脳梁損傷による半球間連合障害（callosal disconnexion syndrome）について—その2

INTERHEMISPHERIC ASSOCIATION DISTURBANCES DUE TO LESIONS OF THE CORPUS CALLOSUM: (CALLOSAL DISCONNEXION SYNDROME)

V・半球間連合障害の病像の問題点

　1．脳梁損傷患者の反応様式について

　以上に述べたような半球聞連合障害症候群において特徴的な現象として，劣位半球側の半球間連合障害における作話的反応があげられる。たとえば，左手の触覚呼称の場合，患者は全く答えられないのではなく，間違つた呼称を行うことが多い。Geschwindら^24）の例では，左手で腕時計を持たせると"風船"と答え，指輪に触れさせると"消しゴム"と呼称したりした。Jedynakの例^{51），56）}では，1本の鉛筆の両端を両手で同時に持たせて，"右手には何を持つていますか"と問うと，"鉛筆"と正しく答えられたが，"左手には何を持つていますか"という問には"くし"と答えた。またGeschwindの患者^24）は，左手に持つた金づちで正しく物品を打つ動作をしながら"これは髪をとく時に使うものです"と述べ，Jedynakの患者^51)，56）でも，槌をふるう動作をしながら，"私はくしを使つています"と答えた。この様な偽の答を行う現象は，言語野が劣位半球から切断（di—sconnect）された為の，一種の作話であると考えられている^25）。

Recent advances in the studies of the corpus callosum and of the callosal disconnexion syndrome were reviewed.

We proposed the following classification of variousinterhemispheric association disturbances due to either surgical or non-surgical lesions of the corpus callosum.

I. Symmetrical interhemispheric disconnexion syndrome

(a) Disturbances of interhemispheric sen- sory transfer

(i) homologous sensory informations

1. tactile-tactile matching disturbance

2. position-position matching distur- bance

signe de la main étrangère (Jedynak)

desynchronization of the bilateral symmetrical movements

3. localization-localization matching disturbance

(ii) heterogenous sensory informations

(b) Disturbances of interhemispheric sen- sory-motor associations

1. visual-motor association disturbance (crossed optic ataxia)

2. loss of learning transfer

II. Interhemispheric disconnexion syndrome of the non-dominant hemisphere

(a) Verbalization disturbances of sensory informations

1. tactile naming disturbance (of ob- jects and letters)

2. visual naming distrubance (of ob- jects, colors and letters)

3. olfactory naming disturbance

4. dichotic listening

(b) Expressive disturdances of verbal in- formations

1. ideo-motor apraxia of the non- dominant hemispheric limbs

2. agraphia of the non-dominant hem- ispheric limbs

III. Interhemispheric disconnexion sydrome of the dominant hemisphere

1. constructional apraxia of the domi- nant hemispheric limbs

2. prosopognostic disturbance in the dominant hemispheric visual field

3. other disturbances of visual-spatial functions

acalculie spatiale (Jedynak)

disturbances of the part-whole relationship perception and figural unification (Nebes)

Semiological analyses of the cases with partial lesions of the corpus callosum made it possible to isolate a posterior callosal syndrome characterized by letter naming loss in the left visual field, fre-quently associated with color naming loss in the same visual field. On the other hand, syndrome of the anterior portion of the corpus callosum con-sists of ideo-motor apraxia, agraphia and tactile naming disturbance of the left hand and the dis-turbances of interhemispheric tactile-tactile and position-position matching.

Some clinical characteristics of the neurological disorders affecting the corpus callosum were dis-cussed. We have stressed the importance of the studies in callosal disconnexion syndrome in order to elucidate the problems of functional asymmetry of the two cerebral hemispheres and thire behav-ioural independence.