The authors observed a high rate of suicide (6/140 patients, 4.3%) in a large cohort of patients with movement disorders treated with deep brain stimulation (DBS). Apparent risk factors included a previous history of severe depression and multiple successive DBS surgeries, whereas there was no relationship with the underlying condition, DBS target, electrical parameters, or modifications of treatment. Paradoxically, all patients experienced an excellent motor outcome following the procedure. The authors propose that patients at high risk for suicide should be excluded from DBS surgery.

Introduction:Gait and posture in PD patients are generally analyzed in laboratory. However, laboratory techniques do not allow estimating long-term ON/OFF fluctuation in PD patients. Here, we propose an ambulatory system based on kinematic sensors that detects basic body postures and analyzes gait during long-term activity of free moving PD patients.Methods:Thirteen PD patients with subthalamic nucleus deep brain stimulation were monitored up to 5 hours with stimulation ON and OFF. A group of 10 healthy subjects performing typical daily activity was considered as control. Three wireless kinematic sensors were attached on the trunk and shanks to record basic postures (sitting, standing, lying) and gait periods. Anterio-posteror trunk’s velocity (TV) during sitting-standing transitions as well as transition duration (TD) was estimated. Also for each walking episode, gait parameters such as double support (DS), stride length (SL) and speed (SP) were extracted. Outcomes were compared to the patients’ UPDRS score.Results:Gait detection had an accuracy of 97%. A moderate significant correlation (r ≈ 0.68) between UPDRS sub-score and SL, SP and DS was found. Comparing to the normal, patients had significantly longer TD (3.3±1.0 vs. 2.7±0.5 sec) and slower TV (9.2±3.4 vs. 13.8±4.1 deg/sec). There were also significant differences in motor function between ON and OFF states.Discussion and ConclusionOur system assessed motor performance during long-term monitoring in free moving PD patients and showed significant correlation to the clinical scores. Based on gait and trunk movement it provides a new way to estimated ON/OFF fluctuation during daily activity of PD patients.

INTRODUCTION: Motor performance in Park-inson’s Disease (PD) patients is generally analyzed in laboratory. However, laboratory techniques do not allow estimating long-term ON/OFF fluctua-tion in PD patients. Here, we propose an ambula-tory system based on kinematic sensors that can detect basic body postures during daily activities of the PD patients.METHODS: 10 PD patients with sub-thalamic nucleus deep brain stimulation (STN-DBS) and 10 healthy control subjects participated in a 45 min-utes protocol of typical daily activities. PD patients did the test twice: once with stimulation ON and once with the stimulation OFF. Three kinematic sensors were attached on the trunk and shanks (see Fig.1) to detect basic postures (sitting, standing, lying) and gait periods. Using the shank sensors periods of gait were detected and using the trunk sensor lying periods and also transitions between sitting and standing were detected. Anterio-posteror trunk’s velocity (TV) during sitting-standing transitions as well as transition duration (TD) was estimated. Outcomes were compared to the patients’ UPDRS score.RESULTS: Periods and type of the body postures could be detected with a good accuracy (see Table 1). In PD patients, STN-DBS significantly (p < 0.005) reduced TD (3.27±0.42 vs. 3.54±0.53 sec) and significantly (p < 0.001) increased TV (9.65±2.29 vs. 7.85±2.20 deg/sec). However, both parameters remained significantly (p < 0.05) dif-ferent from the values of the control group (TD = 2.82±0.22 sec, TV = 13.12±2.02 deg/sec). Signifi-cant (p < 0.05) correlation between the UPDRS posture subscore (UPDRS III subscores 27, 28, 30) and TV and TD was found (r = -0.69 and r = 0.69 respectively).DISCUSSION & CONCLUSIONS: An ambula-tory method suitable to monitor daily activities of PD patients has been proposed. System could clas-sify different body postures with a high accuracy. We found that although STN- DBS significantly improved motor performance of the PD patients, their performance remained significantly different from control subjects.ACKNOWLEDGEMENTS: This work was sup-ported in part by Swiss National Science Founda- tion under grant FNRS 3152-062006.00/1.

An ambulatory gait analysis method using body-attached gyroscopes to estimate spatio-temporal parameters of gait has been proposed and validated against a reference system for normal and pathologic gait. Later, ten Parkinson's disease (PD) patients with subthalamic nucleus deep brain stimulation (STN-DBS) implantation participated in gait measurements using our device. They walked one to three times on a 20-m walkway. Patients did the test twice: once STN-DBS was ON and once 180 min after turning it OFF. A group of ten age-matched normal subjects were also measured as controls. For each gait cycle, spatio-temporal parameters such as stride length (SL), stride velocity (SV), stance (ST), double support (DS), and gait cycle time (GC) were calculated. We found that PD patients had significantly different gait parameters comparing to controls. They had 52% less SV, 60% less SL, and 40% longer GC. Also they had significantly longer ST and DS (11% and 59% more, respectively) than controls. STN-DBS significantly improved gait parameters. During the stim ON period, PD patients had 31% faster SV, 26% longer SL, 6% shorter ST, and 26% shorter DS. GC, however, was not significantly different. Some of the gait parameters had high correlation with Unified Parkinson's Disease Rating Scale (UPDRS) subscores including SL with a significant correlation (r = -0.90) with UPDRS gait subscore. We concluded that our method provides a simple yet effective way of ambulatory gait analysis in PD patients with results confirming those obtained from much more complex and expensive methods used in gait labs.