Brain MRI correlates of cognitive impairment in primary and secondary progressive multiple sclerosis

Brain magnetic resonance imaging (MRI) and an extensive battery of neuropsychological tests exploring frontal functions, short and long-term memory, visuo-spatial skills, attention and language were applied to 14 patients with primary progressive multiple sclerosis (PPMS) and 17 patients with secondary progressive MS (SPMS). Patients with PPMS and SPMS did not differ in degree of physical disability, but cognitive deficits were found in 9/17 (53%) patients with SPMS and in only 1/14 (7%) of those with PPMS (p = 0.01). Patients with SPMS had higher total (p = 0.004), periventricular (p = 0.008) and non-periventricular (p = 0.04) MRI lesion loads than patients with PPMS. In detail, patients with SPMS had greater involvement of frontal (p = 0.05) and occipital (p = 0.02) horns, trigones (p = 0.04), third ventricle (p = 0.03), basal ganglia (p = 0.02), parietal (p = 0.02), temporal (p = 0.004) and occipital (p = 0.03) lobes. Patients with SPMS and neuropsychological deficits had higher non-periventricular lesion loads than patients with SPMS who did not have such deficits (p = 0.005). Our results indicate that both neuropsychological and brain MRI abnormalities are more extensive in patients with SPMS. Since physical disability was similar for both groups, disability in PPMS may be predominantly due to spinal cord involvement.