Gamma Knife®


Northwell Health offers Gamma Knife Perfexion radiosurgery at the Center for Advanced Medicine in Lake Success on Long Island. The health system is one of only two locations on Long Island offering this treatment.

Gamma Knife radiosurgery is a stereotactic radiosurgery method that delivers high doses of radiation to a targeted area without damaging the surrounding healthy tissue. It can be used for both adults and children who have small to medium-sized brain tumors; blood vessel abnormalities such as arteriovenous malformations (AVMs); and such neurological conditions as trigeminal neuralgia, Parkinson’s disease, and epilepsy.  

Despite its name, Gamma Knife radiosurgery is a non-invasive, nonsurgical technique – there are no surgical incisions. The device uses beams of highly-focused gamma rays to treat small to medium size lesions, usually in the brain.

Because Gamma Knife radiosurgery does not cause injury to any tissues except those specifically targeted at the time of treatment, it is very effective in treating abnormalities in parts of the brain that are are too difficult to completely treat with an open surgical approach.

The procedure is done in an ambulatory outpatient setting. A lightweight frame is securely placed on the patient’s head and imaging of the brain is performed. This imaging can include MRI or CT. The images provide a map of the brain, which helps physicians determine the exact amount and precise location of radiation needed to target the abnormality. 

The patient is placed in the Gamma Knife, fully awake and able to communicate. During the half-hour treatment, 192 beams of radiation are aimed at the target. After the radiosurgery treatment is complete, patients are able to go home and resume their usual activities. 

In some cases, Gamma Knife radiosurgery is performed as a secondary treatment after open surgery to destroy abnormal tissue that may be too dangerous to remove during the surgical procedure. During the course of treatment with Gamma Knife, the care team may include the following specialty areas:

Conditions treated by Gamma Knife radiosurgery

Gamma Knife is used to treat malignant and benign tumors of the brain, as well as certain neurological conditions. Conditions that may be treated with a Gamma Knife procedure include, but are not limited to, the following:

Acoustic neuromas: These tumors are also known as vestibular schwannomas and most commonly develop on the nerves that are responsible for hearing and balance. Their unrelenting growth can cause deafness, facial weakness and facial numbness, as well as other neurologic deficits.  Gamma Knife radiosurgery can precisely target these tumors and stop their growth with a lower risk of deafness or loss of facial movement compared to conventional surgery. 

Arteriovenous malformations: Bleeding can occur from this type of abnormal blood vessel formation, and can cause severe headaches, seizures, or neurologic deficits (stroke).  Surgical removal of an AVM is curative, but some AVMs cannot be safely resected because of the risk of bleeding or injury to normal brain tissue.  Gamma Knife radiosurgery can eliminate the risk of bleeding from AVMS over a several months to several year time period by causing scar tissue to form in the abnormal blood vessels that shuts off blood flow. 

Brain metastasis:  Cancerous tumors in the lung, breast, or other parts of the body can spread to the brain, forming tumors called brain metastases. Brain metastasis treatment is the most common use of Gamma Knife radiosurgery and can be combined with surgery and whole brain radiation to optimally control these tumors.

Cavernous malformations:  These vascular malformations represent about 10 percent of all intracranial vascular malformations.  They consist of dilated vein capillaries and do not have any brain tissue within the malformation.  When they bleed, neurologic function may be lost (stroke).  Gamma Knife radiosurgery has been shown to be effective at decreasing the rate at which these malformations bleed, though it is generally recognized that surgical excision can completely remove the risk of further bleeding.  For cavernous malformations in parts of the brain where surgery is inadvisable and where bleeding may result in a loss of important brain function, Gamma Knife radiosurgery is a very low-risk choice with a proven track record.

Craniopharyngioma: Surgical resection can cure only some patients with craniopharyngiomas. These benign tumors develop at the base of the brain close to parts of the brain that are critical for vision, hormonal balance, and other very important normal structures that may make a complete surgical removal impossible.  In children, craniopharyngiomas are notorious for causing hormonal imbalances that result in short stature and learning difficulties. Gamma Knife radiosurgery can target craniopharyngioma tissue without damaging the surrounding normal brain tissues.

Epilepsy:  Medial temporal lobe epilepsy (MTLE) that has been unresponsive to medication therapy has typically been surgically treated with resection of the part of the brain where the seizures arise.  The ability of the Gamma Knife to treat parts of the brain that are not readily accessed surgically makes it an option for treating MTLE in some cases. 

