Abstract

Background: Whereas focal and diffuse brain damage on conventional magnetic resonance imaging (cMRI) is seen in patients with neuropsychiatric systemic lupus erythematosus (NSLE), the spinal cord seems to be rarely involved. Diffusion tensor (DT) MRI provides information on the patterns of tissue disruption of the central nervous system, which may go undetected by cMRI.

Objective: To quantify the extent of otherwise “occult” injury of the cervical cord in NSLE, and to improve our understanding of its nature.

Subjects and methods: Conventional and DT MRI scans of the cervical cord and brain were acquired from 11 NSLE patients and 10 healthy controls. Histograms of mean diffusivity (MD) and fractional anisotropy (FA) of the cervical cord and brain were analyzed. Measures of cervical cord and brain atrophy and focal lesion loads were computed.

Results: Only one patient had a single focal lesion of the cord, whereas all had multiple brain lesions on cMRI scans. Cord and brain volumes did not differ between patients and controls. Mean peak height of the cervical cord MD histogram (p=0.0001) and average brain FA (p=0.001) were significantly lower in patients than in controls. Average cord MD was correlated with average brain MD (r=0.69, p=0.01) and FA (r=-0.81, p=0.002).

Conclusion: DT MRI discloses mild and otherwise “occult” cord damage in NSLE, which might be secondary to Wallerian degeneration of long-tract fibers passing trough damaged areas of the brain.