Post traumatic tremor and thalamic deep brain stimulation: evidence for use of Diffusion Tensor Imaging.
Boccard SG., Rebelo P., Cheeran B., Green A., FitzGerald JJ., Aziz TZ.
BACKGROUND: Deep Brain Stimulation (DBS) is a well-established treatment to reduce tremor, notably in Parkinson Disease. DBS may also be effective in posttraumatic tremor, one of the most common movement disorders caused by head injury. However, these cohorts of patients often have multiple lesions that may impact the outcome depending on which fibre tracts are affected. CASE DESCRIPTION: A 20-year-old man presented after road traffic accident with severe closed head injury and polytrauma. CT-scan showed left frontal and basal ganglia haemorrhagic contusions and intraventricular haemorrhage. A disabling tremor evolved in step with motor recovery. Despite high intensity signals in the intended thalamic target, a visual analysis of the pre-operative Diffusion Tensor Imaging revealed preservation of connectivity of the intended target, VOP. This was confirmed by the post-operative tractography study presented here. DBS of the ventralis oralis posterior thalamic nucleus- zona incerta VOP/ZI was performed. Six months post implant, marked improvement of action (postural, kinetic and intention) tremor was achieved. CONCLUSIONS: We demonstrated a strong connectivity between the (VOP) and the superior frontal gyrus containing the premotor cortex and other central brain areas responsible for movement control. In spite of an existing lesion in the target, the preservation of these tracts may be relevant to the improvement of the patient's symptoms by DBS.