NEW YORK (Reuters Health) – Chronic bilateral deep brain stimulation of the globus pallidus internus produces both symptomatic and functional improvements in patients with complex cervical dystonia, German researchers report. They have also found the technique useful as an adjunct to spinal surgery in patients with secondary cervical myelopathy.
Dr. Joachim K. Krauss, of University Hospital, Klinikum Mannheim, and colleagues prospectively evaluated five patients with cervical dystonia who had dystonic postures and phasic head movements. The patients had failed medical therapy, including botulinum toxin injections, and were not considered candidates for peripheral surgery.
After implantation of the electrodes and pulse generator, some degree of improvement was evident as soon as the patients recovered from anesthesia, the research team reports in the Journal of Neurology, Neurosurgery and Psychiatry for February. Over the next 6 months, further improvement of the phasic head movements, and then of the dystonic postures, occurred gradually as the stimulation settings were adjusted.
On the Toronto western spasmodic torticollis rating scale, scores at 3 months were significantly improved over preoperative scores, with 38% improvement on the severity subscale, 54% on the disability subscale and 38% on the pain subscale. At the latest follow-up, at 30 months, scores for severity and disability, although not pain, were significantly better than at 3 months.
The investigators also evaluated three patients with cervical myelopathy due to movement disorders: a man with generalized dystonia and two women with severe dyskinesias due to choreoathetoid infantile cerebral palsy. In these patients, electrodes were implanted 1 month after spinal surgery or 3 months before, respectively.
In the two women the severity and frequency of cervical dyskinesias improved, Dr. Krauss and his associates observed, although (consistent with previous research) "the improvement at 12 and 18 months was no better than that at 3 months and was less marked than that seen in the patients with idiopathic cervical dystonia."
In the man, who required halo immobilization after surgery, improvement of dystonic posture was almost complete by the time immobilization was discontinued, and the improvement persisted throughout 24 months of follow-up. In all three patients, progression of myelopathy stopped and there was subjective improvement of the movement disorders.
The authors conclude that pallidal deep brain stimulation is worth considering for patients "with continuous phasic movements, marked dystonic head tremor or myoclonus, severe retrocollis, sagittal and lateral translations, and antecollis with involvement of deep cervical muscles," as well as for those with less complex cervical dystonia.