American Journal of Neuroradiology
DOI 10.3174/ajnr.A1791
BRAIN
Diffuse White Matter Damage Is Absent in Neuromyelitis Optica

ákFrom the Department of Neurology (F.A.-E., W.K.), SMZ-Ost Donauspital, Vienna, Austria; and Department of Radiology (M.K., D.P.) and Institute of Neurology (R.H.), Medical University of Vienna, Vienna, Austria.
Please address correspondence to Fahmy Aboul-Enein, MD, Department of Neurology, SMZ-Ost Donauspital, Langobardenstr 122, A-1220, Vienna, Austria; e-mail: fahmy.aboul-enein{at}chello.at
BACKGROUND AND PURPOSE: Neuromyelitis optica (NMO) is an idiopathic mostly relapsing inflammatory disease with attacks on the optic nerves and spinal cord. Whether NMO is a separate disease or a subtype of classic multiple sclerosis (MS) is unclear. Clinically, CSF and MR imaging parameters and histopathologic data suggest that the normal-appearing white matter (NAWM) may be affected in MS but not in patients with NMO. Therefore, we hypothesized that the NAWM in NMO is normal.
MATERIAL AND METHODS: We studied prospectively 8 patients with clinically definitive NMO or remitting longitudinal extensive transverse myelitis (LETM) and 8 healthy controls. Ratios of N-acetylaspartate to creatine (Cr) and choline to Cr and the absolute concentrations of the metabolites were measured by chemical shift imaging with a 1H-MR spectroscopy operating at 3T. All patients with clinically definitive NMO and LETM were found to be positive for NMO–immunoglobin G with a commercially available test.
RESULTS: The metabolic pattern of the NAWM of patients with NMO showed no difference compared with age- and sex-matched healthy controls.
CONCLUSIONS: Diffuse white matter damage is absent in NMO.