The effects of botulinum toxin injections into the cricopharyngeus muscle of patients with cricopharyngeus dysfunction associated with pharyngo-laryngeal weakness

This prospective, open study was carried out in order to assess changes in the swallowing and dietary status after injection of Botulinum toxin A (BoNT-A) into the upper esophageal sphincter (UES) in a series of patients with cricopharyngeus (CP) muscle dysfunction associated with pharyngo-laryngeal weakness during at least 1 year follow-up after treatment. Patients who had a cricopharyngeus (CP) muscle dysfunction associated with pharyngo-laryngeal weakness and who were at risk for aspiration were included in the study. The upper border of the cricoid cartilage was identified and the CP muscle localized using a standard electromyogram (EMG). The dose of BoNT-A was determined depending on the results of EMG performed just before the injection. Outcomes were assessed by the penetration-aspiration scale (PAS), the level of residue in the pyriform sinus and the National Institute of Health-Swallow Safety Scale (NIH-SSS) on a video fluoroscopic swallowing (VFSS) assessment, the patient’s subjective impressions of their ability to swallow by the Deglutition Handicap Index (DHI), and changes in dietary status by the Functional Oral Intake Scale. Eleven patients underwent the complete assessment of swallowing function at 1, 3, 6, and 12 months. After the first set of treatment, seven patients had a good response and four did not respond. A significant decrease in the PAS score (p = 0.03), the amount of residue (p = 0.04) and the NIH-SSS score (p = 0.03) was observed 3 months after the injection in comparison with the first VFSS before the treatment. A relapse of dysphagia occurred in 3 out of the 11 treated patients; at 3 and 4 months for 2 patients with a Wallenberg syndrome, and at 11 months for a patient with cranial nerve paralysis after a surgery for a glomus tumor. Two of them underwent a second injection. One patient had a good response and remained stable for at least 1 year. The second did not respond either to the second injection or to a myotomy of the cricopharyngeal muscle. The third one is waiting for further surgery (myotomy). Therefore, at the end of the study and after a follow-up of at least 12 months, 5 patients out of the 11 enrolled had a good result. Percutaneous injection of BoNT-A into the UES can be a useful solution to improve cricopharyngeal dysfunction, despite the underlying pharyngo-laryngeal weakness.