The effects of multiple sclerosis (MS) extend beyond visibly affected areas into large portions of the brain that outwardly appear normal, according to a study appearing in the September issue of Radiology.
"This disease process in the normal-appearing brain tissue affects the brain globally and has substantial clinical impact," said the study's lead author, Hugo Vrenken, Ph.D., from the Multiple Sclerosis Center at VU University Medical Center in Amsterdam, The Netherlands.
MS is a chronic, autoimmune disease characterized by the destruction of myelin, the protective layers that surround nerve cells. It can affect numerous body functions, and symptoms may include visual and speech impairment, memory loss, depression, muscle weakness, loss of coordination, numbness or pain, bowel and bladder problems and sexual dysfunction.
MS affects approximately 400,000 people in the United States and as many as 2.5 million worldwide, mostly women between the ages of 20 and 50, according to the National Multiple Sclerosis Society.
"The areas of demyelination, or lesions, in patients with MS can be visualized with magnetic resonance imaging (MRI). However, the volume of lesions visible at MRI only correlates moderately with clinical disability measurements," Dr. Vrenken said. "This may be due to disease activity outside the visible lesions."
To gain a better understanding of the effects of MS on the whole brain, Dr. Vrenken and colleagues studied T1 changes in normal-appearing white and gray brain matter in patients with MS.
T1 is a measurement of proton relaxation after exposure to a magnetic field and a radiofrequency (RF) pulse. Due to this RF pulse, protons in the body first reach an excited state and then relax back to a state of equilibrium by funneling the excess energy to the surrounding tissues. T1 refers to the time required for protons to relax to the equilibrium state in this particular manner.