title: Diffusion tensor-based imaging reveals occult abnormalities in adrenomyeloneuropathy.
abstract: "Pure" adrenomyeloneuropathy (AMN) is the noninflammatory myeloneuropathic variant of X-linked adrenoleukodystrophy, where the disease process appears to be restricted to spinal cord tracts and peripheral nerves. The absence of obvious brain involvement makes it distinct from the inflammatory cerebral phenotypes of X-linked adrenoleukodystrophy. However, some pure AMN patients later experience development of cerebral demyelination, but little is known about the extent of brain involvement in pure AMN patients who have normal brain magnetic resonance imaging. We used diffusion tensor imaging to investigate possible occult cerebral abnormalities in such pure AMN patients. Fractional anisotropy and trace were studied in three-dimensional reconstructions of white matter tracts commonly involved in cerebral phenotypes of X-linked adrenoleukodystrophy. Results demonstrated reduced fractional anisotropy and increased trace in bilateral corticospinal tracts and genu of corpus callosum (p < 0.05). Diffusion tensor imaging-based three-dimensional fiber tracking showed occult tract-specific cerebral microstructural abnormalities in pure AMN patients who had a normal conventional brain magnetic resonance image. Corticospinal tract abnormalities could reflect a centripetal extension of spinal cord long-tract distal axonopathy. Accompanying abnormalities in genu of corpus callosum indicate that the disease pathology in pure AMN may not be limited to spinal cord long tracts alone, although the involvement of the latter is most prominent and severe.
authors.affiliation: Department of Neurogenetics and Functional Magnetic Resonance Imaging Kirby Center, Kennedy Krieger Institute, Baltimore, MD 21205, USA.
authors.forename: Prachi
authors.initials: P
authors.lastname: Dubey
authors.forename: Ali
authors.initials: A
authors.lastname: Fatemi
authors.forename: Hao
authors.initials: H
authors.lastname: Huang
authors.forename: Lidia
authors.initials: L
authors.lastname: Nagae-Poetscher
authors.forename: Setsu
authors.initials: S
authors.lastname: Wakana
authors.forename: Peter B
authors.initials: PB
authors.lastname: Barker
authors.forename: Peter
authors.initials: P
authors.lastname: van Zijl
authors.forename: Hugo W
authors.initials: HW
authors.lastname: Moser
authors.forename: Susumu
authors.initials: S
authors.lastname: Mori
authors.forename: Gerald V
authors.initials: GV
authors.lastname: Raymond
mesh_terms: D000326:Adrenoleukodystrophy / Q000175:diagnosis* / Q000473:pathology; D000328:Adult; D016880:Anisotropy; D001931:Brain Mapping; D016022:Case-Control Studies; D003337:Corpus Callosum / Q000473:pathology*; D003430:Cross-Sectional Studies; D038524:Diffusion Magnetic Resonance Imaging; D004185:Disability Evaluation; D007839:Functional Laterality; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D009460:Neurologic Examination; D011712:Pyramidal Tracts / Q000473:pathology*