Periventricular Lesions Help Differentiate Neuromyelitis Optica Spectrum Disorders from Multiple Sclerosis
Abstract
Objective. To compare periventricular lesions in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOsd). Materials and Methods. Sagittal and axial fluid attenuated inversion recovery (FLAIR) sequences of 20 NMOsd and 40 group frequency-matched MS patients were evaluated by two neuroradiologists. On axial FLAIR, periventricular area was characterized as free of lesions/smooth-bordered (“type A”) or jagged-bordered (“type B”) pattern. On sagittal FLAIR, the images were evaluated for presence of “Dawson’s fingers.” Results. Type A pattern was observed in 80% of NMOsd patients by Reader 1 and 85% by Reader 2 but only in 5% MS patients by either Reader. Type B was seen in 15% NMOsd patients by Reader 1 and 20% by Reader 2 and in 95% MS patients by either Reader. Dawson’s fingers were observed in no NMOsd patients by Reader 1 and 5% by Reader 2. In MS, Dawson’s fingers were seen in 92.5% patients by Reader 1 and 77.5% by Reader 2. The differences in periventricular patterns and Dawson’s finger detection between NMOsd and MS were highly significant (P < 0.001). Conclusions. Dawson’s fingers and “jagged-bordered” periventricular hyperintensities are typical of MS and almost never seen in NMOsd, which suggests a practical method for differentiating the two diseases.
1. Introduction
Neuromyelitis optica (NMO) was originally conceived as a disease with predominantly opticospinal predilection, but recent studies revealed brain involvement on MRI in up to 80% of patients [1]. Some brain lesions of NMO have distinct enhancement patterns [2, 3] and lesion morphology [4, 5], but no specific set of radiologic criteria has been validated for NMO.
Periventricular lesions have been reported in NMO [1, 6–8] and linear anterior periventricular linear lesions have been noted to be characteristic of NMO [8]. In MS, periventricular hyperintensities are common and radial callosal lesions—“Dawson’s fingers”—are a helpful radiologic clue to this diagnosis. Dawson’s fingers are elongated, flame-shaped, hyperintense lesions best seen on sagittal FLAIR images. They are oriented along subependymal veins and thus are perpendicular to the walls of lateral ventricles [9, 10]. Pathologically, Dawson’s fingers correspond to areas of perivenous inflammation. We hypothesized that radiographic evidence of perivenous inflammation (Dawson’s fingers or “jagged-bordered” hyperintense signal) is absent or rare in NMO and that examination of periventricular white matter may therefore help to differentiate NMOsd from MS.
2. Materials and Methods
In the NMOsd group, we included only patients with a history of recurrent optic neuritis and/or longitudinally extensive transverse myelitis and seropositivity for anti-AQP4 antibody. All adult NMOsd patients fulfilling the above criteria, who were referred by the NYU MS Center physicians (IK, JH) to the NYU Department of Radiology for brain MRI examination from January 2007 to February 2012, were included in the study. We excluded patients without the MR sequences necessary for the radiological analysis or history of relapse within 8 weeks of MRI. NMOsd subjects were group frequency matched with their two nearest alphabetical neighbours from the NYU MS Clinic who had diagnosis of MS (2010 McDonald criteria) and similar age (±2 years) and disease duration (±2 years) at the time of brain MRI.
The study was approved by institutional review board of the NYU School of Medicine.
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