Efficacy of rTMS (Repetitive Transcranial Magnetic Stimulation) on Patients With Somatoform Pain Disorder

Efficacy of rTMS (Repetitive Transcranial Magnetic Stimulation) on Patients With Somatoform Pain Disorder

Efficacy of rTMS (Repetitive Transcranial Magnetic Stimulation) on Patients With Somatoform Pain Disorder

Chronic somatoform pain is common in psychiatric patients. Chronic somatoform pain causes significant distress and disrupts social functioning. Moreover, chronic somatoform pain often does not sufficiently respond to medication. Chronic somatoform pain is associated with medial pain system. The medial pain system is comprised of structures engaged in affect and motivation, such as medial thalamus and limbic structures. The medial pain system gets inhibitory control from motor cortex. Functional neuroimaging studies indicate that chronic somatoform pain is associated with hypoactivity of motor cortex, defective inhibitory process, and hyperactivity of medial pain system. Repetitive Transcranial Magnetic Stimulation (rTMS) is a safe and non-invasive tool to modulate neurophysiologic activity of the focal brain. Therefore, pain relief by rTMS can be obtained from motor cortex stimulation, restoration of defective inhibitory process, and deactivation of medial pain system. Studies have shown that motor cortex stimulation using rTMS can relieve pain in patients with neuropathic pain. However, to our knowledge, there is no rTMS study on chronic somatoform pain in psychiatric patients. The purpose of this study is to evaluate the effect of motor cortex rTMS on chronic somatoform pain.

Chronic somatoform pain is common in psychiatric patients. Chronic somatoform pain causes significant distress and disrupts social functioning. Moreover, chronic somatoform pain often does not sufficiently respond to medication. Chronic somatoform pain is associated with medial pain system. The medial pain system is comprised of structures engaged in affect and motivation, such as medial thalamus and limbic structures. The medial pain system gets inhibitory control from motor cortex. Functional neuroimaging studies indicate that chronic somatoform pain is associated with hypoactivity of motor cortex, defective inhibitory process, and hyperactivity of medial pain system. Repetitive Transcranial Magnetic Stimulation (rTMS) is a safe and non-invasive tool to modulate neurophysiologic activity of the focal brain. Therefore, pain relief by rTMS can be obtained from motor cortex stimulation, restoration of defective inhibitory process, and deactivation of medial pain system. Studies have shown that motor cortex stimulation using rTMS can relieve pain in patients with neuropathic pain. However, to our knowledge, there is no rTMS study on chronic somatoform pain in psychiatric patients. The purpose of this study is to evaluate the effect of motor cortex rTMS on chronic somatoform pain.

Patients receive high frequency rTMS applied to the motor cortex (M1 area). The treatment protocol consists of 10 sessions of rTMS. At each session, patients receive 30 stimulation trains (10 Hz, 4 sec, 100% motor threshold) with 26 sec inter-train interval, resulting in a total of 1200 pulses per session.

Inclusion Criteria: DSM-IV diagnosis of somatoform pain disorder, chronic Exclusion Criteria: Neurological disorder history of epilepsy