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Inherited syndrome characterized by microcolon, intestinal hypoperistalsis, dilated small bowel loops and constipation, urinary retention, giant bladder (megacystis), and hydronephrosis.

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Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome (MMIHS); MMIH Syndrome.

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Rare, but a number of MMIHS cases in families of various ethnic backgrounds have been described.

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Mode of transmission is autosomal recessive, with a female predominance of 4:1. Two candidate genes for MMIHS have been located on chromosome 15q24.

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Unknown. Some studies suggest a role of the β-4/α-3 neuronal nicotinic acetylcholine receptor unit. Histologically, the longitudinal smooth muscle fibers of the gut wall are thin with degenerative vacuoles and increased collagen deposits.

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Based on clinical picture and family history.

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Characteristic features of MMIHS are a microcolon with dilated, hypoperistaltic small bowel loops and a large bladder that can be associated with a dilatation of the upper urinary tract. In most cases, the myenteric and submucosal plexus are normal. The abdominal wall might be hypotonic and thin walled, as in prune belly syndrome. One family with MMIHS occurrence in the daughter and isolated prune belly syndrome in the son has been described. One child who died shortly after birth showed cleft palate, severe micrognathia, and a truncus arteriosus communis overriding both ventricles. Another child had multiple cardiac rhabdomyomata at autopsy. Also, one case of MMIHS in trisomy 18 has been reported, but the colon in this child showed aganglionosis. Even with surgery, mortality is high, but some success with intestinal transplantation has been reported.

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Children need a thorough clinical assessment. Although rare, cardiac involvement should be excluded prior to anesthesia.

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Multiple surgical interventions have been reported, but no anesthetic complications were mentioned. Tracheal intubation might be difficult in the presence of cleft palate and micrognathia. Expect a weak cough as a result of abdominal wall hypoplasia. Postoperative mechanical ventilation may be necessary.

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Neuromuscular blockade should be used cautiously and monitored with a peripheral nerve stimulator. Long-term opioid medication should be avoided because of the inhibiting effect on smooth muscles in gut and bladder wall.

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Chronic Idiopathic Intestinal Pseudoobstruction: MMIHS must be differentiated from this milder autosomal dominant form, which can be associated with megacystis but results in only minor symptoms prior to adolescence.

Kohler M, Pease PW, Upadhyay V. Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) in siblings: case report and review of the literature. Europ J Pediatr Surg 14:362, 2004.  [PubMed: 15543490]
Puri P, Shinkai M: Megacystis microcolon intestinal hypoperistalsis syndrome. Semin Pediatr Surg 14:58, 2005.  [PubMed: 15770589]
Rolle U, O'Briain S, Pearl RH, et al: Megacystis-microcolon-intestinal hypoperistalsis syndrome: Evidence of intestinal myopathy. Pediatr Surg Int 18:2, 2002.  [PubMed: 11793054]

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