Deep brain stimulation of the dentato-rubro-thalamic tract in a case of Holmes tremor: a constrained spherical deconvolution (CSD)-guided procedure

Deep brain stimulation (DBS) is an established treatment for movement disorders, including Holmes tremor (HT). HT is a rest and action tremor that occurs as a late symptom of brainstem lesions such as stroke. Unfortunately, it is frequently refractory to medical treatment, hence DBS surgery may be a good option. Due to variable results, the ideal target for DBS in HT still remains to be established, ranging from the thalamus to the globus pallidus internus, to the subthalamic nucleus. Pre-operative imaging also is very challenging, as the complexity of brain fiber architecture may prevent the correct positioning of the directional lead. Herein, we describe the case of a patient affected by a rubral tremor secondary to a brain hemorrhage, who had advanced pre-operative neuroimaging with constrained spherical deconvolution (CSD)-based tractography obtained from diffusion-weighted imaging (DWI) to identify the dentato-rubro-thalamic tract, involved in the pathophysiology of HT. The patient was then addressed to an awake DBS surgery, and with the help of intraoperative microelectrode recordings, a tailored DRTT-targeted procedure was performed. The stimulation determined an almost complete tremor suppression, with no significant side effects at a follow-up of 6 months, paving the way towards new effective techniques for the planning, i.e., CSD-based tractography and the treatment of refractory tremors.