Wire tethering or 'bowstringing' as a long-term hardware-related complication of deep brain stimulation

Widely reported long-term complications following implantation of deep brain stimulation (DBS) hardware include breakage of electrode leads, internal pulse generator (IPG) failure, skin erosions and infection. Here we report on a rarely described problem that arises from formation of scar tissue adhesions around the DBS extension wire(s). Over time, this scar tissue can become tight and pronounced, protruding noticeably beneath the skin ('bowstringing' in reference to its tight bow-like appearance) and leading to significant limitation of movement and discomfort. We term this 'wire tethering'.

We describe 6 patients with moderate to severe wire tethering. Review of our experience suggests an association of wire tethering with the passage of two extension wires on the same side as is done when using a dual-channel IPG. Five of the patients required surgical revision of the extension wires due to the magnitude of the discomfort, limitation of movement and appearance. Removing the wires was insufficient in the most severe case, necessitating transection of the scar in several places, which was done with the extension wires in situ in 2 patients. Two patients were treated with removal of the wires alone, and 1 patient did not opt for surgery and the tethering has persisted.

Wire tethering, or 'bowstringing', is an underrecognized complication of DBS hardware implantation often necessitating surgical revision. The possible etiology of wire tethering is discussed as well as suggestions for its avoidance.