Ventralis intermedius plus ventralis oralis anterior and posterior deep brain stimulation for posttraumatic Holmes tremor: two leads may be better than one: technical note.

OBJECTIVE AND IMPORTANCE

To describe the effects of ventralis oralis anterior (VOA) and posterior (VOP), as well as ventralis intermedius (VIM), deep brain stimulation (two ipsilateral thalamic leads implanted) on posttraumatic Holmes tremor. Results of both thalamic lesioning and thalamic deep brain stimulation for Holmes tremor and tremors due to posttraumatic lesions in the region of the midbrain have been disappointing. In 2001, the use of two electrodes implanted in parallel for severe essential tremor was reported. We propose the use of a similar technique for posttraumatic Holmes tremor. One rationalization for the placement of two leads was to affect both the cerebellar receiving area (VIM) and the pallidal receiving area (VOA/VOP). A second rationalization was that the placement of a second electrode may affect somatotopy, and may, therefore, be beneficial for the treatment of more difficult to control tremor subtypes.

CLINICAL PRESENTATION

A 24-year-old man with intractable posttraumatic Holmes tremor presented for consideration of a surgical intervention.

INTERVENTION

A high-resolution, volumetric magnetic resonance imaging scan was obtained 1 day before the procedure. Microelectrode recording was used in addition to stereotactic computed tomography, image fusion, and stereotactic targeting to map the locations of the VIM, VOP, and VOA nuclei of the thalamus. A deep brain stimulation electrode was then implanted on the border between the left VIM and VOP thalamic nuclei, and a second ipsilateral deep brain stimulation lead was placed on the VOA and VOP border, 2 mm anterior to the first. Fourteen videotaped tremor rating scales were evaluated by two blinded reviewers.

CONCLUSION

The patient experienced tremor rebound with VIM-VOP monotherapy. However, when the second lead (VOA/VOP) was activated, he experienced sustained improvement in tremor and tremor disability at a 12-month follow-up examination. This case elucidates a potential new approach for the treatment of patients with posttraumatic Holmes tremor. Additional study and longer follow-up periods will be needed to further evaluate this promising therapy.