The normal muscle activity during swallows and drinking has several graphic patterns which can be identified and described similar to EKG records when surface EMG is rectified and filtered. The method of EMG recording is quick and simple, and can be used for screening and evaluation purposes in outpatient and inpatient ENT departments. These parameters represent activities required for normal deglutition, and can be used to identify abnormalities in ENT patients, and provide a basis for comparison of swallowing performance both within and between patients. These normal data form a valuable basis for future comparison with patients in pre- and postoperative stages and in EMG monitoring during ENT treatment.

Aminoglycoside (AG) antibiotics are associated with several side effects, including a reversible nephrotoxicity and a permanent ototoxicity. Oxidative stress is thought to contribute to the pathophysiology of both conditions. We studied the possible protective effect of the antioxidant N-acetylcysteine (NAC) in gentamicin-induced hearing loss in hemodialysis patients. This study includes 53 hemodialysis patients scheduled to receive gentamicin for dialysis catheter-related bacteremia that were randomized to receive the antibiotic with or without NAC. Hearing function was assessed by the standard technique of pure-tone audiograms over a range of frequencies. Audiometric evaluations were performed at baseline, 1 week and at 6 weeks after the completion of gentamicin therapy. A total of 40 patients completed the study protocol with a mean duration of therapy of almost 15 days. At both 1 and 6 weeks after the completion of antibiotic therapy, there were significantly more patients exhibiting ototoxicity in the control group compared with the group receiving NAC. Additionally, significantly more patients in the control group had bilateral ototoxicity. The greatest otoprotective effect of NAC was noticed in the high audiometric tone frequencies. Taken together, our study suggests that NAC treatment may ameliorate gentamicin-induced ototoxicity in hemodialysis patients.

Surface electromyographic (sEMG) studies were performed on 300 normal adults to estimate normal values of sEMG records of muscle activity in the detection and evaluation of stages of normal swallowing. Our study was a prospective observational study of healthy volunteers. The parameters evaluated during swallowing include the timing, amplitude (voltage), and graphic patterns of activity of the orbicularis oris, masseter, submental, and laryngeal strap muscles covered by the platysma. Three tests were examined: voluntary single swallows of saliva ("dry" swallow), voluntary single water swallows ("normal"), and voluntary single swallows of excessive amounts of water (20 ml, "stress test"). Duration and amplitude of muscle activity in oral, pharyngeal, and initial esophageal stages of swallowing (mean + standard deviation, range + standard deviation) were measured for groups of adults of different ages (18-40, 41-70, 70+ years). Shapes of graphic records were evaluated relative to timing and voltage. The overall normal mean values for stage-by-stage duration of muscle activity during single swallowing were established for healthy adults. The duration of muscle activity in all tests showed insignificant increases with age except for the elderly group (70+) in which it was statistically significant (SPSS, chi2 criterion, 95% confidence interval, p < 0.05). There were no statistically significant gender-related differences in duration or amplitude of muscle activity during single swallowing for any age group (p > or = 0.05). We conclude that the rectified and filtered sEMG provides a noninvasive means to assess certain aspects of complex muscle activity in deglutition. Surface EMG of swallowing is a simple and reliable noninvasive screening method for evaluating swallowing with low levels of discomfort. Stage-by-stage evaluation of duration can be very important for diagnosing the etiology of dysphagia. The combined normative timing of events, amplitude, and graphic data can be used for evaluating complaints and symptoms, as well as for comparison purposes in pre- and postoperative stages and in EMG monitoring during otolaryngological or neurological treatment. These parameters represent stages required for normal deglutition and provide a basis for the comparison of swallowing performance both within and between patients.