Assessment of brain white matter fiber bundle atrophy in patients with Friedreich ataxia.
OBJECTIVE
To investigate in vivo severity and topographic distribution of brain white matter (WM) fiber bundle atrophy in patients with Friedreich ataxia, a condition characterized by an uneven involvement of brain WM, and to correlate such findings with the clinical status of the patients.


METHODS
The study was conducted with institutional review board approval. Written informed consent was obtained from each participant. Sixteen patients with Friedreich ataxia and 15 healthy control subjects were studied by using a 1.5-T magnetic resonance (MR) imager and 3-mm-thick diffusion-tensor images with 15 noncollinear directions. The size of WM fiber bundles was examined at a voxel level by using a recently developed method, which relies on production of anisotropy maps and nonlinear registration. Data were analyzed by using statistical parametric mapping software and an analysis of covariance model adjusted for age and sex.


RESULTS
Compared with control subjects, patients with Friedreich ataxia had WM atrophy in (a) the central portion of the medulla oblongata, (b) the dorsal upper pons, (c) the superior cerebellar peduncles, (d) the central portion of the midbrain, (e) the medial portion of the right cerebral peduncle, (f) the peridentate region, bilaterally, and (g) the optic chiasm. The severity of the neurologic deficits correlated significantly with atrophy of the peridentate WM, bilaterally, and that of the superior cerebellar peduncle decussation.


CONCLUSIONS
Findings of this study show that it is feasible to obtain in vivo atrophy estimates of specific brain WM fiber bundles in patients with Friedreich ataxia and that such estimates correlate with patients' clinical status. This approach has the potential to provide new information that is likely to improve the understanding of the pathophysiology of inherited ataxias.
Pagani
Elisabetta
E
Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, Scientific Institute and University Hospital San Raffaele, Via Olgettina 60, 20132 Milan, Italy.
Ginestroni
Andrea
A
Della Nave
Riccardo
R
Agosta
Federica
F
Salvi
Fabrizio
F
De Michele
Giuseppe
G
Piacentini
Silvia
S
Filippi
Massimo
M
Mascalchi
Mario
M
D000328:Adult; D000704:Analysis of Variance; D016880:Anisotropy; D001284:Atrophy; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005621:Friedreich Ataxia / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016014:Linear Models; D008297:Male; D009410:Nerve Degeneration / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D011446:Prospective Studies