Myotonic Dystrophy Type 1 with Syringomyelia in a Young Patient

Myotonic dystrophy type 1 (DM1) is the most common disease causing muscle weakness and atrophy in adults. The prevalence of DM1 in China is not clear. DM1 is an autosomal dominant genetic disorder associated with the cytosine‑thymine‑guanine (CTG) repeat expansion in 3'untranslated region in dystrophia myotonica‑protein kinase (DMPK) gene on chromosome 19q13.3. In DM1, CTG pathological repeat numbers are more than 50. The size of CTG repeat expansion is associated with the time of clinical phenotypes onset and severity. The coexistence of DM1 and syringomyelia is rare. Here, we report DM1 coexisting with syringomyelia in a Chinese male patient. A 28‑year‑old man was admitted in Qilu Hospital of Shandong University in December 2013, who had difficulty in flexing his fingers after hands grip, mainly in cold weather, for more than 10 years. Sometimes, he felt tongue stiff and slurred speech. He was shy and never told above symptoms to any relatives. His mother mentioned that he had progressively walking disability, especially with his right leg during the last 2 years. The patient noticed the right calf thinner than the left calf 1 week ago. He received surgery for right parotid benign tumor 9 years ago. His grandfather died of lung cancer at the age of 59, his father died of gastric cancer at 50, and one uncle died of leukemia at 19. Moreover, his aunt was diagnosed with DM1 after a muscular biopsy at the age of 50. The patient's sister was asymptomatic until now [Figure 1]. His physical examination on admission revealed a typical hatchet face with incipient baldness and weakness of the bilateral eyelid closure but normal ocular movement. Percussion myotonia was present in the tongue, bilateral thenar, and upper arm muscles. He had difficulty in opening the mouth after biting down forcibly and extending the fingers after a hard fist. Right lower limb was thinner than the left by 6 cm, with muscle strength scale 4 and foot drop. Limbs muscular tone was normal. Right achille reflex was absent. There was left semi‑jacket‑like hypoalgesia. Bilateral Babinski's signs were negative. Skin scratch test was positive from T2 to T4 dominated areas. The laboratory tests showed triglyceride 1.94 mmol/L (normal range: 0.30–1.70 mmol/L), creatine kinase 243 U/L (normal range: 38–174 U/L), serum free thyroxine (FT4) 10.98 pmol/L (normal range: 12.00–22.00 pmol/L), follicle‑stimulating hormone (FSH) 19.52 U/L (normal range: 1.50–12.40 U/L), and luteinizing hormone (LH) 14.68 U/L (normal range: 1.70–8.60 …