Dec. 7, 2011 (HealthDay News) — Multiple sclerosis may begin in the outer layer of the brain and work its way into the deep interior, according to a new study that upends long-held beliefs about the nervous system disease.
The new findings, which could spur changes in the way MS is diagnosed and treated, appear to solidify a theory that's emerged in recent years. This new premise suggests that gray matter, the outer covering of the brain called the cortex, and the fluid that surrounds and cushions it, is where MS originates, not in the bulky white matter that composes most of the brain's core.
It's an "outside-in" process in other words, said study co-author Dr. Claudia Lucchinetti, a professor of neurology at the Mayo Clinic in Rochester, Minn.
"We already recognized before this study that the cortex — the superficial layer where cells control memory, attention, and other key pathways in the nervous system — was involved in MS. But most of what we knew came from autopsy studies, from patients who had longstanding disease, 30 to 50 years," said Lucchinetti. The new findings show the cortex is involved early on and may even be the initial target of the disease, she added.
Lucchinetti and her colleagues analyzed brain tissue of early MS patients obtained through biopsies. The tissue was primarily white matter, but about one-fourth of the biopsies (138 of 563 patient screenings) also included tiny fragments of cortex. The scientists used that tissue as the focus of their study.
The cortical tissues were viewed on a microscopic level. "The early lesions were highly inflammatory," said Lucchinetti, whose research is published in the Dec. 8 issue of the New England Journal of Medicine.
The authors also noted that inflammation was also present in the meninges, the protective membranes that cover the surface of the brain and spinal cord, and was strongly associated with inflammation in the cortex tissue.