Severe constipation: an under-appreciated cause of VP shunt malfunction: a case-based update.

BACKGROUND: Increased intra-abdominal pressure has been reported to result in raised intracranial pressure in a variety of conditions such as obesity and pregnancy, and it also constitutes an infrequent cause of ventriculoperitoneal (VP) shunt malfunction. Patients with neurological deficits, as those with myelomeningocele or cerebral palsy, are prone to developing a neurogenic bowel and to suffer chronic constipation. Although previously recognized, VP shunt failure attributed to constipation has only recently been described. We briefly review the etiopathogenesis, diagnosis and management of severe constipation leading to VP shunt malfunction. Our aim is to draw the attention of pediatric neurosurgeons towards severe constipation as a possible cause of VP shunt failure thus avoiding unnecessary surgical valve revisions, to which children with hydrocephalus are often submitted to. ILLUSTRATIVE CASES: We report two children that developed transient VP shunt failure because of intense constipation that caused exacerbation of previously shunted hydrocephalus. One of the patients constitutes the first description of this complication associated with an anteriorly placed anus and the other with intestinal paresis after ileostomy. Conservative treatment aimed at alleviating the increased intra-abdominal pressure resulted in complete resolution of the children's manifestations of VP shunt failure, without having to resort to surgical revision of the VP shunt.