MRI measures show significant cerebellar gray matter volume loss in multiple sclerosis and are associated with cerebellar dysfunction.

BACKGROUND: Regional atrophy measures may offer useful information about the causes of specific clinical deficits in multiple sclerosis (MS). OBJECTIVE: To determine the magnitude of cerebellar gray and white matter (GM and WM) atrophy in patients with clinically isolated syndromes (CIS) and MS, and their role in clinical manifestations of cerebellar damage. METHODS: T1-weighted volumetric magnetic resonance imaging (MRI) of 73 patients [29 CIS, 33 relapsing-remitting MS (RRMS), 11 secondary progressive MS (SPMS)] was compared with 25 controls. GM and WM regions were generated using SPM5 and cerebellar regions delineated. Linear regression was used to investigate differences in tissue-specific cerebellar volumes between groups and the association with clinical measures. RESULTS: Mean cerebellar GM volume (CGMV) was 100.1 cm(3) in controls, 96.4 cm(3) in CIS patients, 91.8 cm(3) in RRMS patients, and 88.8 cm(3) in SPMS patients. Mean cerebellar WM volumes (CWMV) were 21.3 cm(3), 20.4 cm(3), 19.9 cm(3), and 18.8 cm(3), respectively. CGMV was reduced by 4.8 cm(3) (P = 0.054) in RRMS patients, and 8.5 cm(3) (P = 0.012) in SPMS patients, relative to controls. Only patients with SPMS showed a borderline significant reduction in CWMV compared with controls (mean 2.1 cm(3), P = 0.053). CGMV was significantly smaller in patients assessed as having cerebellar dysfunction compared with patients who had normal cerebellar function. Significant associations of CGMV and CWMV with performance on the nine-hole peg test were also observed. CONCLUSION: Clinically relevant GM atrophy occurs in the cerebellum of MS patients and is more prominent than WM atrophy. As such, it may provide complementary data to other regional atrophy and intrinsic tissue measures.