Objective: Deep brain stimulation (DBS) is a FDA approved treatment for dystonia. Medtronic pulse generator (IPG), constant voltage (CV) stimulation and Boston Scientific generator, constant current (CC) stimulation are two types of DBS which are approved. We encountered a patient who had dystonic storm when CV stimulation was changed to CC stimulation and resolved upon changing back to CV stimulation.

Background: We present an interesting patient with dystonia who was well controlled with CV stimulation and then substantially worsened when it was changed to CC stimulation, despite multiple programming attempts. Her symptoms were rapidly controlled when the device was replaced back to a CV stimulation device.

Method: 26-year-old woman with a history of generalized dystonic features since age 7. She presented with difficulty with walking and gradually progressed with speech involvement. By the age of 20, her breathing was also affected. Her brother, 20 years old, has a similar history of dystonia since age 8 including progression of symptoms without hyperkinetic features. They underwent bilateral GPi DBS (Medtronic PC) and improved clinically. The clinical improvement was stable for over 4 years. In 2015, 2016 and 2017, IPG was replaced with a CV device without the need for reprogramming.  In 2018, on the same day, the IPGs were replaced from Medtronic to Boston Scientific (CV to CC stimulation). Within hours of the replacement, the sister had worsening of dystonic symptoms with dysphagia, speech difficulty and difficulty with walking. On examination she had facial, laryngeal, cervical and truncal dystonia.

Results: Multiple factors were taken into consideration during troubleshooting and reprogramming, including impedance check, proper laterality of lead extensions, and programming of stimulation parameters identical to the previous settings. No errors were found and after 10 days of no clinical improvement, the decision was made to replace the device back to her original Medtronic IPG model and stimulation parameters. The day after surgery, her dystonia was well controlled back to her baseline. No errors in CC stimulation IPG were found. Interestingly, her brother did not have any worsening of symptoms with changing from CV to CC stimulation.

Conclusion: In our case, it is not clear of why changing from CV to CC stimulation had such an impact on her symptoms, but we felt it is important to communicate the experience.

References: 1. Ramirez de Noriega F, Eitan R, Marmor O, Lavi A, Linetzky E, Bergman H, Israel Z. Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson’s Disease. Stereotact Funct Neurosurg. 2015 Feb 18;93(2):114-121. 2. Allert N, Kirsch H, Weirich W, Karbe H. Stability of symptom control after replacement of impulse generators for deep brain stimulation. J Neurosurg 110: 1274-1277, 2009.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dystonic-storm-with-a-change-of-stimulation-from-constant-voltage-to-constant-current/