EVIDENCE FOR A PATENT FIBROUS TRACT IN FRACTURED, OUTGROWN, OR DISCONNECTED VENTRICULOPERITONEAL SHUNTS

As cerebrospinal fluid (CSF) shunts function for several years, outgro wth and disconnection of the distal catheter are seen more frequently. Though a shunt revision is clearly indicated if patients are symptoma tic, asymptomatic patients with a disconnection or who have outgrown t he distal catheter may no longer require CSF diversion. This follows a n assumption that the shunt is no longer functioning and, in an asympt omatic patient, no longer required. However, patent fibrous tracts hav e been postulated which may allow passage of CSF through disconnected or outgrown distal catheters. We have recently treated 2 patients with ventriculoperitoneal (VP) shunts with evidence of a persistent fibrou s tract. A 13-year-old boy was asymptomatic for 2 years after radiogra phs revealed an outgrown distal VP shunt catheter, after which he acut ely deteriorated and died from massive hydrocephalus, although the ent ire shunt was patent. Another 14-year-old boy who was profoundly retar ded presented with subtle changes in his daily activity. Shunt radiogr aphs revealed two disconnections and a broken valve, but a shunt tap r evealed a normal opening pressure (OF). A radionuclide shuntogram reve aled rapid passage of isotope through fibrous sheaths at the disconnec tions, and into the peritoneum. A shunt revision was performed and the patient returned to his previous level of health. Patients with outgr own or disconnected distal catheters may be asymptomatic and/or have n ormal OF, and must not be assumed to have arrested hydrocephalus. A ve ntricular pressure measurement and radionuclide shuntogram should be p erformed to rule out a patent persistent fibrous tract.