Grand Rounds

Constipation as a Presentation of Duchenne Muscular Dystrophy

Dhruv Gandhi, Ira Shah
Department of Pediatric Gastroenterology and Hepatology, BJ Wadia Hospital for Children, Mumbai, India

Address for Correspondence: Dhruv Gandhi, 5B/13 Shyam Niwas, Breach Candy, Mumbai-400026, Maharashtra, India. Email: dhruvgandhi2610@gmail.com

Keywords: Chronic intestinal pseudo-obstruction, Gastric dilatation, Sigmoid volvulus, Bowel dysmotility, Genetic myopathies, Whole exome sequencing

Clinical Problem:
An 8-year-old boy presented in November 2024 with abdominal distention, intermittent vomiting and an inability to spontaneously pass stools requiring multiple enemas for 1 month. He had progressive inability to get up from a squatting position starting at 3 years. He was evaluated at another centre for suspected muscular dystrophy and was found to have a creatine phosphokinase (CPK) of 17,000IU/L(normal: 10-120 IU/L). On presentation, his weight was 14 kg (<3^rd percentile according to the Indian Academy of Pediatrics (IAP) charts) and his height was 105 cm (<3^rd percentile according to the IAP charts). On examination, he had pallor, myopathic facies, baggy pant appearance, severe proximal muscle wasting, calf pseudohypertrophy and Gower’s sign was positive. There was upper abdominal fullness. Abdominal ultrasound showed grossly-loaded colon loops. Abdominal contrast-enhanced computerized tomography showed redundant recto-sigmoid colon dilated with fecal loading and mild circumferential thickening of the descending colon. CPK at our centre was 287 IU/L. Nerve conduction studies were suggestive of axonal motor neuropathy of bilateral upper and lower limbs. Electromyography was suggestive of a mixed myopathic-neuropathic pattern. Stool routine showed 80-100 pus cells/high power field and stool culture grew multidrug-resistant Escherichia coli sensitive to carbapenems. Stool Xpert MTB/Rif was negative and stool calprotectin was 5890 g/gm (normal: <50 g/gm). He was treated with intravenous meropenem. Ileocolonoscopy showed a distorted ileocaecal valve, active colitis with pseudopolyps, multiple deep ulcers in the caecum and the entire colon. Colon biopsy showed cryptitis but no crypt abscesses were present. He received oral mesalamine, azathioprine, prednisolone(2 mg/kg/day) and laxatives, to which he symptomatically responded and was discharged on day-20. Whole exome sequencing revealed a likely pathogenic X-linked hemizygous deletion [c.(7098+1_7099-1)_(7309+1_7310-1)del] in the DMD gene at exons 49-50, suggestive of Duchenne muscular dystrophy (DMD). In view of the diagnosis of DMD, he was suspected to have chronic intestinal pseudo-obstruction (CIPO). Steroids were tapered, mesalamine dose was reduced and azathioprine was stopped. He was started on oral rifaximin and probiotics.

What are the gastrointestinal manifestations in DMD and how to treat them?