Chronic pain in Machado-Joseph disease

Abstract

Background: Machado-Joseph disease (MJD) is one of the most common forms of neurodegenerative ataxia characterized by remarkable phenotypic heterogeneity. Although patients frequently report pain, systematic evaluation of this clinical feature is lacking. Objectives: To compare the frequency of chronic pain among patients with genetically confirmed MJD, an age- and sex-matched healthy control group, and a disease control group of patients with amyotrophic lateral sclerosis (ALS).Methods: We included 70 patients with MJD, 20 patients with ALS, and 70 control subjects from 2 clinical centers. All individuals underwent assessment with a standardized pain questionnaire. In addition, we used a visual analog scale to quantify pain intensity. Results: Thirty-three patients with MJD (47%), 3 patients with ALS (15%), and 6 controls (9%) reported chronic pain. Lower back pain preceded ataxia in 6 patients with MJD. Twenty-nine patients with MJD had daily pain, which was continuous in 23. The mean visual analog scale score was 6.1 in patients with MJD. Pain was musculoskeletal in 26 patients with MJD, dystonic in 2, neuropathic in 2, and mixed in 3. Typically, pain was lumbar (n=17) or in the lower limbs (n=15). We did not find significant differences regarding duration of disease, sex, or severity of ataxia among patients with MJD with and without chronic pain. Expanded (CAG)(n) tandem repeats were longer in patients with MJD who experienced chronic pain (67.3 vs 65.2; P=.04). Conclusions: In our series, pain was significantly more frequent in patients with MJD than in controls. Chronic pain was a frequent and often disabling complaint among patients with MJD. The lower back was the most frequently reported location of pain in patients with MJD.