Thalamic damage and long-term progression of disability in multiple sclerosis.
OBJECTIVE
To estimate the relative contributions of baseline thalamic atrophy and abnormalities shown at magnetization transfer (MT) magnetic resonance (MR) imaging, as well as their 12-month changes, in predicting accumulation of disability in a relatively large sample of patients with relapse-onset multiple sclerosis (MS) during an 8-year period.


METHODS
The study was conducted with approval of the institutional review board. Written informed consent was obtained from each participant. Conventional and MT MR imaging of the brain was performed at baseline and at 12-month follow-up in 13 healthy control subjects and 73 patients with relapse-onset MS; participants were monitored with clinical visits for 8 years. The following parameters were evaluated at baseline and at 12-month follow-up: volume of lesions with high signal intensity at T2-weighted imaging, volume of lesions with low signal intensity at T1-weighted imaging, mean lesion MT ratio, thalamic fraction, and thalamic MT ratio. A multivariate analysis was used to evaluate the predictors of long-term neurologic deterioration.


RESULTS
At 8-year follow-up, 44 patients showed worsening disability. During follow-up, reduction in thalamic fraction was more pronounced in patients with relapsing-remitting MS than in those with secondary progressive MS (P = .001); thalamic MT ratio decreased only in patients with secondary progressive MS (P = .007). In the multivariable model, baseline thalamic fraction (odds ratio = 0.62, P = .01) and mean percentage change in lesion MT ratio after 12 months (odds ratio = 0.90, P = .04) were independent predictors of worsening disability at 8 years. At baseline, thalamic fraction was correlated with lesion volumes at T2-weighted imaging (r = -0.75, P < .001) and T1-weighted imaging (r = -0.60, P < .001).


CONCLUSIONS
Thalamic atrophy is correlated with long-term accumulation of disability in patients with MS. White matter lesions are likely to contribute to the loss of tissue seen in the thalamus of patients with MS.
Rocca
Maria Assunta
MA
Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, Scientific Institute and University Hospital San Raffaele, via Olgettina 60, 20132 Milan, Italy.
Mesaros
Sarlota
S
Pagani
Elisabetta
E
Sormani
Maria Pia
MP
Comi
Giancarlo
G
Filippi
Massimo
M
D000328:Adult; D001284:Atrophy / Q000473:pathology; D016022:Case-Control Studies; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology* / Q000503:physiopathology*; D010641:Phenotype; D015203:Reproducibility of Results; D013788:Thalamus / Q000473:pathology*