EMG Motor Neuron Disease Anal Sphincter

Part1Establish reference values of quantitative electromyography of external anal sphincter in healthy volunteersObjective:To establish a practical reference range on anal sphincter electromyography (EMG) of healthy volunteers with different ages and genders. The impact factors on the ranges, especially childbirth experience, were investigated. A clinical usable reference range on anal sphincter EMG adapted to various subject characteristics was established.Methods:A group of62healthy volunteers was recruited through public recruitment for the normative value study of anal sphincter EMG, which including37women with various childbirth experiences and25men. Motor unit potentials (MUPs) were obtained from bilateral external anal sphincter (EAS) of each subject using multi-MUP analysis. For each subject, the mean values of each MUP parameter (including duration, amplitude, area, mean number of turns, mean number of phases) and the parameters of percentage of polyphasicity and satellite rate were calculated. The impacts of subject characteristics (including genders, ages and childbirth experiences) on the anal sphincter EMG parameters were analyzed. Further, the reference values of each EMG parameter were statistically calculated for various subject characteristics.Results:Gender (P=0.019) and vaginal delivery experience (P=0.002) influenced the MUP parameter of duration, vaginal delivery experience also influenced the parameter of satellite rate (P=0.014), and ages did not significantly affect any EMG parameters except mean number of phases (P=0.007) Accordingly, the noramtive values were calculated respectively for subjects with different clinical characteristics:noramtive ranges of durations were7.91-12.19ms for men,7.43-10.47ms for women without vaginal delivery experiences and7.50-13.54ms for women with vaginal delivery experiences; the upper limits of satellite rates were13%for men and women without vaginal delivery experiences and20%for women with vaginal delivery experiences.Conclusion:Ages, genders, and vaginal delivery experience impact on anal sphincter EMG with different degree. According to the different impact factors, some practical reference values were determined. Part2The dysfunction of micturition and defecation and the characteristics of external anal sphincter electromyography in amyotrophic lateral sclerosis patientsObjective:To explore whether Onuf’s nuclei were involved in ALS; to investigate the incidence rate and the features of dysfunction of micturition and defecation in ALS patients and its relationship with the involvement of Onuf s nuclei; to discriminate the most common causes of micturition and defecation dysfunction of ALS patients.Methods:50cases of ALS were enrolled in PUMCH (Peking Union Medical College Hospital) between December2012and December2013.62healthy volunteers (the same as the first part) were as normal controls. For ALS patients, the clinical features were recorded and a detailed questionnaire covering storage and voiding of urine and feces respectively were completed, meanwhile, anal sphincter EMG was done using multi-MUP analysis for each patient and normal subject. To investigate whether Onuf s nuclei were involved in ALS, comparison of anal sphincter EMG between ALS patients and normal controls and the ALS subgroups were done. By the analysis of the results of the questionnaire, the incidence rate and the features of dysfunction of micturition and defecation in ALS patients were established. The causal relationship between Onuf s nuclei involvement and the occurrence of micturition and defecation dysfunction in ALS patients was explored by analyzing the relationship between the dysfunction of micturition and defecation and the abnormality of anal sphincter EMG. In addition, the most common causes of micturition and defecation dysfunction in ALS were discussed.Results:Compared with healthy volunteers, MUP parameters of amplitude (P=0.008) and area (P=0.001) were higher in ALS patients. The analysis of subgroups of different onset position showed that the average number of phases (P=0.040), the percentage of polyphasicity (P=0.037) and satellite rate (P=0.000) were higher in lower limbs onset group than other groups. Micturition and defecation dysfunction was detected in9of50(18%) ALS patients. Constipation (4/50) and urine urgency (4/50) were the most common symptom of micturition and defecation dysfunction in ALS patients, followed by powerlessness (2/50). The results of anal sphincter EMG of9ALS patients with micturition and defecation dysfunction were in normal ranges. There were no significant differences in any of the parameters of anal sphincter EMG between ALS patients with and without micturition and defecation dysfunction.4patients with constipation have lower (without statistical significance) mean score on ALSFRS-R scale, limbs function and respiratory function than patients without such symptom.4patients with urine urgency were predominantly upper motor neuron involved; ALS patients with predominant upper motor neuron involvement have higher incidence of urine urgency (P=0.000).2patients with powerlessness have lower mean score on ALSFRS-R scale (P=0.035), limbs function (P=0.020) and respiratory function (P=0.002) than patients without such symptom. According to this comparison analysis and related reviews, reduced activity, gastrointestinal dysfunction from abnormal autonomic nerve involvement, severe upper motor neuron damage and general powerlessness with respiratory muscle weakness might be the main causes of micturition and defecation dysfunction in ALS patients.Conclusion:Onuf’s nuclei might be mild involved in ALS.18%of ALS patients have complained of micturition and defecation dysfunction. Constipation, urgency and powerlessness were the main types of micturition and defecation dysfunction and they were not related to the involvement of Onuf’s nuclei. A detailed history and neurological examination may have considerable clinical significance for detecting the causes of micturition and defecation dysfunction in ALS patients.