Pain in Spinal Muscular Atrophy: A Questionnaire Study.

Objective: This study aimed to reveal the chronic pain prevalence in spinal muscular atrophy (SMA) patients and identify the clinical characteristics of these patients with chronic pain. The pain status was also investigated in SMA patients with chronic pain.

Methods: This cross-sectional study was conducted between July 2018 and December 2018. SMA type II and type III patients in Japan were mailed a survey questionnaire. The survey items were chronic pain prevalence, clinical characteristics, and motor function. Patients with chronic pain also answered questions on various pain status parameters: pain intensity, frequency, duration, location using body map, and factors that exacerbated and relieved pain.

Results: The questionnaire recovery rate was 61.1%. Sixty-four type II (mean age 17.3 ± 11.7 years) and 22 type III (mean age 44.9 ± 21.6 years) patients were eligible for inclusion. The prevalence of chronic pain in type II and III patients was 40.6% and 40.9%, respectively. Type II patients with chronic pain were more likely to report the inability to sit without manual support than those without pain (p = 0.03). Pain intensity in SMA patients was mild, but pain usually occurred daily, for prolonged durations, most often in the neck, back, and lower extremities. Sitting and high physical activity exacerbated pain the most.

Conclusion: The percentage of patients with SMA with chronic pain was high, at above 40%. Moreover, the pain experienced by patients with SMA was low in intensity but frequent and most common in the lower extremities.