Evidence of axonal damage in cerebellar peduncles without T2-lesions in multiple sclerosis.
BACKGROUND AND AIM
Cerebellar peduncles (CP) can be probed by diffusion tensor imaging (DTI) to evaluate the integrity of cerebellar afferent and efferent networks. Damage to the CP in multiple sclerosis (MS) could lead to serious cognitive and mobility impairment. The aim of this study was to investigate the extent and the clinical impact of CP damage in MS.


METHODS
Sixty-eight MS patients were included in this study along with 27 healthy controls (HC) and underwent an MRI on a 1.5T including T1, T2, FLAIR and DTI. Using DTI, the microstructural integrity within the CP regions (superior (SCP), inferior (ICP) and middle (MCP)) was probed while controlling for focal T2-lesions presence or absence. A general linear model was performed to test for associations between clinical scores and DTI metrics for each CP.


RESULTS
Significantly decreased fractional anisotropy (FA) and increased radial diffusivity (RD) were found in the CP of all MS patients compared to those of HC, but to a lesser extent in non-lesioned CP than those with lesions. Axial diffusivity (AD) was significantly and similarly increased in both non-lesioned and lesioned CP, but only in the SCP and ICP. Expanded disability status scale (EDSS) significantly correlated with MCP's FA (p < 0.05) and RD (p < 0.05), while MS functional composite (MSFC) significantly correlated with SCP's FA (p < 0.01) and RD (p < 0.01).


CONCLUSION
The diffusion changes (FA and RD) measured in lesioned CP are probably directly related to the presence of inflammatory and/or demyelinating lesions. In contrast, the microstructural alterations reflected by AD increase in non-lesioned CP may result either from remote effects of cerebral white matter injury (diaschisis) or primary axonal degeneration, that are associated with cognitive, sensory and motor impairments of MS patients.
['Hannoun|Salem|S|', 'Kocevar|Gabriel|G|', 'Durand-Dubief|Françoise|F|', 'Stamile|Claudio|C|', 'Naji|Amal|A|', 'Cotton|Francois|F|', 'Cavallari|Michele|M|', 'Guttmann|Charles R G|CRG|', 'Sappey-Marinier|Dominique|D|']
D000328:Adult D000704:Analysis of Variance D016880:Anisotropy D001369:Axons D002531:Cerebellum D056324:Diffusion Tensor Imaging D005260:Female D006801:Humans D016014:Linear Models D008279:Magnetic Resonance Imaging D008297:Male D009103:Multiple Sclerosis D066127:White Matter
Diffusion tensor imaging (DTI) Multiple sclerosis (MS) Axial diffusivity (AD) Inferior cerebellar peduncles (ICP) Middle cerebellar peduncles (MCP) Superior cerebellar peduncles (SCP)