Infratentorial hypointense lesion volume on T1-weighted magnetic resonanceimaging correlates with disability in patients with chronic cerebellar ataxia due to multiple sclerosis

In multiple sclerosis (MS), hypointense lesions on T1-weighted magnetic res onance imaging are thought to represent areas of tissue disruption and axon al loss. In previous studies of MS patients, infratentorial T1 hypointense lesions were found to be rare. In MS patients selected to have chronic cere bellar ataxia, we have determined the extent of infratentorial T1 hypointen se lesions and their relationship with disability. We recruited nine patien ts with chronic cerebellar ataxia due to MS. An expanded disability status scale (EDSS) assessment was performed on each. The patients' brains were th en imaged with axial-oblique dual-echo fast spin-echo and contrast-enhanced T1-weighted conventional spin-echo sequences. The number and total volume of infratentorial high-signal lesions on T2-weighted images and infratentor ial hypointense lesions on T1-weighted images were calculated by a blinded observer using a computer-assisted contouring technique. A total of 96 infr atentorial high-signal lesions were present, of which 62 (64.6%) appeared i sointense and 34 (35.4%) hypointense with respect to the surrounding brain substance on the T1-weighted images. There was a median of 3 (range 0-10) a nd median volume of 0.43 ml (range 0-0.85 ml) infratentorial TI hypointense lesions per patient. The EDSS score correlated with both the number (r = 0 .68, p = 0.043) and the volume per patient (r = 0.89, p = 0.001) of infrate ntorial T1 hypointense but not T2 high-signal lesions. Infratentorial TI hy pointense lesions are often seen in patients with MS and chronic cerebellar ataxia. They may play a significant role in the disability suffered by the se patients. (C) 2001 Elsevier Science B.V. All rights reserved.