Deep-brain stimulation motor benefits endure
medwireNews: Deep-brain stimulation (DBS) of the subthalamic nucleus (STN) delivers long-term reductions in disability relative to medical therapy, a study shows.
The researchers compared long-term outcomes of 19 patients with Parkinson’s disease who underwent STN-DBS with 16 who were considered to be good candidates for STN-DBS but did not undergo the procedure for reasons unrelated to their neurologic condition, mainly lack of motivation.
They found that the STN-DBS group had less motor fluctuation than the group that continued on medical therapy, and were more able to undertake activities of daily living without medication.
The two groups were similar at baseline with respect to age and disease duration, clinical and neuropsychologic scores, and the presence of dyskinesia and “off” periods. All patients were reassessed after a minimum of 4 years (average 6 years) allowing a long-term comparison of STN-DBS and medical therapy despite the lack of randomization, say lead researcher Aristide Merola (University of Torino, Italy) and team.
Motor symptoms on the Unified Parkinson’s Disease Rating Scale (UPDRS)-III worsened over time in both groups, irrespective of whether patients were on or off (12-hour washout) medication.
By contrast, scores for activities of daily living (UPDRS-II) worsened in both groups when on medication, but in the off-medication condition scores worsened only in the medical therapy group, from 17.09 to 31.10 points. Scores in the STN-DBS group remained stable from baseline to follow-up, at 21.00 and 20.14, respectively. Findings were similar with the Schwab and England scale.
Also, complications of therapy (UPDRS-IV) were significantly less severe among patients receiving STN-DBS, due to significant improvements in the duration and severity of dyskinesia, compared with no change in the medical therapy group, and a slight reduction in off time, compared with a significant increase among patients receiving medical therapy.
“Taken together, these data highlight the effectiveness of STN-DBS in improving the autonomy in [activities of daily living] by lessening the severity of motor complications,” write Merola et al in the Journal of Neurology, Neurosurgery & Psychiatry.
Mood and anxiety scores did not change in either group between baseline and follow-up. Neuropsychologic scores deteriorated slightly in both groups, but cognition in general was unaffected by STN-DBS, with the exception of phonemic verbal fluency, which significantly worsened.
“Four subjects developed a disabling dysarthria after surgery, and a mild/moderate impairment of the verbal fluency affected most of the remaining patients,” report the researchers, adding that this is in line with the findings of previous studies.
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By Eleanor McDermid, Senior medwireNews Reporter