Glial tumors: The majority of cells in the brain are glial cells, which have a vital role in supporting the function of nerve cells in the brain.  Glial tumors such as astrocytomas, oligodendrogliomas, ependymomas, mixed gliomas, glioblastoma, can development from glial cells and demonstrate a wide range of malignancy. The majority of glial tumors are difficult to control with surgery, radiotherapy, and chemotherapy.  Gamma Knife radiosurgery may be used to treat glial tumors, most often after standard therapies have been employed.

Hypothalamic hamartomas: These unusual tumors are located in the hypothalamus, close to the same areas that are affected by craniopharyngiomas.  They are often found because of learning difficulties, seizures, emotional or behavioral problems or because puberty has occurred at a young age.  The same anatomical issues that make a complete surgical resection difficult for craniopharyngiomas may also affect the surgical management of hypothalamic hamartomas.  Gamma Knife radiosurgery is a well-recognized therapy for this condition.

Meningioma: Meningiomas are tumors that form in the meninges, a fibrous membrane that lines the skull and spinal canal and surrounds the central nervous system. These tumors are often  very easily removed by a neurosurgeon, but in some cases they grow in places where surgical treatment is very risky for normal tissue. Because the Gamma Knife can treat these tumors irrespective of their location in the skull, it is a first choice option for treatment. It can also be used after a surgical operation to target any portion of the meningioma that the surgeon was unable to safely remove.  

Movement disorders:  Patients with Parkinson’s disease or essential tremor may be candidates for Gamma Knife radiosurgery.  Gamma Knife radiosurgery can deliver high doses of radiation to specific targets located deep in the brain, changing their function and decreasing tremor.

Pituitary tumors: The pituitary gland controls hormonal activity for the thyroid, adrenal, reproductive glands, as well as helps regulate metabolism of nearly all tissues in the body. A pituitary tumor (also known as a pituitary adenoma) can cause abnormal secretion of hormones or may simply cause problems by pressing on nearby normal brain, including the nerves responsible for vision. Surgery and medications have well-defined roles in the management of pituitary tumors, but because these treatments may not be able to eradicate pituitary tumors, Gamma Knife radiosurgery is often a treatment of choice for this type of abnormality.

Trigeminal neuralgia: This condition is associated with disabling facial pain from abnormal nerve signaling. Although medications have been shown to be able to help control the condition, it generally worsens over time and neurosurgical interventions are required to help control the pain.  Gamma Knife radiosurgery can provide pain relief equivalent to other, more invasive procedures for patients with trigeminal neuralgia.

Prepping for the procedure

Prior to the procedure, patients will be asked to provide a complete medical history and may have to undergo a complete physical examination to ensure they are in good health. Blood tests and other diagnostic tests may be performed. It is important for patients to notify their health care provider about any sensitivities or allergies to medication, latex, tape, contrast dyes, iodine or anesthetic agents.

Patients should notify their health care provider of all medications – prescription and over the counter – and supplements they are taking at the time of the procedure. If the patient has a history of blood clots, they should notify a team member. The attending neurosurgeon and radiation oncologist who will be treating the patient with the Gamma Knife will review all treatment options and discuss the risks specific to the treatment.

A Gamma Knife procedure typically goes as follows:

  1. A lightweight frame is attached to the patient’s head.
  2. Local anesthesia is used before the frame is secured in place.
  3. The patient then has an MRI imaging study and for some patients, a CT scan as well.
  4. Data from the imaging study is transferred into the treatment planning computer.
  5. The treatment team uses advanced software to determine the treatment plan.
  6. When the individual treatment plan is completed, the patient is placed on the Gamma Knife couch and precisely positioned.
  7. The patient is then moved automatically, head first into the machine, and treatment begins.
  8. Actual treatment time varies based on the condition being treated and its location. However, the procedure typically lasts from 15 minutes to an hour or more, during which time the patient feels nothing.
  9. Following treatment, the patient is automatically moved out of the machine, and the head frame is removed.

Gamma Knife treatment is an outpatient procedure. The patient will be observed for a period of time and discharged home. Patients will not have a great amount of pain from the procedure. Over the counter medications such as Tylenol or Motrin will alleviate any discomfort.

Follow up

The physicians will want to see patients in their office approximately six weeks after Gamma Knife radiosurgery. MRI usually will be repeated several months after the procedure, with the exact timing dependent on the patient’s diagnosis.

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Northern Westchester Hospital is the only facility between New York City and Syracuse with the expertise and technology to offer Gamma Knife Perfexion radiosurgery.