A Study of Amifostine for Prevention of Facial Numbness in Radiosurgery Treatment of Trigeminal Neuralgia

A Randomized, Placebo-controlled Trial of Amifostine for Prevention of Facial Numbness in Patients Receiving Stereotactic Radiosurgery for Trigeminal Neuralgia

Trigeminal neuralgia or tic douloureux is severe, often debilitating, facial pain that significantly impairs the patient's quality of life and health. Stereotactic radiosurgery has been shown to provide pain relief in majority of patients treated. However, a common side effect of radiosurgery is facial numbness. Our goal is to maximize pain control while minimizing side effects. To this end, the purpose of this study is to evaluate whether adding a drug, amifostine, at the time of radiosurgery will protect patients from facial numbness.

Patients will be evaluated by a multi-disciplinary team composed of radiation oncologists and neurosurgeons. Pretreatment pain, neurologic function (including facial numbness), and health related quality of life will be assessed. Patients will be treated in a single session with 75 Gy maximal dose covering a 6 mm segment of the retrogasserian cisternal portion of the trigeminal sensory root. Treatment will be delivered using the CyberKnife Robotic Radiosurgery System with the patient in the supine position. An aquaplast head mask will be used to ensure adequate immobilization during therapy. The target volume shall be the 6 mm segment of the retrogasserian cisternal portion of the trigeminal sensory root. Patients will receive subcutaneous injection of amifostine (500 mg) or placebo 30 minutes +/- 30 minutes prior to SRS. Facial pain will be assessed using the Visual Analog Scale and Short-form McGill Pain Questionnaire. Following SRS, patients will be followed at 1, 3, 6, and 9 months ±7 days. Facial numbness will be assessed using the Barrow Neurologic Institute (BNI) Facial Numbness Score. Patient reported BNI facial numbness scoring and complete cranial nerve exam by a physician will be performed pre-treatment and at follow-up visits.

Inclusion Criteria:

All patients age 18 years and older with typical trigeminal neuralgia, as determined by diagnostic criteria set by the International Headache Society, who are:

• Intolerant of or refractory to medical management; AND
• Not candidates for or refusing a surgical micro-vascular decompression.

Exclusion Criteria:

• Patients who present with pre-existing BNI grade III or IV facial numbness.
• Patients who have previously been treated with MVD.
• Patients who have previously had an ablative treatment, including prior SRS.
• Pediatric patients (age <18), pregnant women, and patients who are unable to give informed consent will be excluded.