Safety and efficacy of vagus nerve stimulation in fibromyalgia: a phase I/II proof of concept trial.

OBJECTIVE: 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.

Sleep structure and sleepiness in chronic fatigue syndrome with or without coexisting fibromyalgia.

INTRODUCTION: We evaluated polysomnograms of chronic fatigue syndrome (CFS) patients with and without fibromyalgia to determine whether patients in either group had elevated rates of sleep-disturbed breathing (obstructive sleep apnea or upper airway resistance syndrome) or periodic leg movement disorder. We also determined whether feelings of unrefreshing sleep were associated with differences in sleep architecture from normal. METHODS: We compared sleep structures and subjective scores on visual analog scales for sleepiness and fatigue in CFS patients with or without coexisting fibromyalgia (n = 12 and 14, respectively) with 26 healthy subjects. None had current major depressive disorder, and all were studied at the same menstrual phase. RESULTS: CFS patients had significant differences in polysomnograpic findings from healthy controls and felt sleepier and more fatigued than controls after a night's sleep. CFS patients as a group had less total sleep time, lower sleep efficiency, and less rapid eye movement sleep than controls. A possible explanation for the unrefreshing quality of sleep in CFS patients was revealed by stratification of patients into those who reported more or less sleepiness after a night's sleep (a.m. sleepier or a.m. less sleepy, respectively). Those in the sleepier group reported that sleep did not improve their symptoms and had poorer sleep efficiencies and shorter runs of sleep than both controls and patients in the less sleepy group; patients in the less sleepy group reported reduced fatigue and pain after sleep and had relatively normal sleep structures. This difference in sleep effects was due primarily to a decrease in the length of periods of uninterrupted sleep in the a.m. sleepier group. CONCLUSION: CFS patients had significant differences in polysomnographic findings from healthy controls and felt sleepier and more fatigued than controls after a night's sleep. This difference was due neither to diagnosable sleep disorders nor to coexisting fibromyalgia but primarily to a decrease in the length of periods of uninterrupted sleep in the patients with more sleepiness in the morning than on the night before. This sleep disruption may explain the overwhelming fatigue, report of unrefreshing sleep, and pain in this subgroup of patients.