5. Vocal cord paralysis in children: A new neurophysiological approach for diagnosis and functional prognosis

Abstract

To establish the possibility to use the methodology of recording corticobulbar motor evoked potentials (CoMEPs) from cricothyroid muscles (CTHY) and vocal cord elicited by transcranial electrical stimulation (TES), as diagnostic tool for predicting function recovery in children with vocal fold immobility (VFI). We included six children (mean age: 4.7 years; range: 2–9 years) with diagnosis of cord immobility that underwent video-fibro-endoscopy procedure. Under general anaesthesia, we used TES by stimulation over C3/Cz or C4/Cz to elicit CoMEPs. To record CoMEPs from vocal muscles we used two hook wire electrodes (76 micron diameter) passing through a 27-gauge needle endotracheally placed in the vocal muscles after intubation. Recording of CoMEPs in the vocal muscles after TES was successfully performed bilaterally in 4 patients and monolaterally in two patients. TES over the right or left hemisphere elicited responses bilaterally. The mean onset latency for the vocal muscles was 16.4 ± 3 ms. The possibility to record CoMEP from vocal muscle was a positive prognostic feature for clinical improvement. This method shows the ability to evaluate the functional integrity of corticobulbar pathways in a reliable manner and adds an additional tool in the diagnosis and prognosis of VFI.