Failed DBS for palliation of visual problems in a case of oculopalatal tremor

ObjectiveTo report the results of attempted bilateral red nucleus (RN) deep brain stimulation (DBS) for the palliative treatment of visual problems associated with oculopalatal tremor (OPT).BackgroundIt is hypothesized that OPT results from a defect in the Guillain–Mollaret triangle, a circuit that includes connections with the dentate nucleus, the contralateral red nucleus, and the inferior olive. We present a high functioning patient (an accountant) who underwent a palliative trial of RN region DBS in an approach targeted through the subthalamic nucleus region. The aim was to reduce eye tremor and improve vision through interruption of the pathologically oscillating circuit in the Guillain–Mollaret triangle.MethodsFollowing informed consent, a patient with OPT (and failure of multiple classes of medication and botulinum toxin therapy) underwent placement of bilateral DBS electrodes within the region of the RN. He underwent preoperative testing and testing after 12 months of continuous stimulation with the device in monopolar, bipolar, low frequency, and high frequency settings.ResultsThe patient did not demonstrate significant changes in the neurological examination following the procedure and postoperative programming sessions. Eye tremor was monitored pre- and postoperatively by ocular EMG and did not change in frequency. Following the one-year trial, stimulation was discontinued as there were no improvements in vision.ConclusionDBS for OPT was not clinically effective. There were many potential reasons for failed efficacy including a failure to implant the electrodes deep and medial enough into the target region because of stimulation induced side effects. Other targets within the Guillain–Mollaret circuit (and outside of the circuit) may be more useful, though they may prove to be less safe and even more difficult to access. Better custom designed DBS leads may be needed for such small targets in critical brain regions.