A ventricular puncture is a form of lumbar puncture where the insertion point is made higher up the spine than usual. It is a very rare procedure and is usually only considered when a regular lumbar puncture may result in brain herniation. It poses a higher risk of spinal cord damage and resulting paralysis.
In Distractions the team had to perform a ventricular puncture on Adam because the lack of skin at the usual entry point on the spinal column posed too high a risk of infection of the cerebro-spinal fluid.