Subthalamic nucleus stimulation-induced local field potential changes in dystonia

BACKGROUND: Subthalamic (STN) stimulation is an effective treatment for Parkinson’s disease and induced local field potential (LFP) changes that have been linked with clinical improvement. Subthalamic stimulation has also been used in dystonia although the internal globus pallidus is the standard target where theta power has been suggested as a physiomarker for adaptive stimulation. OBJECTIVE: We aimed to explore if enhanced theta power was also present in STN and if stimulation-induced spectral changes that were previously reported for Parkinson’s disease would occur in dystonia. METHODS: We recorded LFPs from seven patients (twelve hemispheres) with isolated craniocervical dystonia whose electrodes were placed such that inferior, middle and superior contacts covered STN, Zona incerta and thalamus. RESULTS: We did not observe prominent theta power in STN at rest. Subthalamic stimulation induced similar spectral changes in dystonia as in Parkinson’s disease such as broadband power suppression, evoked resonant neural activity, finely-tuned gamma oscillations and a rise of aperiodic exponents in STN-LFPs. Both power suppression and evoked resonant neural activity localise to STN. Accordingly, single pulse subthalamic stimulation elicits evoked neural activities with largest amplitudes in STN, which are relayed to Zona incerta and thalamus with changing characteristics as the distance from STN increases. CONCLUSIONS: Our results show that subthalamic stimulation-induced spectral changes are a non-disease-specific response to high-frequency stimulation, which can serve as placement markers for STN. This broadens the scope of subthalamic stimulation and makes it an option for other disorders with excessive oscillatory peaks in STN.