Motor Cortex Stimulation for the Treatment of Chronic Facial, Upper Extremity, and Throat Pain.

Inclusion Criteria: 1. Males and females who are greater than 18 years of age. 2. Subject has a diagnosis of chronic pain involving the face, upper extremity, or throat, as determined by a review of medical records, history and physical examination. The types of chronic pain eligible for the study are: 1. Facial pain, including trigeminal neuralgia Type 1, trigeminal neuralgia Type 2, trigeminal neuropathic pain, trigeminal deafferentation pain, symptomatic trigeminal neuralgia, and postherpetic neuralgia. 2. Complex Regional Pain Syndrome (Types I and II) involving the arm. 3. Both chronic and episodic forms of refractory Glossopharyngeal Neuralgia (GN). 4. Deafferentation of the cervical spine leading to pain of the upper extremity. 5. Central pain syndromes resulting from a prior cerebrovascular insult occurring at least 5 years prior to the study. 3. Subject determined to be treatment-resistant for at least one year prior to the Screening Visit as demonstrated by clinical evidence (determined by review of medical records and discussion with referring pain specialist, anesthesiologist, or neurologist treating chronic pain). The patient must not have responded to treatment with three adequate regimens of medication including one in each of the following categories: antiepileptic drugs, opioids, and antidepressant medications. The trial period for each medication should be at least four weeks, and the two trials must be within the previous 5 years. 4. Subject has at least a score of 6 on the Visual Analog Scale of Pain at all three clinic visits prior to undergoing surgery. 5. Subject must be ambulatory. 6. Females who are postmenopausal, physically incapable of childbearing, or practicing an acceptable method of birth control. Acceptable methods of birth control include surgical sterilization, hormonal contraceptives, or double-barrier methods (condom or diaphragm with a spermicidal agent or intrauterine device \[IUD\]). If practicing an acceptable method of birth control, a negative urine pregnancy test result has been obtained at baseline Visits 1 and 2. 7. Subject is assessed by psychologist with respect to i) the role of psychological factors, including psychological comorbidities, in their chronic pain, ii) their ability to rate pain and make decisions during the extraoperative stimulation trial, and iii) to participate in decision-making capacity to provide informed consent. 8. Subject is able to read English, understand and cooperate with study procedures, and has signed a written informed consent form prior to any study procedures. Exclusion Criteria: 1. Subject had major surgery within three months prior to Baseline Visit 1 or has other surgery planned during the proposed study period. 2. Subject is determined by medical consultant to have medical contraindications to undergoing surgery. 3. Subject is pregnant or breast-feeding. 4. Subject has a history of alcohol or drug abuse within the past 6 months and dependence within the past year. 5. Subject has a medical illness/condition, co-morbid psychiatric illness, and/or abnormal diagnostic finding that would interfere with the completion of the study, confound the results of the study, or pose risk to the patient. 6. Subject has a diagnosis of mental retardation. 7. Subject has a distinct neurological condition not included in the list of chronic pain syndromes studied in this protocol, or a history of traumatic brain injury associated with loss of consciousness of \> 1 hour and/or intracranial/epidural/subdural bleeding. 8. Diagnosis of a somatoform pain disorder.