Moore Steven T, MacDougall Hamish G, Ondo William G
Department of Neurology, Mount Sinai School of Medicine, Box 1135, 1 E 100th Street, New York, NY 10029, USA.
J Neurosci Methods. 2008 Jan 30;167(2):340-8. doi: 10.1016/j.jneumeth.2007.08.023. Epub 2007 Sep 2.
Freezing of gait (FOG) is common in advanced Parkinson's disease (PD), is resistant to treatment and negatively impacts quality of life. In this study an ambulatory FOG monitor was validated in 11 PD patients. The vertical linear acceleration of the left shank was acquired using an ankle-mounted sensor array that transmitted data wirelessly to a pocket PC at a rate of 100 Hz. Power analysis showed high-frequency components of leg movement during FOG in the 3-8 Hz band that were not apparent during volitional standing, and power in this 'freeze' band was higher (p=0.00003) during FOG preceded by walking (turning or obstacles) than FOG preceded by rest (gait initiation). A freeze index (FI) was defined as the power in the 'freeze' band divided by the power in the 'locomotor' band (0.5-3 Hz) and a threshold chosen such that FI values above this limit were designated as FOG. A global threshold detected 78% of FOG events and 20% of stand events were incorrectly labeled as FOG. Individual calibration of the freeze threshold improved accuracy and sensitivity of the device to 89% for detection of FOG with 10% false positives. Ambulatory monitoring may significantly improve clinical management of FOG.
冻结步态（FOG）在晚期帕金森病（PD）中很常见，对治疗有抵抗性，并且对生活质量有负面影响。在本研究中，一种动态FOG监测仪在11名PD患者中得到验证。使用安装在脚踝上的传感器阵列获取左小腿的垂直线性加速度，该传感器阵列以100Hz的速率将数据无线传输到掌上电脑。功率分析显示，在FOG期间，腿部运动在3-8Hz频段的高频成分在自主站立时并不明显，并且在行走（转弯或遇到障碍物）后出现的FOG期间，这个“冻结”频段的功率高于休息（步态起始）后出现的FOG（p = 0.00003）。冻结指数（FI）定义为“冻结”频段的功率除以“运动”频段（0.5-3Hz）的功率，并选择一个阈值，使得高于此限值的FI值被指定为FOG。一个全局阈值检测到78%的FOG事件，20%的站立事件被错误标记为FOG。对冻结阈值进行个体校准可将设备检测FOG的准确性和灵敏度提高到89%，假阳性率为10%。动态监测可能会显著改善FOG的临床管理。
