gms | German Medical Science

Objective: The globus pallidus internus (GPi) has been established as the contemporary target of choice for deep brain stimulation (DBS) in dystonia. The thalamic Vim, however, has been preferred in patients with writer's cramp. When a patient presents with both writer's cramp and other dystonic symptoms, it is unclear which target should be chosen. Multifocal DBS is a new treatment option which can address this issue.

Method: A 23-year-old woman with multifocal primary dystonia and prominent writers' cramp underwent bilateral stereotactic implantation of DBS electrodes in the GPi and the thalamic Vim. Assessment included the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor and disability subscore, 36-item short-form health score (SF-36) and standard video recording. In the frame of a prospective study protocol, clinical outcome was assessed before and at 3, 15 and 24 months after surgery.

Results: Thalamic stimulation yielded an improvement in the writer's cramp of about 80% according to the BFMDRS subscores. At the 3 month follow-up, the BFMDRS motor subscore had decreased from 3 before surgery to 0 and the disability subscore had decreased from 6 to 2. At the same time the SF-36 had improved from 31 to 78. The effect lasted for one year. At 15 months follow-up the BFM motor subscore had increased to 10 and the disability subscore had increased to 6. The SF-36 had decreased to 67. The patient presented with an increase in dystonia of the right hand and the right foot accompanied by pain. Using bilateral and monopolar Vim thalamic stimulation did not have a marked impact in the severity of dystonia. Bilateral Gpi stimulation alone improved the dystonic symptoms in the right foot slightly, but did not address the writer's cramp. Because the patient suffered right-sided dystonia in particular, a combined contralateral thalamic and pallidal stimulation was chosen. Almost immediately we saw an improvement of both the writer's cramp and the dystonic foot after the initiation of the combined unilateral bipolar stimulation. The BFM motor subscore had decreased to 6, the disability subscore had decreased to 4 and SF-36 remained unchanged with 65. The effect was sustained at the 24 month follow-up. The combination of pallidal and thalamic stimulation finally provided an improvement of 40% in the BFM motor subscore.

Conclusions: Combined thalamic and pallidal stimulation in patients with multifocal primary dystonia may be an emergent therapy option under certain circumstances.