Ommaya Reservoir

Nov. 14, 2025

This page was reviewed under our medical and editorial policy by Keng Lam, M.D., assistant clinical professor, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte.

An Ommaya reservoir is a device that is placed beneath a person’s scalp to allow doctors to deliver chemotherapy directly into a patient’s cerebrospinal fluid. This is the fluid produced in the brain that surrounds and protects both the brain and the spinal cord. It may be used to treat certain kinds of brain tumors. Ommaya reservoirs may also be used to take samples of cerebrospinal fluid for testing during treatment for cancer.

Another device used to help treat some brain tumors is a brain shunt. Although both devices are placed in the brain by a neurosurgeon, an Ommaya reservoir simply allows doctors access to the cerebrospinal fluid, while a brain shunt helps drain excess fluid away from the brain.

What Is an Ommaya Reservoir?

An Ommaya reservoir is a small, dome-shaped device that is placed beneath the scalp, usually near the top of the head. A small tube called a catheter is attached to the reservoir. During surgery, the other end of the catheter is placed into a ventricle – a cavity in the brain where cerebrospinal fluid is made. After the device is surgically placed, cancer doctors can deliver chemotherapy to the brain through the Ommaya reservoir.

An Ommaya reservoir is sometimes referred to as an Ommaya shunt or an Ommaya port.

Ommaya Tap

The term Ommaya tap refers to the process of inserting a needle into a patient’s Ommaya reservoir. This may be done to remove a sample of cerebrospinal fluid for testing or to deliver chemotherapy into the reservoir so that it can travel to the cerebrospinal fluid and circulate around the brain.

Ommaya Reservoir Chemotherapy

Ommaya reservoir chemotherapy is a type of intrathecal chemotherapy – the term for any chemotherapy that is delivered directly to the cerebrospinal fluid. Although it’s not used as often as some other treatment options, Ommaya reservoir chemotherapy may be recommended for certain patients or cancer types, including:

• Patients with certain types of leukemia or lymphoma that are more likely to affect the central nervous system
• Patients with tumor cells that have spread to the spinal fluid

The benefit to using an Ommaya reservoir to deliver chemotherapy is that the medication can be sent directly to the cerebrospinal fluid, making it work more quickly and more effectively.

Ommaya Placement

An Ommaya reservoir is placed by expert neurosurgeons during a short surgical procedure.

• After making an incision in the skin of the scalp, surgeons drill a small hole in the skull.
• The catheter attached to the reservoir is guided through this hole to a part of the brain called a ventricle, where cerebrospinal fluid is produced.
• The dome-shaped reservoir is then placed between the skin and the skull and the incision is closed.
• Shortly after the procedure, doctors will use imaging like computed tomography to check that the reservoir is placed correctly.

In most cases, an Ommaya reservoir is not removed after it is placed. Patients with an Ommaya reservoir do not usually feel much pain or discomfort after it is implanted and the device does not require any maintenance.

Side Effects

Most people with an Ommaya reservoir don’t experience any long-term side effects. However, there are some potential risks related to the surgical placement of the device, including bleeding or infection at the site of the wound or in the brain. Thankfully, these issues are very rare.

Ommaya Reservoir Success Rate

The success rate for surgically placing an Ommaya reservoir is very high, meaning that almost no patients experience serious side effects or issues related to implanting the device. Multiple studies have also shown that Ommaya reservoirs are a valuable tool in treating certain kinds of late-stage brain tumors, which may help increase survival for certain patients.