, which had been introduced by Heinrich Quincke.

Cerebrospinal fluid analysis (through a lumbar spinal puncture) and electrodiagnostic tests of nerves and muscles (such as nerve conduction studies) are common tests ordered in the diagnosis of GBS.

They later tried infecting people with "direct inoculations made from syphilis bacteria poured into the men's penises and on forearms and faces that were slightly abraded ... or in a few cases through spinal punctures".

Dandy also observed that air introduced into the subarachnoid space via lumbar spinal puncture could enter the cerebral ventricles and also demonstrate the cerebrospinal fluid compartments around the base of the brain and over its surface.