Department of Neurology, Mount Sinai School of Medicine, Human Aerospace Laboratory, 10029, New York, NY, USA.
J Neuroeng Rehabil. 2013 Feb 13;10:19. doi: 10.1186/1743-0003-10-19.
We have previously published a technique for objective assessment of freezing of gait (FOG) in Parkinson's disease (PD) from a single shank-mounted accelerometer. Here we extend this approach to evaluate the optimal configuration of sensor placement and signal processing parameters using seven sensors attached to the lumbar back, thighs, shanks and feet.
Multi-segmental acceleration data was obtained from 25 PD patients performing 134 timed up and go tasks, and clinical assessment of FOG was performed by two experienced raters from video. Four metrics were used to compare objective and clinical measures; the intraclass correlation coefficient (ICC) for number of FOG episodes and the percent time frozen per trial; and the sensitivity and specificity of FOG detection.
The seven-sensor configuration was the most robust, scoring highly on all measures of performance (ICC number of FOG 0.75; ICC percent time frozen 0.80; sensitivity 84.3%; specificity 78.4%). A simpler single-shank sensor approach provided similar ICC values and exhibited a high sensitivity to FOG events, but specificity was lower at 66.7%. Recordings from the lumbar sensor offered only moderate agreement with the clinical raters in terms of absolute number and duration of FOG events (likely due to musculoskeletal attenuation of lower-limb 'trembling' during FOG), but demonstrated a high sensitivity (86.2%) and specificity (82.4%) when considered as a binary test for the presence/absence of FOG within a single trial.
The seven-sensor approach was the most accurate method for quantifying FOG, and is best suited to demanding research applications. A single shank sensor provided measures comparable to the seven-sensor approach but is relatively straightforward in execution, facilitating clinical use. A single lumbar sensor may provide a simple means of objective FOG detection given the ubiquitous nature of accelerometers in mobile telephones and other belt-worn devices.
我们之前发表了一种使用单支腿装加速计客观评估帕金森病(PD)冻结步态(FOG)的技术。在此,我们通过将七个传感器附在腰部、大腿、小腿和脚上,扩展了该方法,以评估传感器放置和信号处理参数的最佳配置。
从 25 名 PD 患者进行的 134 次计时起坐任务中获得多节段加速度数据,并由两位经验丰富的视频评估员对 FOG 进行临床评估。使用四个指标比较客观和临床测量值;FOG 发作次数的组内相关系数(ICC)和每次试验冻结的百分比时间;以及 FOG 检测的敏感性和特异性。
七传感器配置是最稳健的,在所有性能指标上得分都很高(FOG 发作次数的 ICC 为 0.75;冻结百分比时间的 ICC 为 0.80;敏感性为 84.3%;特异性为 78.4%)。更简单的单支腿传感器方法提供了类似的 ICC 值,对 FOG 事件具有高敏感性,但特异性较低,为 66.7%。从腰部传感器获得的记录在 FOG 事件的绝对数量和持续时间方面与临床评估员的记录仅具有中等一致性(可能是由于 FOG 期间下肢“颤抖”的肌肉骨骼衰减所致),但在单次试验中作为 FOG 存在/不存在的二进制测试时,具有很高的敏感性(86.2%)和特异性(82.4%)。
七传感器方法是量化 FOG 最准确的方法,最适合苛刻的研究应用。单支腿传感器提供的测量值与七传感器方法相当,但执行相对简单,便于临床使用。鉴于加速度计在移动电话和其他腰带式设备中的普遍存在,单个腰部传感器可能提供一种简单的客观 FOG 检测方法。