Evolution of Corpus Callosum Index in Patients with Relapsing Remiting Multiple Sclerosis Treated with Natalizumab (P6.116)

OBJECTIVE: Our main objective was analyze the evolution of cerebral atrophy in Multiple Sclerosis (MS) patients on treatment with Natalizumab. BACKGROUND: Axonal damage has been shown in MS patients, even in early phase, conditioning cerebral atrophy and disability. An accesible form of quantify cerebral atrophy is the Corpus Callosum Index (CCI), which has been shown a low interobserver variability and a good correlation with other atrophy indices. In patients with MS, an anual average decline in CCI of 0,01+0,02 has been demonstrated. DESIGN/METHODS: All patients on treatment with Natalizumab during one year or more were included in the study. The CCI was calculed in a basal MRI (made before treatment starting) and was compared with the CCI obtained in the last annual control MRI. RESULTS:22 patients were included in the study (54% women) with a middle age of 41+10 years. The median EDSS was 3,5 + 1,5. The average time between MRI was 36,9+11,15 months. The mean CCI was 0,374+0,037 on basal MRI and 0,364+0,036 in last control MRI. The annual CCI decrease was 0,006+0,01 and there were no changes in 59% (n=13). CONCLUSIONS:More than a half of our patients with MS on treatment with Natalizumab have not been experienced changes in CCI over an average of three years. These data could reflect a possible neuroprotective effect of Natalizumab.