Feasibility Study of ExAblate Thalamotomy for Treatment of Chronic Trigeminal Neuropathic Pain

Inclusion Criteria: * Men and women, between 18 and 75 years, inclusive * Subjects who are able and willing to give consent and able to attend all study visits * Severe chronic, trigeminal neuropathic pain of ≥6 months duration. * Pain is medication-refractory to adequate trials of at least 3 prescription medications commonly used for symptomatic relief of neuropathic pain with current adjunctive use of at least one medication. An adequate medication trial is defined as a therapeutic dose of each medication without sufficient effect. * Pain is treatment-resistant to at least one interventional therapies including injections, procedures, neuromodulation, and surgery. * Able to communicate sensations during the focused ultrasound treatment * Stable prescribed doses of all symptomatic pain medications for 30 days prior to study entry and for the duration of the 3-month blinded phase of the study. Exclusion Criteria: * Craniofacial pain syndromes related to malignancy of the head and neck * Idiopathic trigeminal neuralgia * Headache syndromes like migraine, cluster headache * Temporomandibular joint syndrome * Atypical facial pain or pain related to a somatoform disorder * Subjects with active psychiatric illness will be excluded. For the purpose of this study, active psychiatric illness includes: * Exhibiting current suicide ideation and/or a history of suicide attempt within past 2 years * been hospitalized for the treatment of a psychiatric illness within the past 2 years * received transcranial magnetic stimulation for depression treatment * received electroconvulsive therapy for depression * Any presence or history of psychosis will be excluded. * Subjects with unstable cardiac status including: * Unstable angina pectoris on medication * Subjects with documented myocardial infarction within six months of protocol entry * Significant congestive heart failure defined with ejection fraction \< 40 * Subjects with unstable ventricular arrhythmias * Subjects with atrial arrhythmias that are not rate-controlled * Severe hypertension (diastolic BP \> 100 on medication) * Subjects with standard contraindications for MR imaging such as non-MRI compatible implanted metallic devices including cardiac pacemakers, size limitations, etc. * Receiving anticoagulant (e.g. warfarin) or antiplatelet (e.g. aspirin) therapy within one week of focused ultrasound procedure or drugs known to increase risk or hemorrhage (e.g. Avastin) within one month of focused ultrasound procedu…