Safety of transcranial direct current stimulation in a patient with deep brain stimulation electrodes

Abstract

Background: Transcranial direct current stimulation (tDCS) has been investigated in movement disorders, making it a therapeutic alternative in clinical settings. However, there is still no consensus on the most appropriate treatment protocols in most cases, and the presence of deep brain stimulation (DBS) electrodes has been regarded as a contraindication to the procedure. We recently studied the effects of cerebellar tDCS on a female patient already undergoing subthalamic nucleus deep brain stimulation (STN-DBS) for generalized dystonia. She also presented with chronic pain and depression. With STN-DBS, there was improvement of dystonia, and botulinum toxin significantly reduced pain. However, depressive symptoms were worse after STN-DBS surgery. Methods: Neuromodulation with 2 mA anodal cerebellar tDCS was initiated, targeting both hemispheres in each daily 30 minute session: 15 minutes of left cerebellar stimulation followed by 15 minutes of right cerebellar stimulation. The DBS electrodes were in place and functional, but the current was turned off during tDCS. Results: Although our goal was to improve dystonic movements, after 10 tDCS sessions there was also improvement in mood with normalization of Beck Depression Inventory scores. There were no complications in spite of the implanted STN-DBS leads. Conclusion: Our results indicate that tDCS is safe in patients with DBS electrodes and may be an effective add-on neuromodulatory tool in the treatment of potential DBS partial efficacy in patients with movement disorders.

Safety of Non-invasive Brain Stimulation in Patients with Implants: A Computational Study

“…The same is true for a case study in a single female patient with implanted DBS electrodes, where tDCS was used as an adjuvant therapy for the treatment of generalized dystonia and proved to be well tolerated [18]. In addition to limited sample size, the absence of long-term follow-up data prevents assessment of sustained effects and potential risks associated with such a combination therapy [18]. Comparisons of various tDCS montages, both with intact skulls and simulated burr holes, indicated little effect on peak current density and E-fields, suggesting that the presence of a DBS lead might not significantly alter brain current flow under realistic conditions when the burrhole defect is fluid-filled and relatively conductive [19].…”

“…However, only a small sample size (two patients) was considered and no systematic investigation was performed, which limits the generalizability of the findings. The same is true for a case study in a single female patient with implanted DBS electrodes, where tDCS was used as an adjuvant therapy for the treatment of generalized dystonia and proved to be well tolerated [18]. In addition to limited sample size, the absence of long-term follow-up data prevents assessment of sustained effects and potential risks associated with such a combination therapy [18].…”

Limited output transcranial electrical stimulation 2023 (LOTES-2023): Updates on engineering principles, regulatory statutes, and industry standards for wellness, over-the-counter, or prescription devices with low risk

“…Statements that are 1) sufficiently vague as to confound implementation; 2) lack evidence-base for risk (see above); and/or 3) contrast with existing use-cases are removed. For example, warnings/precautions regarding implants can be ambiguous regarding what types of devices qualify (e.g., dental implants), are not supported by evidence for risk, and contradict with use-cases of stimulation with intracranial implants [ 39 – 43 ] or pacemakers [ 44 ]. There is also evidence for the use of electroconvulsive therapy (ECT), which involves intensities above (~400x; [ 45 , 46 ]) those relevant for this limited-output guidance, with implants without injury [ 47 – 49 ].…”

Safety of Transcranial Direct Current Stimulation in Neurorehabilitation

“…Since tDCS applies electricity to the human body artificially, in principle, it should not be conducted when an electrical device is implanted in the body. However, Iannone et al [ 34 ] conducted 15 sessions of 30-minute cerebellar tDCS at 2 mA intensity with a 35 cm 2 electrode in patients who had deep brain stimulators (DBSs) in the subthalamic nucleus for the treatment of generalized dystonia. The DBSs were turned off while tDCS stimulation was delivered.…”