It consists of a catheter in one lateral ventricle attached to a reservoir implanted under the scalp.

It is used to treat brain tumors, leukemia/lymphoma or leptomeningeal disease by intrathecal drug administration.

In the palliative care of terminal cancer, an Ommaya reservoir can be inserted for intracerebroventricular injection (ICV) of morphine.

[1] It was originally invented in 1963 by Ayub K. Ommaya, a Pakistani-American neurosurgeon.

In January 2017, researchers at University of Texas Southwestern Medical Centre used an Ommaya reservoir to measure the intracranial pressure that is regularly observed in astronauts in zero-gravity conditions.