Granberg T, Martola J, Bergendal G, Shams S, Damangir S, Aspelin P, Fredrikson S, Kristoffersen-Wiberg M.Corpus callosum atrophy is strongly associated with cognitive impairment in multiple sclerosis: Results of a 17-year longitudinal study. Mult Scler. 2014 . pii: 1352458514560928. [Epub ahead of print]
BACKGROUND: Cognitive impairment is common in multiple sclerosis (MS) and may be subtle. The corpus callosum (the nervous bridge between the left and right sides of the brain) is essential for connectivity-demanding cognitive tasks and is significantly affected in MS, therefore it may serve as a marker for cognitive function.
OBJECTIVE:The objective of this paper is to longitudinally study the normalized corpus callosum area (nCCA) as a marker of cognitive function and disability in MS.
METHODS:Thirty-seven MS patients were followed from 1996 with follow-ups in 2004 and 2013. A healthy matched control group was recruited. The Expanded Disability Status Scale (EDSS) and Symbol Digit Modalities Test (SDMT) were assessed.
RESULTS:Disease duration spanned five decades (1.6-46 years). Annual corpus callosal atrophy rate decreased with disease duration. nCCA was strongly correlated with SDMT (r = 0.793, p < 0.001) and moderately correlated with EDSS (r = -0.545, p < 0.001) after adjusting for disease duration, age and sex.
CONCLUSIONS:The nCCA correlates well with physical and cognitive disability in time perspectives close to two decades, outperforming volumetric measurements. The nCCA is fast and could be feasible for clinical implementation where it may help identify patients in need of neuropsychological evaluation.
The SDMT involves a simple substitution task. Using a reference key, the examinee has 90 seconds to pair specific numbers with given geometric figures. Because examinees can give either written or spoken responses, the test is well suited for use with individuals who have motor disabilities or speech disorders. Because it involves only geometric figures and numbers, the SDMT is relatively culture free as well and can be administered to individuals who do not speak English.
The corpus callosum is the nerve superhighway between the left and the right sides of the brain. This structure was monitored over seventeen years. If this structure is atrophied there was correlation between loss of activity in a brain eye motor co-ordination test.