めまいと前庭脊髄路系異常‐タクタイル・センサーによる歩行分析‐（末梢前庭障害を中心に）

Abstract

Integration of the normal equilibrium function, space orientation and cognitive functions is needed to complete straight-line walking. Also, visual and vestibular inputs play important roles in a constantly varying 3-dimensional environment to ensure smooth locomotion. However, in vestibular disorders, patients suffer problems of gait instability. The characteristics of the instability might reflect the site and severity of the lesion. How can these abnormalities be delineated objectively? To gain an understanding from the physiological viewpoint, gait analysis under eyes-opened and blindfolded conditions was conducted using tactile sensors (F-scan system) in patients with various types of vestibular lesions. All of the data were reviewed and summarized to evaluate the usefulness and limitations of this analysis method.The coefficients of variation of gait phase-related parameters were evaluated, such as stance, swing and double support, integrated foot pressure, stability, movement and average length of the trajectories of the center of force (TCOF), and the pattern of foot pressure progression during stance which can be divided into three phases: body weight acceptance, body weight translation, and body weight thrust. Comparison of the mean values was conducted using the two-tailed t-test, with p<0.05 set as the criterion for statistical significance.The patients enrolled were those with vestibular neuritis (VN; 14 cases), acoustic tumors (AT; 61 cases: 27cases of small AT and 34 cases of large AT), and spinocerebellar degeneration (SCD; 12 cases). Healthy adults (23 subjects) served as controls.Gait instability is depicted by increment of the coefficient of variation of each gait phase. Visual cue plays an important role in providing feed-forward information for steady locomotion. Unilateral vestibular lesions could shift the body center of gravity towards the lesion side, which leads to greater foot pressure on the lesion-side foot with greater horizontal sway of the TCOF during gait, especially during gait with eyes closed. An irregular pattern of foot pressure progression could also reflect gait instability, and was most prominently found in the patients with SCD. As for the average length of TCOF, significantly longer trajectories were found in SCD patients, especially as compared with the findings in vestibular neuritis.In conclusion, gait analysis with the use of a foot pressure sensor can provide useful information for understanding gait abnormalities caused by vestibular disorders. It would be clinically useful to perform gait testing for the evaluation of gait abnormalities in vertigo patients.