Evaluation of heart rate and blood pressure variability in Parkinson's disease patients after bilateral subthalamic deep brain stimulation]

Autonomic dysfunctions are the most common non-motor symptoms of Parkinson's disease (PD) and often precede the motor symptoms of the disease. Autonomic dysfunction may be a dominant symptom of the advanced stages of PD as well as a major cause of patient disability. Despite the wide use of neurostimulation in clinical practice, the effect of deep brain stimulation of subthalamic nucleus (STN DBS) on autonomic symptoms of PD still remains only partially understood. The aim of the study is evaluation of heart rate variability (HRV) and blood pressure variability (BPV) in patients with PD before STN DBS and following bilateral STN DBS.The study included 25 subjects aged between 31 and 71 years, diagnosed with the idiopathic PD and selected for treatment with STN DBS. All the patients were in advanced stages of PD, disease duration ranged from 5 to 22 years. The patients enrolled into this study underwent STN DBS. Neurological examination including assessment of the severity of parkinsonism according to UPDRS scale, a psychological examination and an electrophysiological examination of autonomic disturbances based on heart rate and blood pressure variability were conducted on all patients two weeks before and three months after STN DBS.After STN DBS an improvement in terms of the analyzed parts of the UPDRS has been shown. The improvement of motor disorders assessed by III part UPDRS during the "off" medication/stimulation "on" was 67.8%. Orthostatic hypotension before the STN DBS procedure was observed in 56% of patients and after STN DBS in 53% of them. Before STN DBS the imbalance of the sympathetic--parasympathetic components with the predominance of the sympathetic based on HRV parameters--the ratio LF/HF-RRI (2.5) and a higher rate of LFnu (61.3%) than HFnu (38.6%) has been shown. Three months post STN DBS an increase parameters of spectral analysis of HRV in the low frequency LF-RRI, and high-frequency HF-RRI and the total power spectrum PSD-RRI was observed. After STN DBS an increase of parameters of spectral analysis of systolic BPV, very low frequency VLF-sBP, low frequency LF-sBP and total power spectrum PSD-sBP was noted.Results of the study suggest that STN DBS is an effective treatment method of both motor symptoms and autonomic dysfunctions. The disturbances of HRV and BPV before and after STN DBS indicate the increase of autonomic system activity with sympathetic dominance.