Diffusion Tensor Imaging Magnetic Resonance Imaging (DTI MRI) as a Correlate to Pain Relief and Facial Numbness in Patients Following Stereotactic Radiosurgical Rhizotomy for Trigeminal Neuralgia

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 1) intolerant of or refractory to medical management and 2) not candidates for or refusing a surgical micro-vascular decompression, will be evaluated for treatment with SRS. * ECOG or Karnofsky Performance Status will not be employed, but patients must be sufficiently healthy to tolerate all study procedures. * Patient must exhibit the ability to understand and the willingness to sign a written informed consent. Exclusion Criteria: * Exclusion criteria * Patients who present with pre-existing facial numbness. * Patients MRI contraindications (e.g., pacemaker or defibrillator, cochlear implant, brain aneurysm clip, etc.) * 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.