Subthalamic deep brain stimulation effects on odor identification in Parkinson's disease

Background and purpose: Olfactory dysfunction is common in Parkinson's disease (PD) and it is one of the earliest non-motor symptoms. A few studies have suggested that deep brain stimulation of the subthalamic nucleus (STN-DBS) could improve olfactory function. Our aim was to evaluate the acute effect of bilateral STN-DBS on a commonly used smell test in PD patients. Methods: Fifteen PD patients who underwent bilateral STN-DBS and 15 controls were recruited. Patients and controls were tested for odor identification. Results: No statistical differences were documented between ON and OFF STN-DBS acute stimulation concerning olfaction. Controls presented a better performance for olfactory identification than patients. Conclusions: Our exploratory study did not support that bilateral STN-DBS could have an acute effect on olfactory function in PD patients.