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Somatosensory evoked potentials recorded from the human pedunculopontine nucleus region

Authors

  • I-Jin Yeh MD,

    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
    2. Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
    3. Department of Neurology, Songde Branch, Taipei City Hospital, Taipei, Taiwan
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  • Eric W. Tsang MSc,

    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
    2. Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
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  • Clement Hamani MD, PhD,

    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
    2. Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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  • Elena Moro MD, PhD,

    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
    2. Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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  • Filomena Mazzella RN,

    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
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  • Yu-Yan Poon RN,

    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
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  • Andres M. Lozano MD, PhD, FRCSC,

    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
    2. Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
    3. Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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  • Robert Chen MA, MBBChir, MSc, FRCPC

    Corresponding author
    1. Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
    2. Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
    3. Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
    • Toronto Western Hospital, McLaughlin Pavilion, 7th Floor Room 411, 399 Bathurst Street, Toronto, Ontario M5T 2S8, Canada
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  • Potential conflict of interest: Funded by the Canadian Institutes of Health Research grant number MOP15128.

Abstract

The pedunculopontine nucleus region (PPNR) is an integral component of the midbrain locomotor region and has widespread connections with the cortex, thalamus, brain stem, cerebellum, spinal cord, and especially, the basal ganglia. No previous study examined the somatosensory connection of the PPNR in human. We recorded somatosensory evoked potentials (SEP) from median nerve stimulation through deep brain stimulation (DBS) electrodes implanted in the PPNR in 8 patients (6 with Parkinson's disease, 2 with progressive supranuclear palsy). Monopolar recordings from the PPNR contacts showed triphasic or biphasic potentials. The latency of the largest negative peak was between 16.8 and 18.7 milliseconds. Bipolar derivation revealed phase reversal with median nerve stimulation contralateral to the DBS electrode in 6 patients. There was no difference in SEP amplitude and latency between on and off medication states. We also studied the high frequency oscillations (HFOs) by filtering the signal between 500 and 2,500 Hz. The HFOs could be identified only from contralateral stimulation and had intraburst frequencies of 1061 ± 121 Hz, onset latencies of 13.8 ± 1.2 milliseconds, and burst durations of 7.3 ± 1.1 milliseconds. Among the 10 recordings with HFOs, only 1 had possible phase reversal in the bipolar derivation. Our results suggest that there are direct somatosensory inputs to the PPNR. The slow components and HFOs of the SEP have different origins. © 2010 Movement Disorder Society.

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