Chiasmatic lesions on conventional magnetic resonance imaging during the first event of optic neuritis in patients with neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein‐associated disease in a Latin American cohort

Abstract

Background and purpose Optic neuritis (ON) is often the initial symptom of neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein‐associated disease (MOGAD). We aimed to compare the frequency and pattern of chiasmatic lesions in MOGAD‐related ON (MOGAD‐ON) and NMOSD‐related ON (NMOSD‐ON) using conventional brain imaging (magnetic resonance imaging [MRI]) in Latin America (LATAM). Methods We reviewed the medical records and brain MRI (≤30 days from ON onset) of patients with a first event of MOGAD‐ON and NMOSD‐ON. Patients from Argentina (n = 72), Chile (n = 21), Ecuador (n = 31), Brazil (n = 30), Venezuela (n = 10) and Mexico (n = 82) were included. Antibody status was tested using a cell‐based assay. Demographic, clinical, imaging and prognostic (as measured by the Visual Functional System Score [VFSS] of the Expanded Disability Status Scale) data were compared. Results A total of 246 patients (208 NMOSD and 38 MOGAD) were included. No differences were found in gender and ethnicity between the groups. We observed chiasmatic lesions in 66/208 (31.7%) NMOSD‐ON and in 5/38 (13.1%) MOGAD‐ON patients (p = 0.01). Of these patients with chiasmatic lesions, 54/66 (81.8%) and 4/5 had associated longitudinally extensive optic nerve lesions, 45/66 (68%) and 4/5 had bilateral lesions, and 31/66 (47%) and 4/5 showed gadolinium‐enhancing chiasmatic lesions, respectively. A positive correlation was observed between VFSS and presence of bilateral (r = 0,28, p < 0.0001), chiasmatic (r = 0.27, p = 0.0001) and longitudinally extensive lesions (r = 0,25, p = 0.0009) in the NMOSD‐ON group, but no correlations were observed in the MOGAD‐ON group. Conclusions Chiasmatic lesions were significantly more common in NMOSD than in MOGAD during an ON attack in this LATAM cohort. Further studies are needed to assess the generalizability of these results.

Frequency of NMOSD misdiagnosis in a cohort from Latin America: Impact and evaluation of different contributors

“…However, suggestive lesions in patients who present ON, myelitis, or cerebral/cortical syndromes may help to distinguish both conditions, especially when these symptoms cannot be differenced at presentation. 23,28,36…”

MRI to differentiate multiple sclerosis, neuromyelitis optica, and myelin oligodendrocyte glycoprotein antibody disease

“…Spinal lesions were similarly rare in MOGAD (0%) as MS (4.4%) and AQP4‐ab‐positive NMOSD (0%) 118 . The appearance of asymptomatic lesions was not related to a higher risk of subsequent relapse at follow‐up, but further studies are needed 105 . Shah et al.…”

“…118 The appearance of asymptomatic lesions was not related to a higher risk of subsequent relapse at follow-up, but further studies are needed. 105 Shah et al found that asymptomatic optic nerve enhancement occurred in 16.8% of AQP4-ab-positive NMOSD patients with preceding ON and new asymptomatic enhancement was observed only in 1.8% of patients. 119 A subanalysis from the inebilizumab study (N-MOmentum randomized placebo-controlled trial) in NMOSD patients found that 51%, 3%, and 18% of MRI showed asymptomatic optic nerve, brain, and spinal cord gadolinium-T1 MRI enhancement during an interattack surveillance MRI (in the absence of adjudicated attacks), respectively.…”

“…103,104 Typically, AQP4-ab-positive NMOSD is associated with lesions in the posterior segment, often with longitudinally extensive lesions (spanning greater than half of the length of the optic nerve) and gadolinium enhancement in the acute phase or chiasmal involvement of the optic pathway. 2,49,105 Additionally, simultaneous or sequential involvement of both optic nerves on MRI is highly suggestive of NMOSD and bilateral optic nerve lesions were reported in up to 46.6% of NMOSD-ON patients at disease onset. 106 Asymptomatic ON lesions have been reported recently in a preliminary analysis from the N-Momentum trial (27% experienced at least one new asymptomatic gadolinium-T1 MRI-enhancing lesion).…”

“…These lesions are usually found in the anterior segment of the optic nerve and typically spare the optic chiasm and retrochiasmatic optic tracts. Recently, optic chiasm involvement was reported significantly more frequent in NMOSD‐ON (31.7%) than MOGAD‐ON (13.1%) and MS 105 . However, optic nerve head swelling was observed in over half of the MOGAD‐ON patients ( n = 19), whereas only 1 AQP4‐ab‐positive NMOSD‐ON patient ( n = 13) and none of the MS‐ON (n = 11) presented this pattern, 103 being an important characteristic for distinguishing MOGAD from other inflammatory diseases 97 .…”