Conventional and Advanced Imaging in Neuromyelitis Optica

Abstract

SUMMARY:Myelitis and optic neuritis are prototypic clinical presentations of both multiple sclerosis and neuromyelitis optica. Once considered a subtype of multiple sclerosis, neuromyelitis optica, is now known to have a discrete pathogenesis in which antibodies to the water channel, aquaporin 4, play a critical role. Timely differentiation of neuromyelitis optica from MS is imperative, determining both prognosis and treatment strategy. Early, aggressive immunosuppression is required to prevent the accrual of severe disability in neuromyelitis optica; conversely, MS-specific therapies may exacerbate the disease. The diagnosis of neuromyelitis optica requires the integration of clinical, MR imaging, and laboratory data, but current criteria are insensitive and exclude patients with limited clinical syndromes. Failure to recognize the expanding spectrum of cerebral MR imaging patterns associated with aquaporin 4 antibody seropositivity adds to diagnostic uncertainty in some patients. We present the state of the art in conventional and nonconventional MR imaging in neuromyelitis optica and review the place of neuroimaging in the diagnosis, management, and research of the condition. ABBREVIATIONS: AQP4 ϭ aquaporin 4; LESCL ϭ longitudinally extensive spinal cord lesion; MT ϭ magnetization transfer; NMO ϭ neuromyelitis optica

Gray Matter Volume Reduction Is Associated with Cognitive Impairment in Neuromyelitis Optica

“…1,2 Although the brain is traditionally considered to be spared in NMO, 3 recent studies have identified brain lesions in 60% of patients with this condition. 4 In 10% of patients with NMO, the site of brain lesions on MR imaging coincides with high concentrations of the water channel aquaporin 4, 5,6 the target of NMO immunoglobulin G (NMO-IgG). Although several investigations have revealed gray matter impairment in NMO by comparing intergroup differences in the regional homogeneity, 7 amplitude of low-frequency fluctuation, 8 diffusivity, [9][10][11] perfusion, 12 and magnetization transfer ratio, 13 whether GM structural impairment is a feature of NMO is an ongoing debate.…”

Sero-Negative Neuromyelitis Optica

“…These longitudinally extensive spinal cord lesions (LESCLs) are commoner in AQP4 positive patients than those who are negative for the antibody and patient may show short segment T2 hyper-intense lesions on imaging. Delayed imaging after the beginning of symptoms may also result in short segment lesions [12,13].…”

“…The optic nerves may show bilateral involvement, altered signal intensity with posterior extension into the optic chiasma and contrast enhancement [12,13]. In the acute phase, pulse dose methyl-prednisolone therapy is the treatment of choice followed by tapering dose of oral steroid for 2-6 months.…”

Neuromyelitis optica mimics the morphology of spinal cord tumors

“…But the presence of cystic areas, hypointensity in T1-weighted images and the extension of the cervical lesion to the brain stem may suggest NMO. 14 Early diagnosis and treatment of NMO is essential for an accurate prognosis and determination of sequelae. Our findings emphasize the importance of testing for NMO-IgGs in patients diagnosed with intramedul lary tu mors in the spinal cord although 12 percent of patients with a clinical diagnosis of NMO or NMOSD are seronegative for NMO-IgG.…”