Radiation Therapy for Sialorrhea in Patients With Amyotrophic Lateral Sclerosis: A Case Series and Critical Review

Radiation therapy (RT) for sialorrhea has historically used 3-dimensional techniques that broadly irradiate both major and minor salivary glands. However, some reports indicate that treatment of minor salivary glands may contribute to excessive xerostomia. In this retrospective case series, we assessed the efficacy and tolerability of oral-cavity-sparing volumetric modulated arc therapy (VMAT) and bilateral electron field radiation for sialorrhea in patients with amyotrophic lateral sclerosis (ALS) and reviewed the relevant literature.

From 2014 to 2025, 6 patients with bulbar-onset ALS and medically refractory sialorrhea were treated with RT to the parotid and submandibular glands (20 Gy in 5 fractions) at a single institution. Five patients received VMAT with 6 MV photons, and one received bilateral 16 MeV electrons. Clinical response, medication use, toxicity, and dosimetry were assessed. A PubMed search using "sialorrhea," "RT," and "amyotrophic lateral sclerosis" was performed for the literature review.

At a median follow-up of 15.05 months (range, 3.0-61.7 months), 5 of 6 patients (83.3%) achieved symptomatic improvement, with an average 60% patient-reported reduction in salivation and ≥2 point improvement in ALS Functional Rating Scale saliva subscore. Two discontinued anticholinergics, and 1 achieved complete resolution for 3 years. Acute toxicities with VMAT were mild and self-limiting, most commonly parotitis and thickened secretions. The patient treated with electrons developed grade 2 mucositis, not observed with VMAT. Late toxicities, including xerostomia, were minimal and transient. Dosimetry showed higher larynx and oral cavity doses with electrons, whereas VMAT delivered slightly higher spinal cord doses. Critical literature review supported RT as an effective and well-tolerated intervention.

RT provides durable relief of refractory sialorrhea in ALS with manageable toxicity. VMAT response is comparable with historical outcomes and may offer dosimetric advantages that correlate with reduced acute toxicities, although its clinical benefit and cost-effectiveness warrant further validation.