Sudden loss of the deep brain stimulation effect with high impedance without macroscopic fracture: a case report and review of the published literature

Pediatric Deep Brain Stimulation for Dystonia: Current State and Ethical Considerations

Dystonia is a movement disorder that can have a debilitating impact on motor functions and quality of life. There are 250,000 cases in the United States, most with childhood onset. Due to the limited effectiveness and side effects of available treatments, pediatric deep brain stimulation (pDBS) has emerged as an intervention for refractory dystonia. However, there is limited clinical and neuroethics research in this area of clinical practice. This paper examines whether it is ethically justified to offer pDBS to children with refractory dystonia. Given the favorable risk-benefit profile, it is concluded that offering pDBS is ethically justified for certain etiologies of dystonia, but it is less clear for others. In addition, various ethical and policy concerns are discussed, which need to be addressed to optimize the practice of offering pDBS for dystonia. Strategies are proposed to help address these concerns as pDBS continues to expand.

DBS dysfunction mimicking transient ischemic attacks-a case report

We report on a patient with thalamic deep brain stimulation (DBS) for essential tremor who was admitted to a stroke unit with transient vertigo, dysarthria, and gait disturbance. Transient ischemic attacks were assumed but fluctuating neurological symptoms persisted until presentation to a DBS center. Here, unstable high monopolar impedances of the right-hemispheric electrode contacts were detected. Surgical revision revealed a fracture of the pocket adaptor connecting this electrode to the impulse generator. Replacement resulted in stable impedances and remitted the transient neurological symptoms. Emergency and stroke doctors should be aware of neurological symptoms induced by technical dysfunctions in DBS.

Management of Elevated Therapeutic Impedances on Deep Brain Stimulation Leads

CLINICAL VIGNETTE

A 64-year-old male with a history of essential tremor with bilateral thalamic ventralis intermedius deep brain stimulation implants had elevated therapeutic impedance values despite normal lead integrity impedances and good response to stimulation.

CLINICAL DILEMMA

Do elevated therapeutic impedance values indicate a sign of hardware malfunction? What are the guidelines to approach deep brain stimulation hardware malfunction?

CLINICAL SOLUTION

Lead integrity impedance values are a better evaluation of hardware integrity. The discrepancy between therapeutic and lead-integrity impedance values can arise when using low voltage settings.

GAPS IN KNOWLEDGE

There are no established guidelines for the management of possible hardware malfunction in deep brain stimulation. The recommended approach is to distinguish between open and short circuit problems followed by an "inching" evaluation, assessing the structures from the implantable and programmable generator to the intracranial leads. Constant-current devices will deliver a more stable stimulation but the effect of their adoption is still not clear.

EXPERT COMMENTARY

This case emphasizes the need for clinicians to understand fundamental differences in lead integrity and therapeutic impedance while utilizing a methodical approach in treating hardware malfunction. It highlights future avenues of investigation regarding the utility of constant current DBS technology.

Rapid battery depletion and loss of therapy due to a short circuit in bipolar DBS for essential tremor

Technical dysfunctions have been reported reducing efficacy of deep brain stimulation (DBS). Here, we report on an essential-tremor patient in whom a short circuit in bipolar DBS resulted not only in unilateral loss of therapy but also in high current flow and thereby rapid decline of the impulse-generator battery voltage from 2.83 V a week before the event to 2.54 V, indicating the need for an impulse-generator replacement. Immediate re-programming restored therapeutic efficacy. Moreover, the reduction in current flow allowed the battery voltage to recover without immediate surgical intervention to 2.81 V a week later.