Medical device maker Medtronic sent a letter to surgeons last month advising them to check carefully before implanting the Activa deep-brain stimulation (DBS) device to make sure the wires are not sharply bent or kinked. The company has received reports of wires fracturing.
In the warning letter, Medtronic said it had 16 reports of high impedance measurements that were found to have been caused by wire fractures. The fractures occurred in adaptor wires connected to pocket adaptors for the Activa PC and Activa RC devices, MassDevice reports.
Although the fractures occurred in just a tiny fraction—0.08%—of the roughly 20,000 Activa devices implanted in patients since 2009, the company sent the physician letter to remind surgeons of proper procedures for implanting and using the devices. Fourteen of the 16 affected devices had to be removed. Two wire fractures were discovered during the implantation procedure, Medtronic said.
The risk of wire fractures is similar to a problem Medtronic warned about in April 2015 with its DBS Extensions devices. “To minimize the potential for a conductor wire fracture, please follow the instructions defined within the DBS Pocket Adaptor Implant Manual as shown below, to ensure that the adaptor wire is not bent sharply or kinked at the time of implant. The full implant manual can be found in product packaging,” Medtronic said.
Medtronic’s DBS devices are used for patients with Parkinson’s disease or Essential Tremor, to help control tremor in patients whose tremor in not adequately controlled by medications and where the tremor constitutes a “significant functional disability.” Deep brain stimulation is also used to “aid in the management of chronic, intractable (drug refractory) primary dystonia.” Dystonia is a movement disorder in which the muscles contract involuntarily, causing repetitive or twisting movements. The muscle spasms can be mild or severe, and might interfere with day-to-day tasks. Surgery is sometimes used to disable or regulate nerves or certain brain regions in people with severe dystonia, the Mayo Clinic explains.
In the product manual, Medtronic warns against abruptly stopping stimulation because the patient may experience a return of symptoms, in some cases at greater intensity than before the implant. Adverse events related to the therapy, the device, or the procedure can include: stimulation not effective, cognitive disorders, pain, dyskinesia, dystonia, speech disorders, infection, intracranial hemorrhage, electromagnetic interference, cardiovascular events, visual disturbances, sensory disturbances, device migration, abnormal gait, headaches, repositioning, abnormal thinking, lead fracture, seizures, respiratory events, and shocking or jolting stimulation. Patients using a rechargeable neurostimulator for Parkinson’s disease or Essential Tremor should check for skin irritation or redness near the neurostimulator during or after recharging, and contact their physician if symptoms persist.