Conflicting Signals: A Case Report of Recurrent Intrathecal Baclofen Pump Stalls Triggered by a Vagus Nerve Stimulator Magnet

Case Diagnosis: A patient with a medical history of traumatic brain injury (TBI)-associated spasticity and seizures experienced multiple intrathecal baclofen (ITB) pump stalls caused by interference from a vagus nerve stimulator (VNS) magnet.

Case Description or Program Description: A 49-year-old male with a history of TBI secondary to a motor vehicle accident had an ITB pump implanted in 2006 for left spastic hemiparesis, which was replaced in 2013 and 2020. In 2018, he received a VNS for TBI-associated seizures. He presented to our rehabilitation clinic in September 2024 for ITB pump management. Interrogation of the pump revealed multiple motor stall events in the event log. The patient reported wearing a magnet on a wristband to activate his VNS.

Setting: Outpatient neurorehabilitation clinic.

Assessment/Results: When at rest, the patient’s arm naturally fell over his ITB pump. To mitigate interference, staff relocated the magnet wristband to a key lanyard around his neck, ensuring it remained away from the pump. He was advised to keep the VNS magnet approximately 6 inches away from his pump and was educated on recognizing and responding to critical pump alarms to prevent withdrawal. On his next visit, the number of motor stall events had decreased.

Discussion (relevance): It is well known that ITB pumps are susceptible to magnetic fields such as magnetic resonance imaging (MRI), which can temporarily stall the pump rotor. While there are case reports of personal laptops and smartphones causing similar complications, this appears to be the first documented case of recurrent ITB pump stalls caused by a VNS magnet.

Conclusions: A VNS magnet can generate a magnetic field capable of stalling an ITB pump rotor. Although rare, this complication is potentially serious, and patients with both devices should be informed of this risk.