Clinical and Programming Pattern of Patients with Impending Deep Brain Stimulation Power Failure: a Retrospective Chart Review

Background: It is important to prevent complications of implanted pulse generators (IPG) depletion by replacing the IPG in time.

Methods: We reviewed the charts of all patients with deep brain stimulation treated movement disorders who were seen at our institution over a period of 6 months. Among these, we retained for analyses those who had undergone IPG replacement within the previous 3 years.

Results: A total of 55 IPG replacements (from 38 patients) were reviewed. Electrodes were implanted in the subthalamic nucleus in all Parkinson's disease patients, in the ventral intermedius nucleus of the thalamus in all essential tremor patients and in the globus pallidus interna in all dystonia patients. Replacements were preceded by a voltage increase due to worsened symptoms in 27.3% (15/55); 25.5% (14/55) had full IPG depletion or had too low IPG reserve to allow for any voltage adjustment; and 21.7% (12/55) did not get a needed voltage increase either for safety reasons (eg: concern for increase in falls with higher voltages) or because the surgery date for IPG replacement was close. Only 25.5% (14/55) remained clinically well-controlled prior to IPG replacement, all of whom had IPG longevity estimates available. Clinical deterioration was noted prior to IPG replacement in 100% of patients without available longevity estimates versus 61% of patients with available longevity estimates (p < 0.001).

Conclusion: Despite best efforts, clinical deterioration prior to IPG replacement can be seen frequently. Routine estimation of IPG life, along with symptom assessment at every follow-up visit may prevent it.