Introduction>
Myotonic dystrophy (DM1) is the most common type of adult-onset myotonic dystrophy. DM1 is inherited in an autosomal dominant manner. It is a multi-systemic disorder characterized by skeletal muscle weakness, myotonia, cardiac conduction abnormalities, cataracts, and other abnormalities. Patients with DM1 who have cardiac arrhythmias are at risk for stroke but the incidence of cerebral strokes is quite low. Therefore, we report a case of an adult-onset DM1 who developed lateral medullary infarction without well-known risk factors.
Case>
A 50-year-old male patient was admitted with dizziness, sweating, numbness in the left face, left side weakness, and dysarthria. He was diagnosed with myotonic dystrophy 7 years ago but has never been treated because of mild symptoms. He had a typical hatchet face, frontal baldness, and atrophy of gastrocnemius muscles (Figure 1). Action myotonia and percussion myotonia was also shown in the physical examination. He was newly diagnosed with diabetes mellitus after admission. In Magnetic resonance imaging, left lateral medullary infarction was found (Figure 2). He had ptosis of the left eye and showed dysphagia which are the characteristics of patients with lateral medullary infarction. Also, he has ataxia with gait abnormalities and deterioration of fine motor skills. Respiratory failure with bronchopneumonia was developed after the admission and tracheostomy was performed. He received comprehensive physical therapy and occupational therapy twice a day. Also, training for dysphagia and respiratory therapy were performed. Typical myotonic discharges were detected in electromyography and normal findings were found in motor and sensory nerve conduction studies. In the genetic study, the Dystrophia Myotonica Protein Kinase (DMPK) gene on chromosome 19 with increased CTGs repeat in full-mutation was shown (Figure 3). In the electrocardiogram study, sinus bradycardia with 1st degree atrioventricular block and premature atrial complexes was detected. We investigated all the possible risk factors for infarction but there were no well-known risk factors except DM1, newly diagnosed diabetes mellitus, and cardiac arrhythmia. These may have been caused the acute cerebral infarction.
Conclusion>
In many cases, young adult-onset ischemic stroke can be caused by cardiac origin embolism such as atrial fibrillation. However, we report an unusual case of lateral medullary infarction in DM1 with first-degree atrioventricular block with premature atrial complexes and then demonstrate that cardiac problem with underlying diabetes mellitus may be associated with lateral medullary infarction in the patient with DM1.
Keywords>
Myotonic Dystrophy, Stroke, Lateral Medullary infarct, Respiratory failure, Cardiac arrhythmia |
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Figure 1. The face of patient. He showed hatchet face, weakness of both masseter muscles and ptosis of left eye. There were levin tube inserted due to dysphagia.
Figure 2. Diffusion Weighted Image MRI scan showed left lateral medullary infarction.
Figure 3. DMPK (Dystrophia Myotonica Protein Kinase) gene genotyping. The number of CTG (Cytokine Thymine Guanine) repeat sequences was more than 50 times in chromosome 19. It belonged to the full mutation range.
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