Article
Computerized motion analysis of head and neck mobility in patients with chronic deep brain stimulation for segmental dystonia
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Published: | April 28, 2011 |
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Outline
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Objective: The efficacy of DBS of the globus pallidus internus (GPi) in the treatment of segmental dystonia has been assessed by clinical scores. Little is known, however, about the impact of GPi DBS on the functionally relevant restriction of head and neck mobility in segmental dystonia.
Methods: Nine patients (mean age 56.3 ± 14.7 years) with segmental dystonia were evaluated preoperatively and within a median interval of 7 months (range 4–10 months) after the initiation of bilateral GPi DBS. Using a 3D ultrasound–based system (Zebris, Germany), assessment included recordings of the maximum horizontal head rotation and the maximum lateral head inclination. In addition, both the maximum movement amplitude of the head and neck and the EMG modulation indices (MI) between activation and relaxation of the sternocleidomastoid muscle and the posterior neck muscles during the respective phases of horizontal head rotation were calculated.
Results: Maximum horizontal head rotation improved from 76.7° ± 11.1° (mean ± SE) preoperatively to 101.2° ± 8.6° with DBS postoperatively (p=0.015), and maximum lateral head and neck inclination improved from 46.7° ± 7.0° preoperatively to 59.0° ± 4.8° with DBS postoperatively (p=0.038). EMG modulation during horizontal head rotation was significantly enhanced with DBS both in the sternocleidomastoid muscles (MI 30.2% ± 14.1% preoperatively to MI 66.8% ± 4.8% on DBS, p=0.001) and in the posterior neck muscles (MI 2.13% ± 9.6% preoperatively to MI 44.7% ± 3.9% on DBS, p < 0.001).
Conclusions: Chronic DBS of the GPi significantly improves head and neck mobility in patients with segmental dystonia. The most probable mechanism of this therapeutic effect is an improved modulation of cervical muscles with enhanced activation and relaxation in the respective phases of head and neck movements.