What is Gamma Knife surgery?
The Gamma Knife is a precise and powerful tool for treating certain tumors and vascular malformations by creating lesions in the ventral portion of the internal capsule in the brain. It is actually not a knife at all, but an instrument that emits finely focused beams of gamma radiation. Delivered through holes (or portals) in a device known as a collimator, each beam crosses at a single point. It is only at that point that enough radiation is delivered to affect the diseased tissue. The beam is so finely focused that it spares the nearby tissue, so its extreme accuracy (to a half millimeter) is one of its greatest advantages. Gamma Knife surgery is non-invasive; radiation is delivered through the intact skull.
How does it work to help OCD?
The Gamma Knife targets areas deep in the brain that have connections to regions responsible for causing OCD symptoms. Lesioning these connections may lead to symptom relief.
What are the benefits?
Treatment with a Gamma Knife capsulotomy may reduce OCD symptoms.
What are the risks?
Short-term risks include nausea, pain, and claustrophobia from the gamma chamber. You may have a headache after the procedure. Longer-term risks of gamma capsulotomy are mainly brain swelling due to the radiation, which, if significant, is treated with a cortisone-like steroid drug. Clinical symptoms can include dizziness, blurred vision, headaches, and balance problems. The corticosteroid medications prescribed for edema can sometimes produce an unstable mood, including mood elevation or mania. That mood is temporary and will resolve after the cortisone-like medication is stopped. A small number of patients have also developed cysts (fluid-filled sacs) near the lesion site; these cysts were symptomatic in one patient, and neurosurgical treatment was needed. As with any surgical procedure, there is a risk of death.
Who is eligible for surgery?
You may be eligible to receive gamma ventral capsulotomy if you:
- Are between the ages of 18 and 70 years old.
- Have intractable OCD resulting in major functional impairment, and are in good general health.
- Have health insurance that will pay for the procedure and associated clinical visits (such as neurological, neuropsychological assessments), or are willing to pay out of pocket.
Specific inclusion/exclusion criteria will be discussed with you during the initial screening.
What is the screening process?
The screening process has two main stages:
- Collecting information.
- An in-person evaluation.
If a participant appears eligible based upon presentation of initial records, he or she will undergo an evaluation in person. This evaluation will take place at Butler Hospital and will last approximately eight hours. The data will be reviewed by our Psychiatric Neurosurgery Committee, a multidisciplinary team of clinicians who specialize in this treatment. This team will determine if you are eligible for the procedure.
If you are deemed eligible and elect to have the procedure, you will undergo a pre-surgical evaluation the week before the procedure. This will include extensive physical, neurological, and cognitive testing to determine there are no neurological reasons not to undergo radiosurgery.
Who will perform the procedure?
The procedure will be performed by a neurosurgeon (Wael Asaad, MD, PhD) at Rhode Island Hospital, in conjunction with the OCD treatment team from Butler Hospital (Steven Rasmussen, MD; Benjamin Greenberg, MD, PhD; Nicole McLaughlin, PhD). A radiation oncologist also helps oversee the process to ensure correct dosing.
Where is the procedure performed?
The procedure (including a pre-operative MRI) will be carried out at Rhode Island Hospital. All associated clinical assessments and follow-up visits will take place at Butler Hospital. The research brain scans (if you choose to participate in associated studies) will be completed at the Brown University Magnetic Resonance Facility (MRF).
Is there a great distance between Butler Hospital, Rhode Island Hospital and Brown University?
No. Each of these facilities is within 10 – 15 minutes travel time by car. Most out-of-state patients rent a car, although cab and public bus transportation is available. Butler Hospital and Rhode Island Hospital have adequate patient parking. Brown University parking will be provided also.
Are there reasonable overnight accommodations available near the hospitals and university?
Yes, there are various accommodations nearby. A few may accommodate their fee for out-of-state hospital patients.
Where do I follow-up after the procedure?
You will continue follow-up with your local treatment providers. Clinicians from our team will also continue to remain in touch with you by phone. Patients also return for follow-up in person one year after the treatment.
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