Bulbar Problems Self-Reported by Children and Adults with Spinal Muscular Atrophy

Background: Spinal muscular atrophy (SMA) is hereditary motor neuron disorder, characterised by the degeneration of motor neurons and progressive muscle weakness. It is caused by the homozygous loss of function of the survival motor neuron (SMN) 1 gene. SMA shows a wide variability of disease severity. Objective: To investigate self-reported bulbar problems in patients with SMA, and their relationship to age, functional motor scores and active maximum mouth opening. Methods: We used the Diagnostic List of Dysphagia and Dysarthria in (pediatric) patients and relevant recent clinical data from the national SMA database. Results: The 118 included patients with SMA frequently reported jaw problems (34%), fatigue associated with mastication (44%), choking (56%) and intelligibility problems (27%). Jaw, mastication and swallowing problems frequently occurred in combination with each other. There was an increase of reported bulbar problems in patients with SMA type 3a, older than 30 years of age, compared to younger patients of this SMA type. The Hammersmith Functional Motor Scale Expanded scores showed a negligible correlation with jaw and mastication problems, a low negative correlation with swallowing problems and a moderate negative correlation with intelligibility problems. Reduced mouth opening showed a significant, but low correlation with bulbar complaints in patients with SMA type 2. Conclusions: Fatigue associated with mastication and swallowing problems were frequently reported complaints. Patients 30 years and older with milder forms of SMA showed an increase of self-reported bulbar problems.