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At least 793 records · Page 44Linked to original sources
PubMed1997

A case of Marchiafava-Bignami disease with complete recovery: sequential imaging documenting improvement of callosal lesions.

Serial CT and MR imaging findings in a 44-year-old woman with Marchiafava-Bignami disease (MBD) are reported. In the acute stage, CT studies disclosed subtle hypodensity in the splenium, and T2-weighted MR images revealed apparent high signal intensity of the splenium and the central portion of the corpus callosum. Treatment with vitamin B complex resulted in complete recovery. T2-weighted MR images obtained three weeks after admission revealed dramatic resolution of imaging abnormalities, with only faint high signal intensity remaining in the splenium. The sequential changes observed on CT and MR images provided early diagnosis of MBD and the resolution of the lesion considered as brain edema, which suggested that edema might, in addition to demyelination or necrosis, be involved in the acute progression of MBD.

Adult↗
PubMed1991

The distribution of corticocortical, thalamocortical, and callosal inputs on identified motor cortex output neurons: mechanisms for their selective recruitment.

Motor cortex neurons were identified antidromically in anesthetized cats by their axonal projections to one of six targets: (1) somatosensory cortex, (2) opposite motor cortex, (3) red nucleus, (4) lateral reticular nucleus, (5) spinal cord, and (6) ventrolateral thalamus. Three inputs to motor cortex were tested for their influences on the identified cortical efferent neurons. The tested inputs originated from ipsilateral somatosensory cortex, opposite motor cortex, and ventral thalamus. Subthreshold effects of input pathways were detected by monitoring latency variations of antidromic responses. The three afferent sources, when activated by electrical stimulation, were not equally effective on motor cortex neurons. Ipsilateral corticocortical and thalamocortical excitation were found for the majority of neurons; the influenced proportions ranged from 55% to 100%, according to the target of the output neurons. Effects from the opposite hemisphere were found for only 5% to 30% of the neurons in the same projection classes. Many neurons (36 of 81, or 44%) were excited from more than one source, but few (5 of 37, or 14%) were influenced by all three possible sources of input, even in small regions of cortex innervated by all three of the inputs. Among 19 electrode tracks where all three inputs were present, there were only 2 tracks where all the neurons shared the same combination of inputs. Even for neurons in closest anatomical proximity ("clusters"), it was unusual (only 7 of 25 clusters) for all the neurons to have the same input pattern. Among the seven clusters where all the neurons shared the same input pattern, five of the clusters projected to the same target. These variable combinations of inputs to motor cortex neurons support the conclusion that efferent neurons could be recruited selectively from separate cortical layers or from within clusters of nearby neurons, according to the target of their axonal projection.

Afferent Pathways↗
PubMed1992

Interhemispheric approach with callosal resection for distal anterior cerebral artery aneurysms. Technical note.

Distal anterior cerebral artery aneurysms are commonly found near the genu of the corpus callosum. While these aneurysms may be surgically obliterated through a variety of approaches, exposure via the interhemispheric fissure is used by many surgeons. Early identification of the afferent artery may be difficult with this approach, however, particularly if the aneurysm lies just beneath the genu of the corpus callosum. The authors have modified the interhemispheric approach to distal anterior cerebral artery aneurysms by electively exposing the feeding artery through a small anterior callosotomy. While this maneuver is not necessary for all distal anterior cerebral artery aneurysms, it can greatly enhance exposure in the region just below the genu of the corpus callosum. Experience with this technique in five patients is reported. In all cases, the limited anterior callosotomy enhanced surgical exposure. No morbidity could be attributed to the callosotomy in any patient. It is concluded that, when the interhemispheric approach is used, anterior callosotomy improves exposure of the region just below the genu of the corpus callosum and may be a useful maneuver when treating distal anterior cerebral artery aneurysms.

Corpus Callosum↗
PubMed2000

[Left unilateral melokinetic apraxia and left dynamic apraxia following partial callosal infarction].

A 69 year-old right-handed man suffered from an infarct in the left anterior cerebral territory's artery, involving the anterior and middle parts of the corpus callosum, and the cingulum. He had a right crural hemiparesis with a grasp reflex of the right hand, and ipsilaterally a melokinetic and a dynamic apraxia. Agility of the left fingers was lost: fast and nimble movements of theses fingers, and repetitive gestures of the left hand were defective. Execution of motor sequences with the left hand was disrupted by a lack of litheness in gesture series. By analogy with unilateral left ideomotor apraxia, we suggest melokinetic and dynamic apraxia could be symptomatic of an interhemispheric disconnection. Premotor cortex could have a dominance for both digital movements and programmation of gestual sequences. As a general rule, the left cortex could be preferentially activated by the nature of some tasks, particularly the execution of complex gestual series, which implie an internal speech. In theses conditions, an interhemispheric disconnection could lead some difficulties to make theses gestures with the left hand.

Aged↗