This study was performed to achieve a better definition of the nature of the disability in multiple sclerosis (MS). Axial spinal cord magnetic resonance imaging (MRI) at C5 was obtained in 15 patients with benign MS, 17 patients with secondary progressive MS and 10 healthy controls. Patients with secondary progressive MS had smaller spinal cord cross-sectional area (P = 0.01) and transverse diameter (P = 0.006) than patients with benign MS. The degree of disability was inversely correlated with both the cross-sectional area (r = -0.6, P = 0.0018) and transverse diameter (r = -0.5, P = 0.0032) of the cord. Spinal cord atrophy was found in 7 (41%) patients with secondary progressive MS and in 2 (13%) with benign MS. These findings suggest that destructive pathology within MS lesions might play a relevant role in the development of disability in MS.

In this study, we investigated the relationship between multiple sclerosis lesion volumes measured from magnetic resonance imaging scans and image-slice thickness. The lesion volume was computed using a semiautomated thresholding technique from axial scans of the brain of varying slice thickness. Ten patients were studied, and in all cases the computed lesion volume increased with decreasing slice thickness (p = 0.01). Linear extrapolation from our data allowed the lesion volume at very small slice thickness to be estimated; this was found to be on average 20% greater than that obtained using a slice thickness of 5 mm. Furthermore, there were considerable differences in the percentage of change in lesion volume from patient to patient, and it would appear that there is a larger variation with slice thickness for patients with smaller lesions and higher lesion loads.

No abstract