1992
Year 12
Prof. W. Ian McDonald
Professor of Neurology
Institute of Neurology, London, United Kingdomom
THEME: CURRENT RESEARCH IN MULTIPLE SCLEROSI
Magnetic Resonance imaging (MRI) is a scanning modality which is exquisitely sensitive to the brain pathology in MS. In
the unenhanced scan, the MS plaque is represented as an area of high signal. Enhancement is achieved by the use of
Gadolinium-DTPA, which enters the brain only where there is an abnormality of the blood-brain barrier (BBB). This
increased permeability of the BBB occurs in MS through the vesicles in the cytoplasm of the endothelial cells. MRI
enhancement signifies the presence of inflammation. Our team has documented the sequence of events in the early MS
lesion. Serial MRI studies at less than 14-day intervals were undertaken in a large number of patients. Twelve among
them showed a typical initial increase in permeability of the BBB, and the appearance and increase in size of the
non-enhancing lesion. The subsequent gadolinium injection indicated the degree of permeability of this barrier. Over a
period, a slow diminution in size of the lesion was observed, leaving behind a small, residual lesion.
The 'disappearing element' of the acute MS lesion appears to be due to the resolving vasogenic oedema. Demyelination occurs early in the inflammatory phase of the acute lesion and is preceded by vascular changes. Remyelination appears to be more extensive early in the course of MS, and more in the case of optic neuritis in the younger patient.
The 'disappearing element' of the acute MS lesion appears to be due to the resolving vasogenic oedema. Demyelination occurs early in the inflammatory phase of the acute lesion and is preceded by vascular changes. Remyelination appears to be more extensive early in the course of MS, and more in the case of optic neuritis in the younger patient.
