A lumbar–peritoneal shunt is a technique to channelise the cerebrospinal fluid (CSF) from the lumbar thecal sac into the peritoneal cavity.
[1] A shunt is described as a tube, catheter or "surgically created anastomosis"[2] and is designed to bypass or redirect bodily fluids from one point in the body to another.
The subarachnoid space is a spongy tissue-filled cavity that surrounds the brain and spinal cord, where cerebrospinal fluid (CSF) is contained.
Once in place the lumbar–peritoneal shunt is used to drain the excess cerebrospinal fluid from the brain via the subarachnoid space and transport it to the peritoneal cavity, where it is eventually absorbed by the organs and passed out of the body during urination.
The operation is performed under general anesthetic by a neurosurgeon and usually takes a couple of hours.