The Safety to Switch from Constant Voltage to Constant Current with a Mixed Internal Pulse Generator in Deep Brain Stimulation

BACKGROUND: Deep brain stimulation (DBS) is an efficient modality for the treatment of movement disorders. Differing from the constant voltage (CV)-DBS devices, constant current (CC)-DBS devices may allow more precise stimulation of the target brain regions since they are less influenced by impedance. If internal pulse generators (IPGs) of DBS devices are required to be connected with electrodes of different brands, employing proper adapters is necessary. Such connected DBS devices are called mixed or hybrid devices. OBJECTIVES: As there is sparse information about the clinical mixed devices, we studied their safety and efficacy. MATERIALS AND METHODS: Clinical scores of 13 patients implanted with mixed DBS devices were determined with the Unified Parkinson’s Disease Rating Scale (UPDRS) in Parkinson’s disease (PD) (n = 10) and with the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS) in dystonia (n = 3). Patient satisfaction was assessed with the Timmerman questionnaire. The Clinical Global Impression Improvement (CGI-I) Scale was also evaluated. RESULTS: Patients’ overall satisfaction was considerably higher with mixed devices. The UPDRS and BFMDRS clinical scores did not significantly differ after switching to a mixed DBS device. Three patients before the DBS switch suffered from side effects under the CV mode. These patients got rid of the side effects in their follow-up with a reduction in pulse width values. DISCUSSION: Mixed devices working in CC mode are well tolerated with high patient satisfaction. CONCLUSION: Besides patient satisfaction, mixed IPGs are also considered safe.