In an October 2016 “Urgent Field Safety Notice”, Medtronic warned that some rechargers for its deep brain stimulation devices may be prone to an “error state” and fail to charge. According to the letter, some of its Model 37751 rechargers may become unresponsive and fail to recharge the neurostimulator until they are reset. The company has received reports of the chargers malfunctioning, where they bleep every five seconds while displaying a blank screen.
According to the letter, the “error state” occurs in 2 percent of rechargers manufactured after November 2014 and 0.2 percent of rechargers manufactured before that date. The serial numbers on rechargers manufactured November 2014 and later begin with “NKA4” or “NKU4”.
Until the rechargers are reset, they are unable to recharge the neurostimulator while in error state. Deep brain stimulation devices are used for various neurological disorders. For example, they are used for movement symptoms related to Parkinson’s disease and epilepsy.
If the battery is depleted, the deep brain stimulation devices will no longer deliver therapy. If this occurs, patients may experience neurological symptoms once again. In some instances, the loss of neurostimulation can lead to life-threatening injury or death. Examples include akinetic crisis, the severe inability to move, with Parkinson’s patients and status epilepticus in epilepsy patients. Status epilepticus is when a seizure lasts for too long or seizures follow one another without recovery. There have been no reports of life-threatening injury or death so far.
To prevent the error from occurring, Medtronic says rechargers should be plugged into the AC power supply before recharging and should remain connected until the charging is complete. Healthcare professionals can help patients reset the recharger if it is already unresponsive. The letter says physicians should notify their patients of the recharger issue and discuss how to address the problem.