Enteric Neuromuscular Manifestations in Neurofibromatosis Type I

Several genetic syndromes that affect nerve development and functioning may involve the enteric nervous system and present clinically as dysmotility syndromes, typically in childhood.

To review the enteric neuromuscular manifestations, predominantly observed in adults, of neurofibromatosis type I at a tertiary referral center.

We conducted a medical records review at the Mayo Clinic and documented clinical manifestations and findings on radiology, pathology, and specialized motility tests of the esophagus, stomach, colon, and rectal evacuatory functions. The tests included scintigraphic gastrointestinal and colonic transit measurements, intraluminal esophageal, gastrointestinal, colonic, and anorectal manometry, and balloon expulsion test.

Among 2406 with documented NF1, the gastrointestinal manifestations were obstruction or dysmotility, seen in 2% of the cohort. Thirteen patients had small bowel or colonic obstructions: 4 gastrointestinal stromal tumors, 3 malignant peripheral nerve sheath tumors, 3 neurofibromas, 1 diffuse ganglioneuromatosis, 1 schwannoma, and 1 inflammatory fibroid polyp. In addition, 38 patients had abnormal gut motility, including esophageal achalasia or spasm, delayed gastric emptying, slow colonic transit, and dyssynergic defecation. Gastric, small bowel, and colonic manometry were characterized by normal amplitude incoordinated contractions suggestive of neuropathy. In the few resected specimens, myenteric plexus proliferation or diffuse ganglioneuromatosis was identified histologically.

In addition to mechanical obstruction, typically due to benign tumors affecting smooth muscle or components of nerve (sheath or nerve fiber), patients with NF1 may present with dysmotility syndromes such as gastroparesis, slow colonic transit, or global dysmotility. Neuropathic dysmotility in NF1 can be identified by manometry and by histological evidence of myenteric plexus proliferation or diffuse ganglioneuromatosis.