April 30, 2004
Doctors may be able to predict whether therapeutic plasma exchange is worthwhile for patients with multiple sclerosis by determining the neuropathological subtype pattern of a particular individual, according to researchers speaking here on April 28th at the American Academy of Neurology 56th Annual Meeting.
Mark Keegan, MD, Neurologist, Mayo Clinic, Rochester, Minnesota, United States, said that all 10 patients who were identified as having Pattern-II subtypes responded to treatment with therapeutic plasma exchange, while none of the 9 other patients who exhibited other patterns responded.
"This study shows that pathological subtype of multiple sclerosis is an important factor in predicting response to therapeutic plasma exchange," Dr. Keegan said.
Dr. Keegan works with co-author Claudia Lucchinetti, MD, Associate Professor of Neurology, Mayo Clinic. Dr. Lucchinetti is considered a pioneer in the investigation of how MS subtype patterns influence the course of the disease and treatment options.
Active MS lesions may be classified neuropathologically into 4 distinct subtypes, according to the work of Dr. Lucchinetti's group. Pattern I and Pattern II are characterised by prominent lymphocyte and macrophage infiltration, oligodendrocyte survival, and remyelination. Pattern II differs from Pattern I, however, in that there is the presence of complement activation and immunoglobulin deposition in Pattern II. (Pattern III and Pattern IV also involve T cells and macrophages, but they lack complement activation, display limited remyelination and are characterised by oligodendrocyte loss, suggesting a primary oligodendrogliopathy. Pattern IV is considered rare.)
The researchers sought to determine whether neuropathological pattern determination had therapeutic implications, especially in employment of therapeutic plasma exchange. Therapeutic plasma exchange appears effective in treating acute, severe attacks of central-nervous-system demyelinating diseases that are not responsive to corticosteroids.
"Clinical improvement is rapid and dramatic in some patients," Dr. Keegan said, "but therapeutic plasma exchange is ineffective in others."
In this study, Dr. Keegan and colleagues from both Mayo Clinic and Gottingen, Germany retrospectively assessed treatment outcomes in patients with a pathologically diagnosed MS subtype who underwent treatment with therapeutic plasma exchange during an acute, severe demyelinating disease exacerbation. Active demyelinating lesions were determined immunopathologically by pattern, based on Dr. Lucchinetti's published criteria. Clinical outcome was assessed separately from immunopathological classification, and graded as "no improvement," "mild," "moderate" or "marked improvement" in index attack signs and symptoms. Only moderate or marked improvement with definite functional recovery was considered a treatment success.
"Multiple-sclerosis patients with Pattern-II pathology are more likely to have a beneficial response to therapeutic plasma exchange than those with Pattern I or Pattern III," Dr. Keegan reported.
[Presentation title: "Multiple Sclerosis Pathological Subtype Predicts
Response to Therapeutic Plasma Exchange." Abstract #S29.002.]
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