Purpose
Recently, deep brain stimulation(DBS) of subthalamic nucleus(STN)has been highlighted as treatment of Parkinson's disease(PD). DBS produces a functional lesion in the brain and reduces activity of a focal area as well as ablative procedure. In PD, increased excitatory activity of the STN abnormally activates the internal portion of the globus pallidus(Gpi), which inhibit activity of several thalamic nuclei. The reduced thalamic activity is associated with the hypokinetic symptom of PD. Therefore, reducing the overactivity of STN by stimulation might have a considerable clinical effect in PD. In this study, we investigated the effect of STN DBS on thalamic blood flow in patients with PD.
Methods
Six patients with intractable PD who underwent bilateral STN DBS were examined. Regional blood flow(rCBF) at rest was measured with perfusion SPECT in both states of stimulation-on and stimulation-off. The motor unified Parkinson's disease rating scale and Hohen and Yahr disability scale were used to evaluate the clinical condition in each state. Three-dimensional stereotactic surface projections(3D-SSP) was used to evaluate changes in thalamic blood flow by STN stimulation. The statistical difference was determined by two-sided paired t test(Stat 1tZ software). Difference with Z-score≥1.64 was considered significant.
Result
All patients showed significant improvement in motor function by STN stimulation. Bilateral STN stimulation significantly increased thalamic rCBF bilaretally in 2 patients and unilaterally in 3 patients.
Conclusion
Increase of thalamic rCBF by STN DBS seems to be caused by disinhibition of thalamus, which may contribute to significant improvement of clinical symptoms in PD.