Effects of Vagus Nerve Stimulation on Sleep-related Breathing in Epilepsy Patients

Authors

  • Mary Marzec,

    1. Michael S. Aldrich Sleep Disorders Laboratory and the Epilepsy Program, Clinical Neurophysiology Section, Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Jonathan Edwards,

    1. Michael S. Aldrich Sleep Disorders Laboratory and the Epilepsy Program, Clinical Neurophysiology Section, Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Oren Sagher,

    1. Michael S. Aldrich Sleep Disorders Laboratory and the Epilepsy Program, Clinical Neurophysiology Section, Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Gail Fromes,

    1. Michael S. Aldrich Sleep Disorders Laboratory and the Epilepsy Program, Clinical Neurophysiology Section, Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Beth A. Malow

    1. Michael S. Aldrich Sleep Disorders Laboratory and the Epilepsy Program, Clinical Neurophysiology Section, Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Accepted March 1, 2003.

Address correspondence and reprint requests to Dr. B.A. Malow at Department of Neurology, Vanderbilt University Medical Center, 2100 Pierce Avenue, 320 MCS, Nashville, TN 37212-3375, U.S.A. E-mail: beth.malow@vanderbilt.edu

Abstract

Summary: Purpose: To describe the effects of vagus nerve stimulation (VNS) on sleep-related breathing in a sample of 16 epilepsy patients.

Methods: Sixteen adults with medically refractory epilepsy (nine men, seven women, ages 21–58 years) underwent baseline polysomnograms (PSGs). Three months after VNS therapy was initiated, PSGs were repeated. In addition, patient 7 had a study with esophageal pressure monitoring, and patient 1 had a continuous positive airway pressure (CPAP) trial.

Results: Baseline PSGs: One of 16 patients had an apnea–hypopnea index (AHI) >5 (6.8). Treatment PSGs: Five of 16 patients had treatment AHIs >5. Respiratory events were more frequent during periods with VNS activation (on-time) than without VNS activation (off-time; p = 0.016). Follow-up studies: Esophageal pressure monitoring in patient 7 showed crescendos in esophageal pressure during VNS activation, supporting an obstructive pattern. The CPAP trial of patient 1 showed that all respiratory events were associated with VNS stimulation at low CPAP levels. They were resolved at higher CPAP levels.

Conclusions: Treatment with VNS affects respiration during sleep and should be used with care, particularly in patients with preexisting obstructive sleep apnea. The AHI after VNS treatment remained <5 in the majority of patients and was only mildly elevated (<12) in five patients. In one patient, CPAP resolved VNS-related respiratory events.

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