1. Neuromyelitis Optica: Looking at the Brain for Clues
Christie M Lincoln MD, Kellen Carril MD, Rola Mahmoud MD, Peter Fata MD, Darshan Variyam MD, George Hutton MD, Tomas Uribe MD
ASNR 2016 Washington, DC
eP-82
2332
Neuromyelitis Optica: Looking at the Brain for Clues

2. Disclosures:
Christie M Lincoln MD: None
Kellen Carril MD: None
Rola Mahmoud MD: None
Peter Fata MD: None
Darshan Variyam MD: None
George Hutton MD: None
Tomas Uribe MD: None

3. Neuromyelitis Optica: Looking at the Brain for Clues
Christie M Lincoln MD, Kellen Carril MD, Rola Mahmoud MD, Peter Fata MD, Darshan Variyam MD, George Hutton MD, Tomas Uribe MD
Baylor College of Medicine, Houston, Texas
BACKGROUND
Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease with clinical symptoms mostly related to optic neuritis and transverse myelitis. At times, it can be difficult to diagnose as it can mimic other inflammatory processes with opticospinal manifestations such as multiple sclerosis and sarcoidosis. Due to the location of aquaporin-4, the most abundant water channel in CNS astrocytes (Figure 1), there are classic imaging patterns of the brain lesions in NMOSD that can assist in diagnosis. Early diagnosis is exceptionally important as prompt initiation of appropriate immunosuppressive treatment can prevent attack related disability in NMOSD.
Figure 2 (left): Axial postcontrast T1 orbital image shows right optic nerve enhancement.
Figure 3 (right): Sagittal postcontrast T1 shows long segment spinal cord enhancement.
Figure 4: Axial FLAIR demonstrates hyperintensity in the right hypothalamus.
Figure 5: Axial FLAIR with hyperintensity within the left cerebral peduncle and tegmentum.
Figure 6: Axial T1 postcontrast shows ring enhancing lesion at the left posterolateral medulla close to the area postrema.
Figure 7: Periependymal hyperintensity at the right upper atria on axial FLAIR.
Based on the classical imaging patterns provided by Kim et al, we found that a vast majority of our case cohort were representative of NMOSD. Our study showed patients with periependymal lesions, which are diencephalic lesions surrounding the third ventricle and cerebral aqueduct (5/28, 17%, Figures 4 and 5), dorsal brainstem lesions adjacent to 4th ventricle (13/28, 46%, Figure 6), and lesions surrounding lateral ventricles including corpus callosum (15/28, 53%, Figure 7).
Figures 8a (left) and 8b (right): “Cloud like” contrast enhancement involving the entire corpus callosum (blue arrows).
Figure 8b also shows leptomeningeal enhancement at the level of the nodulus (white arrow).
Several brain lesions in our patient cohort demonstrated either poorly marginated, subtle, multiple patchy or ‘cloud-like’ and linear ependymal enhancement patterns (5/28, 18%, Figure 8 and 9). We had one case of leptomeningeal enhancement (1/28, 3%, Figure 8b).
Figure 9a (left): Left frontal linear periependymal enhancement (blue arrow) and enhancement of the splenium of the corpus callosum (white arrow).
Figure 9b (right): Left atrial and temporal periependymal enhancement.
Our retrospective review revealed 2 cases with cortical based lesion in the precentral gyrus ( Fig 9), which is not classified under the typical imaging pattern.
Though autoantibodies to aquaporin-4 are specific for NMOSD, the sensitivity is only 60-80%, as was the case with 20 of the 28 patients (71%). The sensitivity is lower in those on immunosuppressive therapies. In some cases, this changed the initial multiple sclerosis diagnosis.
Figures 9a (left) and 9b (right): Cortical hyperintensity at the left precentral gyrus cortex (blue arrow) on axial and sagittal FLAIR images. Subcortical white matter hyperintensity on the contralateral side (white arrow).
The discovery of aquaporin-4 IgG assays has shifted emphasis upon the significance of brain lesions especially those in close proximity to aquaporin receptors, leading to overexpression. In our study, 4 of 28 (14%) patients harbored no brain finding and all had aquaporin-4 IgG positive, which is a very small percentage compared to those with intracranial lesions.
Figure 1: Illustration of the sagittal brain with turquoise outline of the aquaporin-4 sites.
CONCLUSIONS
Despite brain imaging findings considered a part of the supportive criteria for diagnosis of neuromyelitis optica spectrum disorder, a knowledge of the variety of intracranial imaging manifestations can assist in diagnosis. Thereby, resulting in early initiation of treatment and prevention of attack related disability.
METHODS
Two board certified radiologists each with certificate of added qualification in neuroradiology retrospectively reviewed the brain MRIs of 28 subjects in our case series diagnosed with NMOSD either with aquaporin-4 IgG positivity or utilizing recently revised serum, clinical and/ or imaging criteria.
REFERENCES
Kim HJ, Paul F, Lana-Peixoto, et al. MRI characteristics of neuromyelitis optica spectrum disorder. Neurology. 2015; 84:
Pittock SJ, Lucchinetti CF. Neuromyelitits optica and the evolving spectrum of autoimmune aquaporin-4 channelopathies: a decade later. Ann NY Acad. Sci. 2016; 1366:
Pittock SJ, Weinshenker BG, Lucchinetti CF, et al. Neuromyleitis Optica brain lesions localized at sites of high aquaporin 4 expression. Arch Neurol. 2006; 63:
Wingerchuk DM, Lennon VA, Pittock SJ, et al. Revised diagnostic criteria for neuromyelitis optica. Neurology. 2006; 66:
Pittock SJ, Lennon VA, Krecke K, et al. Brain abnormalities in neuromyelitis optica. Arch Neurol. 2006; 63:
RESULTS
Our case cohort included a high number of females (23/28, 82%) and either blurry and/or painful vision as the most common presenting symptom (14/28, 50%). A few case presentations were solely related to transverse myelitis (6/28, 21%). There were several cases wherein a combination of symptoms related to optic neuritis and transverse myelitis manifested prior to diagnosis (6/28, 21%, Figures 2 and 3).
The presentations of two of the 28 cases were unavailable as diagnosis was made at different institutions.