半側空間失認—検査法および発現機序についての考察

THE MECHANISM OF UNILATERAL SPATIAL NEGLECT

　抄録　半側空間失認の検査法について検討し，本症状の発現機序について考察した。対象は右大脳半球病変78例。方法は（1）直線の二等分（2）線分抹梢（3）図形模写（4時計描写（5）地図上定位を施行し各検査項目間の関連性を検討した。その結果，（1）"直線の二等分"と"時計描写"，および，"直線のこ等分"と"地図上定位"では互いに関連性のない結果が得られた。　（2）"線分抹消"・"図形模写"・"時計描写"および"地図上定位"では，各検査結果が一致していた。（3）"直線の二等分"で異常が認められても"線分抹消"および"図形模写"においては正常となる場合が多かった。これらのことから，"線分抹消"と"図形模写"は類似の結果を示すが，"時計描写"と"地図上定位"は他の項目と異なる要因を含む項目であると考えられた。また，"直線の二等分"，"線分抹消"，"図形模写"の3項目の中では，"直線の二等分"が最も異常を反映させやすい項目であることがうかがえた。これらの検査には，探索行動障害・記憶障害・認知障害等が反映されると考えられ，半側空間失認の解析にあたっては，より多元的なとらえ方をする必要があると考えられた。

We investigated a test for unilateral spatial neglect and discussed the mechanism of this symptom.

Seventy eight patients with lesions on the right cerebral hemisphere were examined on line bisection, line cancellation, figure copying, clock drawing and location on the map.

The statistical analysis revealed (1) there were no correlations between line bisection and clock drawing or between line bisection and location ; ( 2) those with abnormal results on line bisection were apt to indicate normal results on line cancel-lation and figure copying, while in line cancella-tion, figure copying, clock drawing and location, normal results on one task meant normal results on the other. These results indicated clock draw-ing and location might include different factors from other tasks, line bisection was the most sensitive task for unilateral spatial neglect, and abnormality on line cancellation might be similar to that figure copying.

Unilateral spatial neglect may be based on several disorders, and it may be assumed to have several aspects. One of these disorders may be defective searching. Unilateral spatial neglect may be more severe when there is sensory disturbance (hemianopsia) with a searching deficit. Otherdisorders, such as cognitive disturbance, memory disturbance and so on, may also be associated with unilateral spatial neglect, and it is necessary to consider the versatilety of this symptom.