Implementation of New Technology in Patients with Chronic Deep Brain Stimulation: Switching from Non-Rechargeable Constant Voltage to Rechargeable Constant Current Stimulation

Movement disorder Deep brain stimulation Hybridization: Patient and caregiver outcomes

Background and Objectives

Deep brain stimulation (DBS) is a well-established surgical treatment for certain movement disorders and involves the implantation of brain electrodes connected to implantable pulse generators (IPGs). As more device manufacturers have entered the market, some IPG technology has been designed to be compatible with brain electrodes from other manufacturers, which has facilitated the hybridization of implant technology. The aim of this study was to assess the benefits of hybridization of non-rechargeable, constant voltage IPGs to rechargeable, constant current IPGs.

Methods

A list of DBS movement disorder patients who had their non-rechargeable, constant voltage IPGs replaced with rechargeable, constant current IPGs from a different manufacturer was compiled. Structured surveys of these patients, and their caregivers when applicable, were undertaken to determine both patient and caregiver satisfaction in this DBS hybridization strategy.

Results

Eighteen patients met inclusion criteria and twelve patients or their caregivers completed the structured survey (67% response rate). Nine patients had Parkinson's disease (75%), three had essential tremor (25%). Nine (75%) were converted from bilateral single-channel IPGs, and three (25%) were converted from a unilateral dual-channel IPGs. Overall, 92% of patients and caregivers surveyed reported improvement or no change in their symptoms, 92% reported a decrease or no change in their medication requirements, and 92% report they are satisfied or very satisfied with their IPG hybridization and would recommend the surgery to similar patients. There were no immediate surgical complications.

Conclusion

In this series of movement disorder DBS patients, surgery was safe and patient and caregiver satisfaction were high with a hybridization of non-rechargeable, constant voltage IPGs to rechargeable, constant current IPGs.

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.

Constant current or constant voltage deep brain stimulation: short answers to a long story

PURPOSE

Recently, the feature of generating constant current output has been added to the implantable pulse generators (IPGs). The efficacy of the conventionally used constant voltage (CV) stimulation has been proved in different movement and psychiatric disorders. In this systematic review, we aimed to discuss the effect of constant current (CC) and constant voltage stimulation on patients with Parkinson's disease (PD) who had subthalamic nucleus deep brain stimulation implantation; we also compared these methods of stimulation with each other.

METHODS

Using the words "Deep brain stimulation", "constant current" and "constant voltage", we developed a broad search strategy and a systematic search was conducted in PubMed, Scopus, Web of Science and Cochrane electronic bibliographic databases. Studies on the Parkinson's disease patients with subthalamic deep brain stimulation, which mentioned constant current or/and constant voltage setting stimulation were included.

RESULTS

After screening of 284 articles, 10 reports were found eligible for this study. The score of unified Parkinson's disease rating scale part 3 was improved compared to the baseline, whether the stimulation was CV at baseline or CC. No significant change in non-motor outcomes was found.

CONCLUSIONS

Although CC stimulation has shown a significant improvement in both motor and non-motor symptoms of PD, switching from CV to CC did not result in a significant change in the score of these items based on UPDRS. To sum up, implantation of constant current devices is safe and significantly improves motor function; it also maintains an acceptable safety profile in patients with PD.