University at Buffalo - The State University of New York

Published: January 31, 2008

By LOIS BAKER
Contributing Editor

Magnetic resonance imaging (MRI) of the brain is the gold standard for monitoring the progression of multiple sclerosis (MS), but it is expensive and comes with limitations, one of which is the inability to assess fully the extent of loss of neurons.

New research by UB neurologists has shown that a technique called optical coherence tomography, or OCT, a simple and inexpensive measure employed currently to assess glaucoma, also could be used as a surrogate marker of disease status in MS and to assess the effectiveness of new and current MS treatments.

Results of the study appear online in the “in press” section of the Journal of the Neurological Sciences.

“MRI has advanced our ability to measure tissue injury in MS, but the technology cannot specifically measure changes in axonal integrity,” said Bianca Weinstock-Guttman, the study’s corresponding author and associate professor of neurology in the Jacobs Neurological Institute, which is the Department of Neurology in the School of Medicine and Biomedical Sciences.

“OCT may be helpful in monitoring disease progression, but also could represent a potential sensitive tool or outcome measure for future trials using neuroprotective therapeutic interventions. It is considered a reliable and objective technique for capturing loss of retinal ganglion cell axons in early glaucoma and in other forms of optic neuropathy.” Optic neuropathy (ON) is the initial presenting sign in 20 to 25 percent of MS patients.

Weinstock-Guttman noted that the retina is unique as a model of neurodegeneration and neuroprotection because it contains no myelin.

“This organization is advantageous,” she said, “because changes in the structure of the retinal-nerve-fiber layer principally represent axonal damage, whereas the myelin wrapping around the axons into the optic nerve begins behind the eye. Consequently, the retina can be used to focus on the neuronal and axonal components of MS pathological changes.”

The study involved a retrospective review of scans of 30 patients with relapsing-remitting MS (characterized by acute attacks with full or partial recovery) who were seen at the Baird Multiple Sclerosis Center, the clinical section of the JNI. All patients had received OCT, and 18 also were analyzed by MRI. All scans were analyzed at the Buffalo Neuroimaging Analysis Center (BNAC), also part of UB’s JNI.

Results showed that the thickness of the retinal-nerve-fiber layer (RNFL) as assessed by OCT was strongly associated with MRI findings of brain atrophy and lesion volume, said Weinstock-Guttman.

“Furthermore, we found a negative correlation between average RNFL thickness (average of both eyes) and disability, as assessed by the Expanded Disability Status Scale (EDSS), the gold standard measure used in MS.

“The results demonstrate that OCT can be an excellent patient-monitoring technique because the decrease in RNFL thickness reflects inflammatory and neurodegenerative components of MS,” she said. “Further studies are needed to assess and validate OCT measures versus MRI measures and to delineate the role of OCT in patients with relapsing and progressive forms of MS.

Erica Grazioli, UB clinical instructor of neurology, was first author on the paper. Additional contributors were Robert Zivadinov, director of the BNAC and associate professor of neurology; Norah Lincoff, clinical professor of ophthalmology; Jan Rang Wong; David Hojnacki, clinical instructor of neurology; Sara Hussein; Jennifer Cox, assistant professor of neurology and director of clinical imaging at the BNAC; Murali Ramanathan, associate professor of neurology and pharmaceutical sciences; and Monica Baier from the University of Alabama.

The study was funded in part by a grant from “Jog for the Jake.”