gms | German Medical Science

To investigate the long-term effect of deep brain stimulation on generalised or multifocal dystonia.

From February 1999 through December 2004, 31 pts. suffering from medically intractable dystonia have been enrolled in a prospective study. Eight cases with a minimum follow-up of 3 years have been considered for long-term analysis. Diagnoses were hereditary torsion dystonia (HTD) in 3 pts., sporadic torsion dystonia (STD) in 4 pts, and secondary dystonia (SD) in one case. Target definition based upon atlas data using ventriculography together with 3D stereotactic CT- and MR-imaging. Surgery was performed in general (5 pts) or local (3 pts.) anaesthesia. In the latter group intraoperative microelectrode recording was applied. In all patients, the final position of the quadrupolar electrode (Medtronic^® model 3389) was documented on stereotactic x-rays.

The analysed pts. (median age: 39 years) had a median actualised FU of 43.8 mths (range: 36.0-67.2). The median preoperative Burke-Fahn-Marsden-dystonia-rating-scale (BFMDRS) motor-score (part 1) was 55.5 (range: 15-106), the BFMDRS disability-score (part II) 12.0 (range: 3-29). In 4/8 pts. (3 STD, 1 SD, average FU: 56.6 months) with a time delay from the onset of dystonia (STD n=3, SD n=1) to surgery of <15 years presented with substantial and ongoing improvement of their baseline scores (BFMDRS-1: 47.2-81.5%, BFMDRS-2: 11.8-53.8%). Two pts. (HTD) with a good response at 3 months postop. worsened over time resulting finally in “minor improvement”. The remaining two cases had no improvement. Despite on case with bleeding at the site of the extension cable there were neither intra- nor postoperative complications, and nor side effects related to stimulation.

DBS in the GPi as a safe surgical method to treat dystonia has in the past been applied in an increasing number of patients. Like the experiences of others, the own data demonstrated the highly variable outcome. In half of our patients the initial good response remained stable over a long time period. The latency time from onset of dystonia symptoms to surgery may be one variable influencing the degree of improvement.