Parkinsonism may aggravate dysphagia in myotonic dystrophy type 1: two case reports

INTRODUCTION: Weakness of trunk muscles, fatigue and reduced mobility are features of myotonic dystrophy type 1 (DM1) and may also characterize patients with extrapyramidal disorders. Dysphagia is common in DM1 and parkinsonism and can be predominant compared to other symptom, often requiring surgical tratment. METHODS: We describe two cases of patients with DM1 and parkinsonism who arrived at our Center for worsening dysphagia and who showed very similar and peculiar clinical features. CASE REPORTS: The first patient presented initially at the outpatient clinic reporting a 7 year history of progressive difficulties in swallowing and movement slowness. Neurologic examination showed a general bradykinesia, plastic rigidity of upper limbs, diffuse hypotrophy and deep tendon reflexes weakness. MRI scan of brain and spine was unremarkable, but neurophysiological evaluation revealed diffuse myotonic discharges on distal limb muscles. Genetic testing confirmed DM1 diagnosis (CTG range E1). The second patient, presented with an initial diagnosis of parkinsonism due to a 10 years history of gait impairment, generalized weakness and dysphagia. Due to low back pain a neurophysiological study was performed after 5 years from diagnosis of parkinsonism detecting diffuse myotonic discharges and genetic testing confirmed diagnosis of DM1 (CTG range E2). Percutaneous endoscopic gastrostomy (PEG) was severe and burdensome for both patients. To date, only one case of molecularly confirmed DM1 along with parkinsonism has been described. We have described two cases of DM1 and parkinsonism in which swallowing function has been affected by a synergic effect triggered by both muscle condition and extrapyramidal disease.