Perimesencephalic cistern obliteration: a CT sign of life-threatening shunt failure.

Death from cerebrospinal fluid shunt malfunction is a rare but tragic event. The authors describe seven children who when admitted were lethargic but arousable because of shunt failure. Sudden deterioration prompted unscheduled emergency shunt revision in each case. Two children subsequently died. Although neither the history nor the physical findings predicted this life-threatening shunt malfunction, obliteration of the perimesencephalic cistern was apparent on all preoperative computerized tomography (CT) scans. For reference, the scans of 43 other hydrocephalic children were drawn randomly from the hospital files and analyzed. It is concluded that CT evidence of obliteration of the perimesencephalic cistern is a useful warning of life-threatening shunt failure.