Callosal Disconnection Syndrome Research Articles

Corpus callosal agenesis and disconnection syndrome: A pediatric case study

Corpus callosal agenesis and disconnection syndrome: A pediatric case study

Corpus callosal agenesis and disconnection syndrome: A pediatric case study : Warzak, W. J., Zupancic, K., & Sherrets, S. D.

Corpus callosal agenesis and disconnection syndrome: A pediatric case study : Warzak, W. J., Zupancic, K., & Sherrets, S. D.

Callosal disconnection syndrome and knowledge of the body: a case of left hand isolation from the body schema with names.

A patient is described who presented with a disturbance of body cognition confined to the left side of the body. She showed difficulties in naming the left fingers and in moving the named left fingers. She also showed great difficulty in pointing to named parts of the body with her left hand. Earlier in the course of the disease she showed a personification phenomenon of the left hand. Brain MRI showed involvement of the entire corpus callosum, probably due to occlusion of a branch of the anterior cerebral artery. It is speculated that this syndrome is caused by disconnection of the right hemisphere from the left hemispheric body schema.

Clinical and topographical range of callosal infarction: a clinical and radiological correlation study.

A prospective clinical and radiological correlation study was performed to determine the frequency, and the clinical and radiological features of callosal infarction. From 1 January 1993 to the end of December 1993 282 cases of cerebral infarction seen in the Neurology service of the University Hospital of Dijon were studied prospectively. Eight cases with callosal ischaemic lesions were identified by CT and MRI. A callosal disconnection syndrome occurred in only five of eight patients, related to a single, large infarct or several infarctions in the anterior part of the corpus callosum. Clinical features were characterised by left ideomotor apraxia, construction apraxia, and left agraphia in all five cases. Alien hand was noted in only two cases. There were gait disorders in three cases with MRI features of multiple lacunes in a large part of the corpus callosum, and also the subcortical areas of both hemispheres. It is emphasised that callosal infarctions are not rare and that they contribute to the clinical features of strokes. As well as the classic incomplete callosal disconnection syndrome, these callosal ischaemic lesions may induce non-specific gait disorders.

Hemispheric asymmetry of event-related potentials in a patient with callosal disconnection syndrome: a comparison of auditory, visual and somatosensory modalities

To investigate whether callosal lesions affect the distribution of event-related potentials (ERP) between the two hemispheres and whether hemispheric ERP distribution differs among sensory modalities, a patient with interhemispheric disconnection syndrome and 47 controls were subjected to an oddball paradigm. High (target) and low tone bursts for auditory, red (target) and green lights for visual and electrical stimuli delivered to the index (target) or fifth finger for somatosensory ERPs were presented to the unilateral ear, visual field and hand, respectively. The subjects were instructed to press a button with the hand on the stimulated side. The results showed that the hemispheric asymmetry of the patient's auditory ERPs was not significantly different from that of the controls, regardless of which ear was stimulated. In contrast, the visual and somatosensory ERPs showed a delay of the P3 latency and an attenuation of the N1-P2 and N2-P3 amplitude over the hemisphere ipsilateral to the stimulus, regardless of the stimulated side. These findings suggest that the source of P3 generation is relatively lateralized to the hemisphere contralateral to the stimulus, and that the callosal transfer of visual and somatosensory information is involved in the P3 generation in the hemisphere ipsilateral to the stimulus.

Complete callosal disconnection after closed head injury

We report a patient with complete callosal disconnection syndrome after severe closed head injury. MRI showed a complete destruction of the corpus callosum throughout its length. Although traumatic callosal lesions are a frequent finding in autopsy studies, as well as in some recent MRI studies, clinical signs of callosal disconnection are rarely observed after head injuries and a complete disconnection syndrome has not been reported yet. This case study and the review of other reported cases suggest that posttraumatic callosal disconnection is probably often overlooked. Our patient had also a severe memory disorder that might be partly related to the bilateral involvement of the fornix, as this structure is closely adjacent to the posterior corpus callosum, and was also shown by MRI to be very probably damaged.

Naturalistic action and praxis in callosal apraxia

Abstract We report a subject who, subsequent to closed head injury, demonstrated a severe left hand ideational apraxia and apraxic agraphia, consistent with callosal disconnection syndrome. In contrast to the left hand, performance of the right hand was unimpaired on traditional tests of gesture to command, sight of object, and with actual object use, but proved deficient on tests of spatial and constructional ability. We examined the consequences of these hand-specific deficits for the performance of naturalistic action tasks. The patient made errors with each hand; however, the right hand performed more poorly than the left hand. In addition, the types of errors made by each hand differed in a manner consistent with the results of neuropsychological testing and indicative of disconnection phenomena. We suggest that unlike gesture, naturalistic action requires the contribution of the specialized abilities of each hemisphere, integrated across callosal structures. Traditional testing of gesture may undere...

Subcortical coordination of hemisphere activity in commissurotomized patients.

Despite their commissurotomy, 'split-brain' patients behave as unified individuals and seldom display signs of hesitation and dissociation in their activities. Yet our current understanding of the callosal disconnection syndrome suggests that the two isolated hemispheres cannot work in parallel and that only one hemisphere at a time is responsive to bilateral stimulation. To examine this divergence, the two hemispheres of complete forebrain commissurotomy patients were simultaneously presented with colour stimuli associated with opposite responses, and the patients had to produce a single finger response whose accuracy depended on their capacity to resolve the conflicting information. Although the two patients differed in their efficiency, they were capable of accurate performance in the bilateral conflict condition, but could not correctly cross-compare the information received by each hemisphere. This performance suggests that the two disconnected hemispheres can work in parallel and process the incoming information efficiently. The outcome of these hemispheric operations may be integrated in subcortical 'centrencephalic' areas that coordinate the activities of the two sides of the brain and maintain some unity within cerebral structures.