Objective: To evaluate the long-term outcome of unilateral STN DBS in highly asymmetric patients with PD.

Background: Unilateral STN DBS is suggested to be a reasonable treatment option for highly asymmetric PD because unilateral STN DBS can ameliorate the ipsilateral and axial motor symptoms and additional risk of bilateral surgery. However, long-term outcome is yet to be reported. This study is a 7-year follow up of unilateral STN DBS on highly asymmetric patients with PD.

Methods: Eight patients with highly asymmetric PD who underwent unilateral STN DBS. The electrode was implanted on the STN contralateral to the more affected side. The patients were followed up for mean 7 years after the first surgery. The assessments included motor Unified Parkinson’s disease Rating Scale (UPDRS), Hoehn-Yahr (HY) stage, and levodopa equivalent daily dose (LEDD). The evaluations were carried out at 3, 6, 12 months and yearly after first surgery. Serial changes of the ipsilateral, axial, contralateral UPDRS, and LEDD were analyzed.

Results: During follow-up after first unilateral surgery (mean 91.5 months, range 36-105), seven of 8 patients wanted second surgery since the effect of unilateral surgery combined with medical treatment had become unsatisfactory. Four of 7 patients underwent second surgery at 58.5 ± 11.6 months after the first surgery. Three patients were not able to have second surgery due to other medical and/or financial problems. The total UPDRS III score, the mean axial UPDRS score, and LEDD returned to the baseline 3 years after the first surgery. The improvement in contralateral UPDRS subscore continued through 3 years. The ipsilateral UPDRS subscore worsened gradually after the first surgery and doubled at 3 years. The direction of asymmetry of motor symptoms was reversed at 6 months.

Conclusions: At least for the first few years, the unilateral procedure was beneficial, however, the benefit from unilateral STN DBS attenuated over time. Half of the patients who underwent second surgery had additional motor improvement without significant adverse effect of the second surgery. Therefore, degree of asymmetry may not sufficiently support the decision of unilateral surgery. The decision should be individualized in the light of clinical symptoms, financial support, life-expectancy, and surgical safety.

The abstract was presented at Korean Neurological Association Symposium, November, 2015.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effect-of-unilateral-subthalamic-deep-brain-stimulation-in-highly-asymmetric-parkinsons-disease-7-year-follow-up/