Respiratory depression during VP shunting in Arnold Chiari malformation Type-II, a rare complication (Case reports and review of literature)

The VP Shunt is a common pediatric surgical procedure in our country. Hydrocephalus is commonly associated with meningomyelocele in Arnold Chiari malformation-II and the ventriculoperitoneal shunt insertion is the common surgical procedure for the management of hydrocephalus. The standard protocol is to rule out any hydrocephalus by preoperative MRI. If associated with hydrocephalus, insertion of the VP shunt is indicated before the repair of MMC whereas the absence of hydrocephalus indicates that the surgical repair of MMC is to be undertaken immediately. Anesthetic management of the patient during the insertion of ventriculoperitoneal shunt may pose problems. We report here two cases of ACM-II (lumbar MMC with associated hydrocephalus) who had respiratory depression / delayed emergence after an otherwise uneventful procedure. Although the VP shunt (first procedure) required postoperative ventilation which improved later, the phenomena of respiratory depression / delayed emergence did not occur after the MMC repair (second surgery). The possible mechanisms involved in these events and their various clinical aspects are discussed below.