Delayed brain and spine migration of a retained SEEG electrode fragment: An unexpected complication

Stereoelectroencephalography (SEEG) is a well-established technique for localizing epileptogenic zones in patients with drug-resistant epilepsy, including children. While considered safe, rare but serious complications can occur.

We report the case of a girl with tuberous sclerosis complex and drug-resistant epilepsy who underwent SEEG implantation as part of pre-surgical evaluation. Electrode placement was uneventful. However, during SEEG monitoring, the signal was lost on two electrodes, raising suspicion of fracture. During explantation, these electrodes were not retrieved, as the distal ends were not visible. The removal of the remaining electrodes proceeded without complication. Nearly 3 years later, the patient developed progressive gait instability. Imaging revealed migration of one electrode fragment into the spinal canal at the L4-L5 level, in contact with the cauda equina, and another fragment into the left temporal horn of the lateral ventricle. The spinal fragment was successfully removed surgically without complication.

To the best of our knowledge, this is the first reported case of brain and spinal migration of a retained fragment of a SEEG electrode. This case highlights a rare but potentially significant complication of SEEG implantation and discuss the management of electrode fragments.