Brain Lesions May Serve as Diagnostic Criteria for Neuromyelitis Optica
2011;19(8):13.
A majority of patients with neuromyelitis optica also experience disease-specific brain lesions that could help distinguish neuromyelitis optica from multiple sclerosis.
MONTREAL—Imaging studies of patients with neuromyelitis optica (NMO)–spectrum disorders reveal that effects of the aquaporin-4 (AQP4) autoantibody, a marker of the disease, may extend beyond the spinal cord and optic nerve, according to researchers. MRI findings of these disease-specific lesions may make it possible to differentiate between NMO and multiple sclerosis (MS).
Jose A. Cabrera-Gomez, MD, PhD, of the Multiple Sclerosis Clinic International Neurologic Restoration Center and Cuban Multiple Sclerosis Society in Havana, and Ilya Kister, MD, from the New York University School of Medicine, presented their findings at the 25th Annual Meeting of the Consortium of Multiple Sclerosis Centers.
“Antibody to aquaporin-4 (AQP4) is a marker of relapsing NMO with specificity that approaches 100%,” the authors wrote. “Since AQP4 is distributed widely throughout the brain, especially in the ependyma and microvessels, one might expect that NMO would affect not only spinal cord and optic nerves, but brain as well.”
Frequency of Brain Abnormalities in Patients With NMO
To examine the extent of brain involvement in NMO, the researchers reviewed 18 case series (involving approximately 500 patients) that used MRI to document brain abnormalities in patients with NMO-spectrum disorders. The cases were divided into three groups: adult NMO (10), pediatric NMO (5), and anti-AQP4–positive patients (4).
“The frequency of brain abnormalities ranged from 43% to 100%,” Drs. Cabrera-Gomez and Kister reported. Differences in disease expression across ethnic groups, varying time from symptom onset to brain MRI, and methodological differences could contribute to this wide range of findings, they noted.
The authors reported finding striking convergent findings across multiple research groups. “Brain lesions on MRI are very common in NMO and are seen in the majority of patients with prolonged disease duration,” Dr. Lister told Neurology Reviews. “Certain lesion types appear to be typical for NMO and atypical for MS and these could potentially be useful to differentiate NMO from MS.” Lesion types that were typical of NMO included callosal/septal interface lesions, Balo-like lesions in the pons, and cavitary lesions in the occipital lobe. The researchers also noted that AQP4-seropositive patients were more likely to have brain lesions.
Can MRI Findings Differentiate Between NMO and MS?
“Brain lesions are seen in many NMO patients at onset of the disease, and in the majority of NMO patients on follow-up imaging,” the investigators wrote. This study’s findings and the discovery of NMO-specific lesions could lead to the development of diagnostic criteria for the disease.
“We advocate for systematic, prospective, multicenter studies to further characterize evolution of brain lesions in NMO and development of consensus criteria of brain MRI findings that could assist in differentiating NMO from MS,” the authors stated. This entails developing criteria that incorporate both positive brain MRI findings (“typical NMO lesions/high positive predictive value”) and negative brain MRI findings (“atypical in NMO/high negative predictive value”). “Studies are needed to determine sensitivity and specificity of various brain MRI findings for diagnosis of NMO,” said Dr. Lister. “A substantial minority of NMO patients have brain abnormalities that fulfill Barkhoff criteria for dissemination in space in MS. Thus, current MRI criteria for MS cannot be used to definitively differentiate MS from NMO.”
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