An electrophysiological method to define the treatment with botulinum toxin in neurogenic dysphagias with cricopharyngeal dysfunction

Abstract

Some studies have indicated the efficacy of the botulinum toxin for the treatment of dysphagia in different neurological diseases, such as parkinsonian syndromes and stroke, by injecting the toxin into the cricopharyngeal (CP) muscle, the main part of the upper oesophageal sphincter (UOS). There are some electrophysiological investigations able to quantify abnormalities in CP muscle relaxation in the hypo-pharyngeal phase and also to evaluate other abnormalities in oral and pharyngeal phases of swallowing. In the present study we used an electrophysiological method, before and after botulinum toxin injection in the CP muscle, to evaluate oropharyngeal swallowing in parkinsonian syndromes, strokes, and multiple sclerosis with neurogenic dysphagia due to insufficient or absent UOS relaxation. Statistical analysis showed that less than 50% of our patients improved their deglutition after the treatment. The patients unresponsive to the treatment showed other swallowing abnormalities such as prolonged interval between propulsive tongue action and start of elevation of pharyngeal–laryngeal structures, insufficient or prolonged pulling action of the tongue. This study indicates that botulinum toxin inefficacy can be due to the association of different swallowing abnormalities to the CP spasm. The electrophysiological investigation of oropharyngeal swallowing can be very useful to select patients for botulinum toxin treatment of the CP muscle.