Limitation of Intraoperative Transcranial Electrical Stimulation-Motor Evoked Potential Monitoring During Brain Tumor Resection Adjacent to the Primary Motor Cortex

Transcranial electrical stimulation-motor evoked potential (TES-MEP) is a valuable intraoperative monitoring technique during brain tumor surgery. However, TES can stimulate deep subcortical areas located far from the motor cortex. There is a concern about false-negative results from the use of TES-MEP during resection of those tumors adjacent to the primary motor cortex. Our study reports three cases of TES-MEP monitoring with false-negative results due to deep axonal stimulation during brain tumor resection. Although no significant change in TES-MEP was observed during surgery, study subjects experienced muscle weakness after surgery. Deep axonal stimulation of TES could give false-negative results. Therefore, a combined method of TES-MEP and direct cortical stimulation-motor evoked potential (DCS-MEP) or direct subcortical stimulation should be considered to overcome the limitation of TES-MEP.

Normative Temporal Data of Hyolaryngeal Movements during Swallowing / 대한연하장애학회지

OBJECTIVE: This study evaluated the temporal variables of hyolaryngeal movements during normal swallowing using kinematic analysis of the video fluoroscopic swallowing study (VFSS) to present the normal cut-off values of those variables. METHODS: Seventy-five healthy volunteers (17 men, 58 women) without swallowing dysfunctions were recruited to examine the swallowing of 2-ml diluted barium by a VFSS. Kinematic analysis was conducted by digitization of video files for movements of hyolaryngeal structures, including the vocal cords, hyoid bone, and epiglottis during normal swallowing. The time points and duration of hyolaryngeal movements were measured. The time points were the start point, maximal point, and the end point of the LE (Laryngeal Elevation), HE (Hyoid Excursion), and EF (Epiglottic Folding). The durations of LE, HE, and EF were obtained by subtracting the time of the start point from the time of the maximal point. The onset time of LE was defined as the reference time point (0 sec). The upper and lower limits of the 95% confidence interval were adopted as the normal cut-off values for the temporal variables of hyolaryngeal movements after transformation to a normal distribution. If a transformation formula to a normal distribution was not found in a variable, the values of the 2.5–97.5 percentile were adopted. RESULTS: The cut-off values of the maximal and end points of the LE were 0.281 to 0.916 sec, and 0.830 to 2.205 sec, respectively. The cut-off values of the start, maximal and end points of the HE were −0.233 to 0.400 sec, 0.320 to 0.874 sec, and 0.889 to 2.055 sec, respectively. The cut-off values of the start, maximal, and end points of the EF were 0.017 to 0.483 sec, 0.364 to 1.055 sec, and 0.774 to 1.773 sec, respectively. The cut-off values of the duration of LE, HE, and EF were 0.281 to 0.916 sec, 0.258 to 0.767 sec, and 0.255 to 0.787 sec, respectively. CONCLUSION: This study presented the normal cut-off values of temporal variables of hyolaryngeal movements during normal swallowing. This study can serve as a basis for classifying and analyzing the patterns of patients with dysphagia.