Objective: Is our aim to present our experience with bilateral directional thalamic DBS for DT.

Background: Dystonic tremor(DT) is characterized by coexisting tremor and abnormal dystonic posturing in the same body segment. DT is often medically refractory and deep brain stimulation (DBS) is a valid therapeutic option. However, the optimal surgical target remains uncertain with Vim, GPi, Vop and PSA/zona incerta reported as effective. The severity of the dystonia may alter the thinking about optimal targeting.

Method: A 27-year-old female with DT presents in our Unit of Functional Neurosurgery for evaluation of DBS candidacy. Examination revealed subtle dystonic features as well as a disabling postural-action bilateral upper limb tremor. Her brain and cervical spine MRI were both normal. Neurophysiological test showed dystonic and rhythmic bursts of EMG at 5Hz on both upper arms. There was no improvement upon treatment with L-dopa. The patient was bilaterally implanted with directional leads Vercise Gevia™, (Boston Scientific) in the thalamus, with the aim to stimulate both nucleus; Vim and Vop in July 2018. She underwent an extended programming session of her DBS system 6 days post-surgery. The programming session followed the procedure of a standard monopolar review, in which for each electrode configuration current thresholds were determined for complete tremor control and the first adverse event limiting further current increase. At 3 months follow up dorsal contacts were added, adjusting the stimulation parameters with the aim of targeting Vop and to improve dystonic features.

Results: The current programming settings(6m FU) are for left Vim/Vop: 2-,3-,4-(30-30-30%)and 5-6-(7,3%);3,2mAmp, 60usec, 130Hz and right Vim/Vop; 10-(90%)and 13-,14-(5,5%) 2.7mAmp, 60usec, 130Hz. At 6mFU she had an improvement of 33-50 and 17,6% in CRST (part A-B and C).And she has started to work as nursing assistant.

Conclusion: The presence of dystonic features alter DBS target selection in DT. Though Vim is usually the first target attempted when postural-action tremor is the main complaint. Occasionally, a second rescue DBS lead may be necessary. The promise of a single target to reliably improve both tremor and dystonia in an individual case remains unclear. The use of directional leads could help to sort out this dilemma.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/directional-stimulation-for-dystonic-tremor/