EMG analysis of speech production of patients with Friedreich disease.
EMG activity from the orbicularis oris (superior and inferior), mentalis, depressor labii inferior (four lip muscles) and anterior belly of the digastric (one jaw muscle) was recorded during nonsense utterances produced at two speaking rates, conversational and fast, by 13 patients with Friedreich disease. The data were compared with those obtained from two normal subjects. At a conversational speaking rate, all patients showed a prolongation of anticipatory muscular activities and overall muscular activities. This abnormality might be an elemental feature of dysmetria. Hypotonia could also be considered as an explanation. At a conversational speaking rate, muscular synergia was better preserved than at a fast speaking rate. However, only five of 13 patients showed a normal EMG pattern with reciprocity between the muscular activities for rhythmical opening/closing movements of lips and jaw (/papapa/). For the same utterance produced at a fast speaking rate, no patient showed a normal EMG pattern. This abnormality might reflect dysdiadochokinesia. Production of the syllable /ba/ in response to an auditory signal showed a delay in the initiation of muscular activities which might be explained by hypotonia.
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INSERM, Laboratoire de Physiologie de la Motricité, CHU Pitié-Salpetrière, Paris.