No MRI evidence of cortical lesions in neuromyelitis optica.
Calabrese, Massimiliano MD; Oh, Mi Sun MD; Favaretto, Alice MD; Rinaldi, Francesca MD; Poretto, Valentina MD; Alessio, Sara MD; Lee, Byung-Chul MD, PhD; Yu, Kyung-Ho MD, PhD; Ma, Hyeo-Il MD, PhD; Perini, Paola MD; Gallo, Paolo MD, PhD
79(16):1671-1676, October 16, 2012.
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Background: Neuromyelitis optica (NMO) is a severe inflammatory demyelinating disease of the CNS in which a pathogenic role of anti-aquaporin-4 (AQP4) antibodies has been suggested. Although AQP4 is expressed in human cortex, recent histologic studies have failed to find any evidence of cortical demyelination in NMO.
Objective: To evaluate, in vivo, the occurrence of focal and diffuse cortical pathology in NMO.
Methods: We studied 30 patients with NMO, 30 patients with relapsing-remitting multiple sclerosis (RRMS), and 30 normal controls (NC). RRMS and NC were age- and gender-matched to NMO. The presence of cortical lesions (CLs) was evaluated on double inversion recovery sequence and cortical thickness (CTh) by the application of Freesurfer on 3 volumetric fast field echo T1-weighted images.
Results: No CL was observed in NC or in NMO, while 83 CLs were identified in 20/30 (66.7%) patients with RRMS. Although NMO did not differ from NC in the global CTh, a mild thinning was observed in some cortical areas (postcentral [p = 0.018], precentral [p = 0.009], and calcarine [p = 0.015] gyri) and in the thalamus (p = 0.036). Global and regional cortical thickness was significantly decreased in RRMS compared to both NMO and NC.
Discussion: Our in vivo data further suggest that the immune-mediated pathologic process occurring in NMO spares most of the cortex. NMO differs from multiple sclerosis, where CLs and atrophy are frequently found, even in early disease phases. Thus, MRI analysis of the cortex may be a potential diagnostic tool, especially in ambiguous cases.
GLOSSARY: AQPR: aquaporin-4
CL: cortical lesion
CTh: cortical thickness
DIR: double inversion recovery
ETL: echo train length
FLAIR: fluid-attenuated inversion recovery
FOV: field of view
GM: gray matter
MS: multiple sclerosis
NC: normal control
NMO: neuromyelitis optica
RRMS: relapsing-remitting multiple sclerosis
TE: echo time
TI: inversion time
TR: repetition time
WM: white matter.
(C)2012 American Academy of Neurology