Cortical functional reorganization and its relationship with brain structural damage in patients with benign multiple sclerosis.
BACKGROUND
Patients with multiple sclerosis (MS) who have a favourable clinical status several years after disease onset are classified as 'benign'. In many cases brain tissue damage does not differ between benign MS and the 'classical' MS forms.


OBJECTIVE
To assess whether the favourable clinical course in benign MS could be explained by the presence of an efficient functional cortical reorganization.


METHODS
Twenty-five right-handed patients with benign MS (defined as having Expanded Disability Status Scale ≤ 3 and disease duration >15 years) underwent functional MRI during a simple motor task (right-hand tapping) to assess movement-associated brain activation. This was compared with that of 10 patients with relapsing-remitting MS and 10 normal controls. Benign MS patients also underwent conventional brain MRI and magnetization transfer imaging, which was compared with an identical examination obtained 1 year before. Quantitative structural magnetic resonance measures were baseline and changes over time in T2-lesion volume, magnetization transfer ratio in T2 lesions and normal-appearing brain and total brain volume.


RESULTS
Movement-related activation was greater in patients with benign MS than in those with relapsing-remitting MS or normal controls, extensively involving bilateral regions of the sensorimotor network as well as basal ganglia, insula and cerebellum. Greater activation correlated with lower T2-lesion magnetization transfer ratio, and with decreasing brain volume and increasing T2 lesion volume.


CONCLUSIONS
The results suggest that bilateral brain networks, beyond those normally engaged in motor tasks, are recruited during a simple hand movement in patients with benign MS. This increased activation is probably the expression of an extensive, compensatory and tissue-damage related functional cortical reorganization. This can explain, at least in part, the favourable clinical expression of patients with benign MS.
Giorgio
Antonio
A
Department of Neurological and Behavioural Sciences, University of Siena, Italy.
Portaccio
Emilio
E
Stromillo
Maria Laura
ML
Marino
Silvia
S
Zipoli
Valentina
V
Battaglini
Marco
M
Blandino
Anita
A
Bartolozzi
Maria Letizia
ML
Siracusa
Gianfranco
G
Amato
Maria Pia
MP
De Stefano
Nicola
N
D000328:Adult; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology*; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology / Q000503:physiopathology*; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology*; D009473:Neuronal Plasticity / Q000502:physiology*