Adaptive deep brain stimulation for Parkinson's disease demonstrates reduced speech side effects compared to conventional stimulation in the acute setting
Deep brain stimulation (DBS) for Parkinson's disease (PD) is currently limited by costs, partial efficacy and surgical and stimulation related side effects. This has motivated the development of adaptive DBS (aDBS) whereby stimulation is automatically adjusted according to a neurophysiological biomarker of clinical state, such as b oscillatory activity (12 30 Hz) aDBS has been studied in parkinsonian primates and patients and has been reported to be more energy efficient and effective in alleviating motor symptoms than conventional DBS (cDBS) at matched amplitudes.1 ,2 However, these studies have not considered whether side effects can also be avoided with clinically effective stimulation. In PD, it is well recognised that a significant proportion of patients develop speech deterioration following DBS of the subthalamic nucleus (STN) which may be reversible.3 Here we test bilateral stimulation, optimising parameters for aDBS, and evaluate speech intelligibility. We hypothesised that acute aDBS would be more effective and more efficient than cDBS at matched stimulation parameters while causing less speech impairment. We recruited 10 patients with advanced idiopathic PD following implantation of DBS electrodes into the STN.2 Recordings took place 3 6 days following electrode placement during a temporary period of externalisation. All participants gave informed written consent, and were tested following overnight withdrawal of dopaminergic medication (see online supplementary material) Two patients were excluded due to external stimulator failure leading to no voltage delivery under aDBS and cDBS conditions. supplementary data [jnnp 2016 313518supp.pdf] aDBS stimulation was delivered bilaterally, only when b amplitude exceeded a threshold as previously described.2 aDBS contacts, voltages and trigger thresholds were independently set for the two sides according to motor benefit versus induced paraesthesiae, with the same contacts/voltages used for cDBS. Stimulation in each block continued for 15 min prior to evaluation. Participants were assessed
Journal of Neurology, Neurosurgery Psychiatry