The absence of antibodies in longitudinally extensive transverse myelitis may predict a more favourable prognosis.

BACKGROUND: Isolated first episodes of longitudinally extensive transverse myelitis (LETM) have typically been associated with neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). However, in some cases, serological testing and screening for other aetiologies are negative, a condition referred to as double seronegative longitudinally extensive transverse myelitis (dsLETM). OBJECTIVE: The objective of this study was to evaluate comparative outcomes of dsLETM, MOGAD-LETM and NMOSD-LETM. METHODS: Cohort study of LETM cases seen in the UK NMOSD Highly Specialised Service between January 2008 and March 2022. RESULTS: LETM = 87 cases were identified (median onset age = 46 years (15-85); median follow-up = 46 months (1-144); 47% NMOSD-LETM = 41 (aquaporin-4 antibodies (AQP4-IgG) positive = 36), 20% MOGAD-LETM = 17 and 33% dsLETM = 29). Despite similar Expanded Disability Status Scale (EDSS) at nadir, last EDSS was higher in AQP4-IgG and seronegative NMOSD-LETM (sNMOSD) (p = 0.006). Relapses were less common in dsLETM compared to AQP4-IgG NMOSD-LETM and sNMOSD-LETM (19% vs 60% vs 100%; p = 0.001). Poor prognosis could be predicted by AQP4-IgG (odds ratio (OR) = 38.86 (95% confidence interval (CI) = 1.36-1112.86); p = 0.03) and EDSS 3 months after onset (OR = 65.85 (95% CI = 3.65-1188.60); p = 0.005). CONCLUSION: dsLETM remains clinically challenging and difficult to classify with existing nosological terminology. Despite a similar EDSS at nadir, patients with dsLETM relapsed less and had a better long-term prognosis than NMOSD-LETM.

Comparison of MRI T2-lesion evolution in pediatric MOGAD, NMOSD, and MS.

BACKGROUND: Magnetic resonance imaging (MRI) T2-lesions resolve more often in myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) than aquaporin-4 IgG-positive neuromyelitis optica spectrum disorder (AQP4 + NMOSD) and multiple sclerosis (MS) in adults but few studies analyzed children. OBJECTIVE: The main objective of this study is to investigate MRI T2-lesion evolution in pediatric MOGAD, AQP4 + NMOSD, and MS. METHODS: Inclusion criteria were as follows: (1) first clinical attack; (2) abnormal MRI (⩽6 weeks); (3) follow-up MRI beyond 6 months without relapses in that region; and (4) age < 18 years. An index T2-lesion (symptomatic/largest) was identified, and T2-lesion resolution or persistence on follow-up MRI was determined. RESULTS: We included 56 patients (MOGAD, 21; AQP4 + NMOSD, 8; MS, 27) with 69 attacks. Index T2-lesion resolution was more frequent in MOGAD (brain 9 of 15 [60%]; spine 8 of 12 [67%]) than AQP4 + NMOSD (brain 1 of 4 [25%]; spine 0 of 7 [0%]) and MS (brain 0 of 18 [0%]; spine 1 of 13 [8%]), p < 0.01. Resolution of all T2-lesions occurred more often in MOGAD (brain 6 of 15 [40%]; spine 7 of 12 [58%]) than AQP4 + NMOSD (brain 1 of 4 [25%]; spine 0 of 7 [0%]), and MS (brain 0 of 18 [0%]; spine 1 of 13 [8%]), p < 0.01. Reductions in median index T2-lesion area were greater in MOGAD (brain, 305 mm; spine, 23 mm) than MS (brain, 42 mm [p<0.001]; spine, 10 mm [p<0.001]) without differing from AQP4 + NMOSD (brain, 133 mm [p=0.42]; spine, 19.5 mm [p=0.69]). CONCLUSION: In children, MRI T2-lesions resolved more often in MOGAD than AQP4 + NMOSD and MS which is similar to adults suggesting these differences are related to pathogenesis rather than age.