Conflict of intentions due to callosal disconnection

Objectives-Three patients with callosal syndrome manifested a peculiar symp tom in that they were unable to perform intended whole body actions because another intention emerged in competition with the original one. Attempts w ere made to clarify the symptomatology of this manifestation and its possib le mechanism is discussed. Methods-The three patients are described and previous reports on patients w ith callosal damage were reviewed. Four additional patients with similar sy mptoms were found and the clinical features common to all seven patients we re examined. Results-This symptom could not be attributed to unilateral movement disorde rs such as unilateral apraxia, intermanual conflict, or compulsive manipula tion of tools. The manifestations included marked hesitation in initiating actions, interruption of actions, repetitive actions, and performance of un intended actions with difficulty in correcting them. All patients, except o ne, had a lesion in the posterior half of the body of the corpus callosum, and there was no significant involvement of the cerebral cortex. The sympto m became manifest later than 4 weeks after callosal damage. It occurred dur ing spontaneous actions, but not during well automated actions nor when fol lowing instructions. Conclusion-This symptom, tentatively named "conflict of intentions", can be regarded as a fragment of diagonistic dyspraxia originally described by Ak elaitis, although it can occur independently of intermanual conflict. Norma lly, the right and left cerebral hemispheres may be complementarily modifyi ng automated whole body actions in order to adapt behaviour to changes of t he environment as well as to the intention. Partial callosal disconnection without significant cortical involvement would exaggerate the disparity bet ween the role of each hemisphere through the reorganisation of neural syste ms after callosal damage. Such double, often contrary, behavioural tendenci es may sometimes simultaneously enter the patient's awareness.