Although
mexiletine effectively treats
myotonia, supply disruptions affected Europe between 2008-2018. MyoPath was a mixed-methods, cross-sectional, market research survey conducted January-June 2018 to evaluate consequences of limited access to/awareness of
mexiletine in people with
myotonia. Part A: qualitative structured interviews (clinicians; advocates for adult patients); Part B: quantitative online questionnaire completed by people with self-reported history of
myotonia. Part A: Interviews (clinicians, n=12; patient advocates, n=5; 12 countries) indicated poor
mexiletine awareness among general neurologists. Patients chose between living with
myotonia (other treatments were generally unsatisfactory) or importing
mexiletine. Part B: Questionnaire respondents,
myotonic dystrophy (DM)1, n=213; DM2, n=128; non-dystrophic
myotonia (NDM), n=41; other n=8; (11 countries). Of the respondents, 76/390 (20%) people with awareness of/access to
mexiletine described profound improvements in
myotonia and health-related quality of life following treatment. Respondents with NDM had greatest
mexiletine experience (n=28/41).
Mexiletine was associated with fewer falls, less muscle stiffness, increased mobility. Treatment interruptions worsened
myotonia and were associated with
fatigue,
pain,
dysphagia, breathing difficulty, impaired digestion, poor sleep. However, 36/54 (67%) of currently treated people expressed anxiety about
mexiletine's availability: this finding was expected (MyoPath was undertaken before
mexiletine's approval in NDM). MyoPath provides the largest European exploration of patients' views regarding impact of
mexiletine on
myotonia. Anticipated effects of
mexiletine differ between people with different
myotonic disorders:
myotonia is the main symptom in NDM but one of many potential symptoms affecting those with DM. Nevertheless, findings indicate substantial harm caused to people with
myotonia when
mexiletine awareness/access is limited.