Anti-cholinergics for axial symptoms in Parkinson's disease after subthalamic stimulation.

We studied the effect of anti-cholinergic therapy on axial symptoms that show a tendency to worsen over time after deep brain stimulation of the subthalamic nucleus (STN-DBS) in patients with Parkinson's disease (PD). We conducted a prospective study of 20 consecutive patients treated with the anti-cholinergic agent trihexyphenidyl after bilateral STN-DBS and assessed the effect of anti-cholinergic therapy on parkinsonism 1 month after its initiation using the Unified Parkinson's Disease Rating Scale (UPDRS). After a mean post-operative follow-up period of 22.3 months, the scores of axial symptoms on UPDRS part II (ADL score) and part III (motor score) deteriorated by 87% and 54% (baseline), respectively, compared with the pre-operative scores (P < 0.001 for both comparisons). After adding trihexyphenidyl to dopaminergic medication with stimulation, the scores of axial symptoms on UPDRS part II and part III improved from baseline by 33% and 39%, respectively (P < 0.001 for both comparisons). Our findings demonstrated that the anti-cholinergic agent trihexyphenidyl shows positive effect for a patient population developing deterioration of axial symptoms after STN-DBS. The results in the present study may provide insights into the mechanism of emergence or progression of axial symptoms in patients with PD after STN-DBS.