MR Guided Focused Ultrasound (FUS) for the Treatment of Trigeminal Neuralgia

Inclusion Criteria: 1. Clinical Diagnosis of Classical or Idiopathic TN refractory to medical therapy 2. Age greater than 21 and less than 75 years 3. Subjects who are able and willing to give consent and able to attend all study visits 4. Documented chronic, severe pain for more than 6 months duration 5. Failure to respond to the usual therapeutic regimen considered to be standard of care for Trigeminal Neuralgia. The patient should have failed a trial of at least two classes of therapeutic agents, including an anticonvulsant agent 6. Patient with Trigeminal Neuralagia who has either failed a prior surgical approach considered to be standard of care for TN (Micro-vascular decompression, radiofrequency, stereotactic, Radiosurgery or glycerol) or is not considered to be an acceptable candidate for one of those alternative options (due to anesthesia risk, medical comorbidities or Patient refusal despite counseling). 7. Central lateral thalamotomy is feasible based on evaluation of imaging studies 8. Patient able to communicate sensations during the Exablate TcMRgFUS treatment 9. Two members of the medical team have agreed upon inclusion and exclusion criteria. Exclusion Criteria: * Patient with contra-indications to MRI such as severe claustrophobia and metallic implants incompatible with MRI. 1. Severe psychiatric disorder such as uncontrolled depression, bipolar disorder, prior attempt at suicide or suicide ideation in preceding 12 months 2. Life expectancy less than 12 months 3. Anticoagulant or antiplatelet medications as well as underlying coagulopathy 4. Prior or currently implanted thalamic DBS 5. Pregnant ladies or women of childbearing age who are sexually active and not using contraception 6. Inability to provide informed consent, for example due to underlying cognitive impairment or aphasia 7. Presence of intracranial mass or an acute intracranial abnormality 8. Subjects with unstable cardiac status such as Unstable angina pectoris, documented myocardial infarction within 6 months of protocol entry and ejection fraction less than 40 9. Subjects exhibiting any behavior(s) consistent with ethanol or substance abuse as defined by the criteria outlined in the DSM-IV. 10. Severe hypertension (diastolic BP \> 100 on medication or persistently elevated SBP\>140 mmHg despite adequate antihypertensive medications) 11. History of immunocompromise including those who are HIV positive. 12. History of intracranial hemorrhage, traumatic brain injury or thalamic stroke. 13. Cerebrovascular disease (multiple CVA or CVA within 6 months) 14. Subjects with life-threatening systemic disease that include and not limited to the following will be excluded from the study participation: HIV, Liver Failure, blood dyscrasias, etc. 15. Subjects with a history of seizures within the past year 16. Individuals who are not able or willing to tolerate the required prolonged stationary supine position during treatment (can be up to 4 hours of total table time.) 17. Are participating or have participated in another clinical trial in the last 30 days 18. Skull Density Ratio (SDR) less than 0.4 ± 0.05 19. History of multiple sclerosis.