Classification of acquired lesions of the corpus callosum with MRI

MRI has facilitated diagnostic assessment of the corpus callosum. Diagnosti c classification of solitary or multiple lesions of the corpus callosum has not attracted much attention, although signal abnormalities are not uncomm on. Our aim was to identify characteristic imaging features of lesions freq uently encountered in practice. We reviewed the case histories of 59 patien ts with lesions shown on MRI. The nature of the lesions was based on clinic al features and/or long term follow-up (ischaemic 20, Virchow-Robin spaces 3, diffuse axonal injury 7, multiple sclerosis 11, hydrocephalus 5, acute d isseminated encephalomyelitis 5, Marchiafava-Bignami disease 4, lymphoma 2, glioblastoma hamartoma each 1). The location in the sagittal plane, the re lationship to the borders of the corpus callosum and midline and the size w ere documented. The 20 ischaemic lesions were asymmetrical but adjacent to the midline; the latter was involved in new or large lesions. Diffuse axona l injury commonly resulted in large lesions, which tended to be asymmetrica l; the midline and borders of the corpus callosum were always involved. Les ions in MS were small, at the lower border of the corpus callosum next to t he septum pellucidum, and crossed the midline asymmetrically. Acute dissemi nated encephalomyelitis and the other perivenous inflammatory diseases caus ed relatively large, asymmetrical lesions. Hydrocephalus resulted in lesion s of the upper part of the corpus callosum, and mostly in its posterior two thirds; they were found in the midline. Lesions in Marchiafava-Bignami dis ease were large, often symmetrically in the midline in the splenium and did not reach the edge of the corpus callosum.