Salman Michael S, Sharpe James A, Lillakas Linda, Dennis Maureen, Steinbach Martin J
Section of Pediatric Neurology, Children's Hospital, University of Manitoba, Winnipeg, Manitoba, Canada.
Can J Neurol Sci. 2008 Sep;35(4):495-500. doi: 10.1017/s0317167100009185.
Chiari type II malformation (CII) is a developmental anomaly of the cerebellum and brainstem, which are important structures for processing the vestibulo-ocular reflex (VOR). We investigated the effects of the deformity of CII on the angular VOR during active head motion.
Eye and head movements were recorded using an infrared eye tracker and magnetic head tracker in 20 participants with CII [11 males, age range 8-19 years, mean (SD) 14.4 (3.2) years]. Thirty-eight age-matched healthy children and adolescents (21 males) constituted the control group. Participants were instructed to 'look' in darkness at the position of their thumb, placed 25 cm away, while they made horizontal and vertical sinusoidal head rotations at frequencies of about 0.5 Hz and 2 Hz. Parametric and non-parametric tests were used to compare the two groups.
The VOR gains, the ratio of eye to head velocities, were abnormally low in two participants with CII and abnormally high in one participant with CII.
The majority of participants with CII had normal VOR performance in this investigation. However, the deformity of CII can impair the active angular VOR in some patients with CII. Low gain is attributed to brainstem damage and high gain to cerebellar dysfunction.
Chiari II型畸形（CII）是小脑和脑干的一种发育异常，而小脑和脑干是处理前庭眼反射（VOR）的重要结构。我们研究了CII畸形在主动头部运动期间对角向VOR的影响。
使用红外眼动追踪仪和磁头追踪仪记录了20例CII患者（11例男性，年龄范围8 - 19岁，平均（标准差）14.4（3.2）岁）的眼动和头部运动。38名年龄匹配的健康儿童和青少年（21例男性）组成对照组。参与者被要求在黑暗中“注视”25厘米外的拇指位置，同时他们以约0.5赫兹和2赫兹的频率进行水平和垂直正弦头部旋转。使用参数检验和非参数检验对两组进行比较。
两名CII患者的VOR增益（眼速与头速之比）异常低，一名CII患者的VOR增益异常高。
在本研究中，大多数CII患者的VOR表现正常。然而，CII畸形可损害一些CII患者的主动角向VOR。增益低归因于脑干损伤，增益高归因于小脑功能障碍。
