Evaluation of the Cortical Silent Period of the Laryngeal Motor Cortex in Healthy Individuals.
Objective:This work aimed to evaluate the cortical silent period (cSP) of the laryngeal motor cortex (LMC) using the bilateral thyroarytenoid (TA) muscles with transcranial magnetic stimulation (TMS).Methods:In 11 healthy participants, fine-wire electromyography (EMG) was used to record bilateral TA muscle responses to single pulse TMS delivered to the LMC in both hemispheres. Peripheral responses to stimulation over the mastoid, where the vagus nerve exits the skull, were collected to verify the central origin of the cortical stimulation responses by comparing the latencies.Results:The cSP duration ranged from 41.7 to 66.4 ms. The peripherally evoked motor-evoked potential (MEP) peak occurred 5-9 ms earlier than the cortical responses (for both sides of TAs:p< 0.0001) with no silent period. The right TA MEP latencies were earlier than the left TA responses for both peripheral and cortical measures (p≤ 0.0001).Conclusion:These findings demonstrate the feasibility of measuring cSP of LMC based on intrinsic laryngeal muscles responses during vocalization in healthy volunteers.Significance:The technique could be used to study the pathophysiology of neurological disorders that affect TA muscles, such as spasmodic dysphonia. Further, the methodology has application to other muscles of the head and neck not accessible using surface electrodes.
Divisions of Physical Therapy and Rehabilitation Science, Department of Rehabilitation Medicine, School of Medicine, University of Minnesota Minneapolis, MN, USA.
Mo
M
Chen
Divisions of Physical Therapy and Rehabilitation Science, Department of Rehabilitation Medicine, School of Medicine, University of Minnesota Minneapolis, MN, USA.
Rebekah L S
RL
Summers
Department of Otolaryngology-Head and Neck Surgery, University of Minnesota Minneapolis, MN, USA.
George S
GS
Goding
Department of Communication Sciences and Disorders, University of Wisconsin River Falls Campus River Falls, WI, USA.
Sharyl
S
Samargia
Department of Communication Sciences and Disorders, James Madison University Harrisonburg, VA, USA.
Christy L
CL
Ludlow
Divisions of Physical Therapy and Rehabilitation Science, Department of Rehabilitation Medicine, School of Medicine, University of Minnesota Minneapolis, MN, USA.
Cecília N
CN
Prudente
Divisions of Physical Therapy and Rehabilitation Science, Department of Rehabilitation Medicine, School of Medicine, University of Minnesota Minneapolis, MN, USA.
Teresa J
TJ
Kimberley
TMS; Transcranial magnetic stimulation; cSP; cortical silent period; fine wire electrode; larynx; motor cortex excitability