Gamma Knife radiosurgery is a technique used for intracranial stereotactic radiosurgery . It may be useful for treating arteriovenous malformations of the brain.
What is the Gamma Knife radiosurgery for arteriovenous malformations?
AVM is a tangle of abnormal vessels. The arteries have thick walls and a muscular component appointed to regulate the amount of blood flowing at high pressure. In the veins, the blood instead has a low pressure and the walls of these vessels are thin and weak. In an AVM, blood flows at relatively high pressure but the walls of its vessels are weak and thin, similar to those of the veins. The vessels of the AVM are at a risk of failure which can result in bleeding – estimated between 2% and 4% for each year of an individual’s life. A sudden effusion of blood in the cerebrospinal fluid (subarachnoid hemorrhage) or in the brain can cause various symptoms ranging from: severe headache with stiff neck, visual disturbances, dizziness, instability, and / or nausea; up to stroke-like symptoms such as difficulty speaking, insensitivity, lack of strength in the limbs, difficulty walking, coma or death.
How is Gamma Knife radiosurgery for arteriovenous malformations performed?
The patient is lightly sedated and then given a local anesthesia, where the stereotactic frame is placed to subject the patient to imaging tests (brain MRI and cerebral angiography with gadolinium). The images will allow the specialist to plan for the most proper form of treatment. Once decided upon, the patient will lay with a stereotactic frame fixed onto the Gamma Knife bed. The treatment can last from one to six hours, depending on the location and size of the malformation that needs to be targeted.
What are the advantages to undergoing Gamma Knife radiosurgery for arteriovenous malformations?
Gamma Knife radiosurgery is a minimally invasive procedure , done in a single session and free of pain and surgical incisions. The procedure is almost always done on an outpatient basis and the patient is usually discharged the day after the treatment. In very rare cases, the malformation may be treated in two or three sessions in a row, being 24 hours apart.
Is Gamma Knife radiosurgery for arteriovenous malformations painful or dangerous?
The procedure is not painful, though the patient may feel pain during positioning of the four small metal pins to stabilize the helmet or discomfort in the groin where the catheter is inserted. During the actual treatment, the patient will undergo subtle movements of the head, though they will not experience any pain or noises. The risks associated with this procedure are: neurological disorders (estimated risk <5%), brain edema (estimated risk <5%); seizures(estimated risk <5%); infection of the superficial tissues (estimated risk <1%); and radio induced cancer (the risk is of a 10,000 in a time ranging from 5 to 30 years).
Which patients can undergo this procedure?
Patients with small arteriovenous malformations can undergo this procedure. The neurosurgeon who will visit the patient to confirm the indication for treatment.
The results of the procedure are not immediate . The patient will be informed of any additional examinations that need to be carried out during discharge. The radiation effect can take effect after months and / or years, during which time the risk of bleeding is the same as the previous treatment. Sometimes, Gamma Knife treatment may not be enough and further treatment may be necessary, such as Gamma Knife combined with surgery or embolization.
What steps should be taken to help prepare for this procedure?
A few days before undergoing the procedure, the patient will travel to Humanitas for pre-admission and will be subjected to a blood test, an electrocardiogram (ECG), and a medical examination for a complete compilation of medical records. It is important that the patient announce any allergies to medications or contrast agents, or claustrophobia. On the day of the procedure, the patient should be accompanied by a family member or an acquaintance and should have been fasting from midnight the night before. On the night before the procedure, the patient should cleanse themselves with a product-based disinfectant shampoo, such as chlorhexidine. It is best to avoid wearing any jewelry: brooches, hairpins, makeup, hair products, and artificial nails; but rather wear comfortable clothing and footwear, preferably with buttons or zippers.