Up to 80% of patients with Parkinson disease and 30% of patients with amyotrophic lateral sclerosis (ALS) suffer from sialorrhea. Patients who fail medical and surgical therapy should be considered for external beam radiation therapy (EBRT). In this study, we conduct a systematic review to determine the dose and techniques used that result in greatest efficacy and lowest toxicity for the administration of EBRT in patients with Parkinson disease or ALS-associated sialorrhea.

This review included 216 patients from four prospective and six retrospective studies published from 1998 to 2014, with ALS or Parkinson disease who were treated with electron or photon EBRT for sialorrhea.

A total of 216 patients were treated with EBRT from 10 studies. The indication for EBRT was failure of alternative medical treatment in all ALS patients. For patients with Parkinson disease, EBRT was the primary mode of treatment in 68% of cases. Overall, 176 (81%) of 216 patients treated with EBRT for sialorrhea reported symptomatic improvement from baseline. The most common target was the inferior two-thirds of the bilateral parotid glands and the entire bilateral submandibular glands. The total number of patients who experienced short-term toxicity was 86 of 216 patients (40%). The total number of patients who experienced long-term toxicity was 24 of 207 (12%).

EBRT is an effective treatment for sialorrhea in patients suffering from ALS or Parkinson disease. Treatment to the bilateral submandibular glands and caudal parotid glands is the most common field arrangement.