Cortical lesions and atrophy associated with cognitive impairment in RRMS

Calabrese M, Agosta F, Rinaldi F, et al. (last author Filippi).  Arch Neurol 2009; 66:1144-1150.

Authors studied 70 patients with multiple sclerosis and 22 normal controls .  They used the Rao BRB and used a cutoff of 2 SD's below mean on at least one test of, version A of BRB to define cognitive impairment.  They also looked at T2 lesion volume, contrast enahncing lesion number, cortical lesions using double inversion recovery sequences, volume, and normalized grey matter volume.  Finding was that T2 lesion number and enahncing lesions were not important, but that cortical lesions, cortical and brain volume and gray matter involvement predicted cognitive impairment. 

Tests used in BRB were"  SRT and delayed recall, spatial and delayed recall (10/36 cutoff), PASAT 3 and SDMT, and word list generation.  See Camp et al, Brain, 1999 for normative values. (see article anyway). 

24 patients were listed as cognitively impaired.  The rate of impairment was, for SRT delayed, 12.9%; PASAT and word generation 10 %, SDMT 8.6 %, EDSS also predicted. 

Authors discussed the "cognitive impairment index" as discussed in Brain article above.  This is a continuous variable obtained by a grading system applied to each patient's score on each test, depending on number of SD's below mean normal.  Grade 0 means index was above mean for normal controls.  Grade 1 was given for mean to 1 SD below normal.  Grade 2 was 1-2 SD's  below normal.  Grade 3 was given for more than 3 standard deviations below.  The results for all tests were added to give an overlal measure of cognitive dysfunction.

Authors discussed that the CL (cortical lesion) number and volume correlated with CI index score, and deficits in attention, concentration, speed of processing, and memory.