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24-02-2014 | Parkinson's disease | Article

Deep-brain stimulation beneficial for gait freezing in Parkinson’s patients


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medwireNews: Subthalamic nucleus deep brain stimulation (STN-DBS) has a positive effect on freezing of gait (FOG) in patients with Parkinson’s disease (PD), shows research.

The rate of FOG nearly halved over the 12 months after surgery, report Sarah Vercruysse (KU Leuven, Belgium) and co-workers. And the overall severity of freezing declined in patients who continued to experience FOG.

The study included 41 patients eligible for STN-DBS, of whom 24 opted to undergo the procedure while the other 17 remained on best medical therapy. The two groups had similar demographical and clinical characteristics at baseline, except that the STN-DBS group had a significantly higher levodopa-equivalent dose (LED), at a median of 1112.5 mg/day compared with 680.0 mg/day in the group that continued with medical therapy.

“It is noteworthy that this suggests a slightly more severe disease profile in the STN-DBS group, adding strength to the positive treatment outcomes found in this group,” the team writes in the Journal of Neurology, Neurosurgery & Psychiatry.

The STN-DBS group contained 20 patients with FOG, which reduced to 14 after 6 months of DBS and nine after 12 months. However, two patients without FOG at baseline developed the condition by the 12-month follow-up.

The severity of freezing in the 11 patients who had FOG after 12 months was an average of 11.45 points on the New Freezing of Gait Questionnaire, which was a significant reduction from the baseline score of 17.15 points.

All 15 patients with FOG in the medical therapy group continued to experience it, and another patient developed freezing by 6 months of follow-up, with just one remaining free of the condition at 12 months.

Two variables were significantly associated with conversion from having to not having FOG: the reduction in LED and improvement in motor fluctuations during follow-up. These variables were independent of each other, with improvement in motor fluctuations explaining 21% of the variance between converters and nonconverters and reduction in LED explaining a further 20%.

In line with recent findings, this suggests that LED is directly associated with FOG, rather than just reflecting disease severity, say the researchers, although reduction of levodopa dose has also been linked to the re-emergence of postural and gait problems in patients undergoing STN-DBS.

“These findings support the complex relationship between FOG and levodopa, suggesting that FOG is partially levodopa responsive and partially dependent on other neurotransmitter systems with extremes at both ends of the spectrum,” conclude Vercruysse et al.

medwireNews ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2014

By Eleanor McDermid, Senior medwireNews Reporter

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