Safety and Efficacy of Vagus Nerve Stimulation in Fibromyalgia: A Phase I/II Proof of Concept Trial.
SourceDepartments of Radiology Psychiatry Neuroscience, UMDNJ-New Jersey Medical School, Newark, New Jersey Department of Veterans Affairs, New Jersey Health Care System, East Orange, New Jersey Departments of Neurosurgery Pain Medicine & Palliative Care, Beth Israel Medical Center, New York, New York Department of Epidemiology and Health Promotion, College of Dentistry, New York University, New York, New York William S. Middleton Memorial Veterans Hospital and the Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, USA.
AbstractObjective. We performed an open-label Phase I/II trial to evaluate the safety and tolerability of vagus nerve stimulation (VNS) in patients with treatment-resistant fibromyalgia (FM) as well as to determine preliminary measures of efficacy in these patients. Methods. Of 14 patients implanted with the VNS stimulator, 12 patients completed the initial 3-month study of VNS; 11 patients returned for follow-up visits 5, 8, and 11 months after start of stimulation. Therapeutic efficacy was assessed with a composite measure requiring improvement in pain, overall wellness, and physical function. Loss of both pain and tenderness criteria for the diagnosis of FM was added as a secondary outcome measure because of results found at the end of 3 months of stimulation. Results. Side effects were similar to those reported in patients treated with VNS for epilepsy or depression and, in addition, dry mouth and fatigue were reported. Two patients did not tolerate stimulation. At 3 months, five patients had attained efficacy criteria; of these, two patients no longer met widespread pain or tenderness criteria for the diagnosis of FM. The therapeutic effect seemed to increase over time in that additional participants attained both criteria at 11 months. Conclusions. Side effects and tolerability were similar to those found in disorders currently treated with VNS. Preliminary outcome measures suggested that VNS may be a useful adjunct treatment for FM patients resistant to conventional therapeutic management, but further research is required to better understand its actual role in the treatment of FM.
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