Malfunction of SynchroMed II baclofen pump delivers a near-lethal baclofen overdose

Intrathecal baclofen therapy using implantable pumps is an established treatment for spasticity. The pumps occasionally experience serious malfunction.

A 12-year-old girl suffering from spastic diplegia was implanted with a Medtronic SynchroMed II pump (Medtronic Inc., Minneapolis, Minn., USA). During a refill at 3 months 19 ml of baclofen were still in the pump. It was assumed that there was a lumbar catheter obstruction and a revision was performed. At 11 months she was receiving 180 microg/day. When she presented for refill, there were again 19 ml of baclofen in the reservoir. The pump was refilled, stopped and restarted at a lower dose. Ten minutes after restart the patient was complaining that she could not move her legs. Within the next 50 min she lapsed into coma, from a presumed baclofen overdose. She was intubated and ventilated. The reservoir was emptied of baclofen and the pump stopped. Seventeen hours after the baclofen overdose, the patient woke up gradually with no new neurological deficits. The pump was removed a week later. Medtronic laboratories examined the pump and reported no technical fault.

The implanted Medtronic SynchroMed II pump suffered an unusual malfunction. It is postulated that the pump had suffered a motor stall, and when it was restarted, it gave an unusually high, potentially lethal, dose to the patient.

Physicians who implant pumps for intrathecal baclofen administration need to be aware that these devices may suffer unheralded catastrophic failure that can lead to potentially lethal overdose administration.