The Biological Fate of DBS Leads After 15 Years of Stimulation

Deep brain stimulation (DBS) has been shown to provide benefits for dystonia beyond 15 years. However, the long-term biological response to chronically implanted DBS hardware and its structural integrity over such extended periods remain poorly characterized. Pathological examination of explanted leads and especially those implanted for over a decade or more has been rarely performed.

The aim was to document the pathological findings of bilaterally explanted globus pallidus pars interna (GPi) DBS leads after 15 years of continuous therapy in a patient with DYT-1 dystonia.

We present the case of a 23-year-old woman with genetically confirmed DYT-1 dystonia who underwent bilateral GPi DBS implantation at the age of 8. After 15 years of stable therapeutic benefit, she experienced progressive functional decline despite extensive reprogramming attempts. Bilateral lead revision was performed, and the explanted DBS leads were examined macroscopically and microscopically.

The explanted leads demonstrated striking macroscopic abnormalities, including membrane coating and mild contact degradation. Microscopic examination revealed extensive fibrous tissue encapsulation and adherent coagulated brain tissue, suggestive of a mild chronic foreign body response. The left DBS lead revealed a decreased electrical impedance, and this was correlated with contact degradation. Despite lead revision, no definitive symptom improvement occurred after 9 months.

These findings suggest that DBS leads may maintain therapeutic function despite significant biological and structural changes over a 15-year period. Hardware integrity in this case did not correlate with clinical effectiveness.