Occurrence of Asymptomatic Acute Neuromyelitis Optica Spectrum Disorder-Typical Brain Lesions during an Attack of Optic Neuritis or Myelitis

Abstract

We aimed to investigate the frequency of asymptomatic acute brain MRI abnormalities accompanying optic neuritis (ON) or myelitis in neuromyelitis optica spectrum disorder (NMOSD) patients with aquaporin-4 antibodies (AQP4-Ab). We reviewed 324 brain MRI scans that were obtained during acute attacks of ON or myelitis, in 165 NMOSD patients with AQP4-Ab. We observed that acute asymptomatic NMOSD-typical brain lesions accompanied 27 (8%) acute attacks of ON or myelitis in 24 (15%) patients. The most common asymptomatic brain abnormalities included edematous corpus callosum lesions (n = 17), followed by lesions on the internal capsule and/or cerebral peduncle lesions (n = 9), periependymal surfaces of the fourth ventricle (n = 5), large deep white matter lesions (n = 4), periependymal cerebral lesions surrounding the lateral ventricles (n = 3), and hypothalamic lesions (n = 1). If asymptomatic NMOSD-typical brain abnormalities were considered as evidence for DIS, while also assuming that the AQP4-IgG status was unknown, the median time to diagnosis using the 2015 diagnosis criteria for NMOSD was shortened from 28 months to 6 months (p = 0.008). Asymptomatic acute NMOSD-typical brain lesions can be accompanied by an acute attack of ON or myelitis. Identifying these asymptomatic brain lesions may help facilitate earlier diagnosis of NMOSD.

A window into the future? MRI for evaluation of neuromyelitis optica spectrum disorder throughout the disease course

“…A retrospective study found that 15% of patients with a myelitis relapse and 8% of patients with optic neuritis relapse had acute asymptomatic brain abnormalities typical of NMOSD. 119 Edematous corpus callosum lesions represented the most common asymptomatic brain lesions, followed by internal capsule and/or cerebral peduncle lesions. Interestingly, the authors found that the median time to diagnosis of NMOSD using the 2015 diagnostic criteria could be significantly shortened from 28 to 6 months if asymptomatic NMOSD brain lesions were included when determining dissemination in space.…”

“… 8 , 9 , 12 The role of longitudinal routine MRI monitoring in NMOSD has not been established, but mounting evidence of subclinical tissue injury raises the question of whether regular follow-up imaging of NMOSD patients can inform treatment decisions in clinical practice. 13 , 14 , 16 , 119 , 126 MRI monitoring of the brain and spinal cord could potentially help treating clinicians identify subclinical inflammation and allow them time to revise the treatment strategy before inflammation progresses to a full attack. However, one of the challenges of routine imaging is that inflammation leading to a clinical relapse may develop rapidly, and unless timed well, MRI may not capture evolving inflammation early enough to prevent its progression.…”

Spinal cord and brain MRI should be routinely performed during follow-up in patients with NMOSD – Yes

“…Asymptomatic lesions in brain and spinal cord MRI have been described in NMOSD patients, 5,6 suggesting that MRI is more sensitive than clinical manifestations. Since brain MRI lesions become more frequent with the duration of the disease, the timing of MRI as well as variations in lesion resolution at follow-up may be important factors for the demonstration of covert tissue alterations in NMOSD patients.…”

“…Kim et al 5 found that asymptomatic NMOSD-typical brain lesions occurred in 8% of acute relapses of optic neuritis (ON) and in 15% of myelitis relapses. Of note, if asymptomatic NMOSD-typical brain abnormalities were considered as evidence for dissemination in space, while assuming that the AQP4-ab status was unknown, the median time to diagnosis using the 2015 diagnosis criteria was significantly shortened from 28 months to 6 months.…”

“…4 Although there is no consensus worldwide about MRI use during follow-up, a recently Latin American NMOSD consensus, based on RAND/UCLA methodology, has recommended routine annual brain MRI use among NMOSD patients after specific treatment as a complementary control at clinical follow-up. 2 Asymptomatic lesions in brain and spinal cord MRI have been described in NMOSD patients, 5,6 suggesting that MRI is more sensitive than clinical manifestations. Since brain MRI lesions become more frequent with the duration of the disease, the timing of MRI as well as variations in lesion resolution at follow-up may be important factors for the demonstration of covert tissue alterations in NMOSD patients.…”