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Sleep bruxism (SB) is a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep. We aimed to understand the abnormal networks related to the excitability of masticatory pathways in patients with SB. Eleven patients with SB and age- and gender-matched 20 healthy subjects were prospectively enrolled in our study. The masseter inhibitory reflex (MIR) after electrical stimulation and auditory startle reaction (ASR) were examined. For MIR responses, durations of early and late silent period (SP) were shorter and the degree of suppression of SPs was significantly lower in SB group in comparison to those obtained in healthy subjects. The ASR responses even of the masseter muscle, however, were similar between patients with SB and healthy individuals. Abnormal MIR provides support for the decreased inhibitory control of the central masticatory circuits in SB whereas normal ASR suggests the integrity and normal functioning of brainstem pathways mediating startle reaction. Although the sample size is small, our results are in line with previous findings and suggest an abnormally decreased inhibition in trigeminal motoneurons to masseter muscle rather than reticulobulbar pathways in patients with SB.

The aim of this study was to evaluate patients with vocal fold polyps using laryngeal electromyography (LEMG) for the presence of vocal fold paresis and to compare transnasal fiberoptic and rigid stroboscopic findings between polyp patients with normal LEMG and with vocal fold paresis. Thirty-five patients with a vocal fold polyp underwent transnasal fiberoptic laryngoscopy, rigid laryngostroboscopy, and LEMG. The findings were compared between the LEMG-confirmed vocal fold paresis patients and the normal LEMG patients. LEMG resulted in a diagnosis of unilateral or bilateral vocal fold paresis in 17 of 35 patients (48.6 %). More men than women with vocal fold polyps had vocal fold paresis (p < 0.05). The vocal fold paresis group had higher presence of axial rotation and hypomobility of vocal folds, higher asymmetry of vertical height of vocal folds, and less presence of longitudinal stretch of vocal folds (p < 0.05). Medial-lateral compression of the false vocal folds and anterior-posterior approximation of the larynx did not show any difference between the groups. No significant difference was found in vibratory wave characteristics between the groups through rigid laryngostroboscopy. Vocal fold paresis was present in almost half of the patients with vocal fold polyps. Paresis can only be accurately diagnosed with LEMG. Transnasal fiberoptic laryngoscopic examination is helpful to recognize vocal fold paresis in vocal fold polyp patients, while stroboscopic examination is not useful to identify it in vocal fold polyp patients.