Botulinum toxin may help treat dysphagia

Nutrition Research Newsletter, Dec, 2006

Swallowing allows the ingestion of fluids and food without aspiration. There are a number of processes that are required for normal swallowing, including voluntary and reflexive motor control, as well as integrity of multiple cranial nerves and muscles. Dysphagia, disruption of normal swallowing, is usually a sequela of many neurological and neuromuscular disorders. Autonomic and/or peripheral neuropathy is a common complication of diabetes and is due to poorly controlled blood glucose and diabetic microvascular disease.

Dysphagia has been observed in diabetic patients. While all the phases of swallowing can be involved, oropharyngeal dysphagia due to hyperactivity of the cricopharyngeus (CP) muscle of the upper esophageal sphincter (UES) is the prevalent abnormality. No medical treatment for oropharyngeal dysphagia in patients with diabetic neuropathy has been describer thus far.

Recently, chemical myotomy of the CP muscle by botulinum neurotoxin type A (BoNT/A) has proved to be effective in reducing and even abolishing dysphagia due to UES hyperactivity of different neurological or non-neurological etiologies. Researchers set out to assess the safety and efficacy of BoNT/A injections into the CP muscle in diabetic patients with severe oropharyngeal dysphagia associated with diabetic autonomic and/or somatic peripheral neuropathy.

Sixty-eight type 2 diabetic patients (43 insulin dependent and 25 noninsulin dependent) with diabetes-associated neuropathy underwent neurological examination for the presence of neurogenic dysphagia. Fourteen of 68 patients complained of dysphagia for both solid and liquid foods. Twelve of them (8 men, 4 women, age range 59 to 68 years) with severe dysphagia for both solid and liquid foods agreed to undergo treatment with BoNT/A.

Swallowing function was evaluated clinically and by both videofluoroscopy and simultaneous needle electromyography (EMG) of the CP and pharyngeal inferior constrictor (IC) muscles. Based on clinical evaluation, four levels of dysphagia were considered: mild dysphagia (dysphagia for liquids), discrete dysphagia (dysphagia for solids or for liquids and solids), severe dysphagia (frequent tracheal aspiration and choking), and very severe dysphagia (patient fed by nasogastric tube or percutaneous endoscopic gastrostomy). Videofluoroscopy with modified barium swallowing was performed. Three different food consistencies of standardized bolus size were used: thin liquid, semisolid, and solid. BoNT/A was percutaneously injected into the CP muscle under EMG. For each patient, 30 units of botulinum toxin were injected in each side of the CP muscle.

BoNT/A induced the complete recovery of dysphagia in 10 patients and had a significant (P = 0.0001, analysis of vairiance [ANOVA]) improvement in 2 patients within 4 [ or -] 1.1 days (range 3 to 7). Clinical improvement was confirmed by vidoefluoroscopy and EMG.

These findings suggest a benefit from BoNT/A treatment in diabetic patients with dysphagia secondary to diabetic neuropathy.

D. Restivo, R. Marchese-Ragona, G. Lauri, et al. Botulinum Toxin Treatment for Oropharyngeal Dysphagia Associated with Diabetic Neuropathy. Diabetes Care: 29;2650-2653 (December, 2006). [Correspondence: Damiano Gullo, Division of Endocrinology, Garibaldi Hospital, via Palermo 636, Cantania 1-95121, Catania, Italy. E-mail: damiano.gullo@poste.it.]