Sympathetic skin responses in adult humans during sequential swallowing.

STUDY AIMS: Autonomic changes, especially those of sympathetic skin responses (SSR), during sequential water swallowing (SWS) have not been systematically investigated. This study aims to electrophysiologically examine these autonomic changes (SSR and heart rate) that occur during 50 ml sequential water swallowing from a cup. MATERIALS AND METHODS: Fifty-eight normal healthy adults were included in the study. Their submental muscle activity, respiratory activity, heart rate changes, and sympathetic skin responses were recorded during 50 ml water swallowing. In addition, we requested subjects to imagine drinking water as they did just before. The same recordings were performed during this imagination period. RESULTS: SSR appeared at the beginning and at the end of SWS in 52% of subjects. A first sympathetic skin response was evoked at the onset of SWS, and a second one appeared 8.6±1.7 seconds after the first one and at the end of swallowing. Similar double SSRs were also obtained during imagination in most investigated subjects (33 out of 35 of selected subjects in a total group of 58 subjects). Swallowing tachycardia was observed during the SWS-associated apnea period, but not during the imagination period. Heart rate significantly increased during the SWS-associated apnea period. CONCLUSION: The first SSR that appeared at the onset of swallowing is likely related to arousal. The appearance of a second response is a novel finding, which is probably related to the activity of subtil corticosubcortical networks. While discrete/single swallows can be used to evoke SSRs, SWS is unlikely to be clinically useful in its current form. In contrast, swallowing tachycardia could be a useful tool to examine dysphagic patients.

An EMG screening method (dysphagia limit) for evaluation of neurogenic dysphagia in childhood above 5 years old.

Oropharyngeal dysphagia is not rare in older children before the adult age, especially the patients with cerebral palsy. Non-invasive simple tests are needed for the evaluation of children with neurogenic dysphagia including the patients with cerebral palsy. So we aimed to evaluate non-invasive ways to screen for dysphagia in children and the usefulness of this almost new electrophysiologic method for the detection of dysphagia in children with cerebral palsy. Twenty-eight healthy children and 12 patients with cerebral palsy were investigated for the applicability of this method. The movement of the larynx was monitored using a simple piezoelectric wafer sensor and submental surface EMG activity was recorded by bipolar silver-chloride electrodes taped under the chin over the submental muscle complex. The onset and duration of pharyngeal swallowing was recorded from submental-suprahyoid muscles such as the mylohyoid-genitohyoid-anterior digastric complex. By this method, the maximal water volume capacity was measured in single swallows with progressively increasing water volumes, this was called 'dysphagia limit'. The healthy control children revealed to swallow the bolus at once maximally 11.2+/-0.4 and 2.5 ml in average. Dysphagia limit varied from 7 to above 20 ml water volume from age 5-16 years old. Patients with cerebral palsy had the dysphagia limit of 7.7+/-1.8 and 6.4 ml in average. The dysphagia limit was significantly reduced in patients with cerebral palsy (p<0.05). Dysphagia limit seemed to be less sensitive in demonstrating the oropharyngeal swallowing disorders in childhood period (90% in the adult dysphagic patients). But the majority of patients with cerebral palsy (58%) showed abnormality. This electrophysiologic method is completely non-invasive, devoid from any hazard and applicable to children above 5 years. It may be candidate as a screening test before selection of dysphagic children.

Oropharyngeal swallowing in craniocervical dystonia.

OBJECTIVE: To clarify the pathophysiology of dysphagia by electrophysiological methods. METHOD: Electrophysiological methods related to oropharyngeal swallowing were used to investigate 25 patients with cervical dystonia and 25 age matched normal volunteers. RESULTS: Dysphagia was suspected in 36% of patients with cervical dystonia on the basis of clinical assessment. The incidence of dysphagia increased to 72% on electrophysiological evaluation of pharyngeal swallowing. Submental muscle electromyographic (EMG) and laryngeal relocation times were significantly prolonged and the triggering time to swallowing reflex was significantly delayed. Some abnormalities seen in cricopharyngeal sphincter muscle EMG indicated that the striated sphincter muscle is hyperreflexive in some patients. CONCLUSION: Neurogenic dysphagia was more prominent and longer lasting than mechanical dysphagia, which was transient and varied from patient to patient. Although these electrophysiological methods were not suitable for detecting anatomical changes during swallowing, as in videofluoroscopic studies, observations supported the neurogenic cause of dysphagia in patients with any kind of cervical dystonia.