According to a medical records analysis, patients with late onset NMOSD experience transverse myelitis more frequently at disease onset in comparison with early onset NMOSD.
In a recent retrospective cohort study of 298 patients diagnosed with neuromyelitis optica spectrum disorder (NMOSD), results showed that patients who developed the disease later (LO-NMOSD) showed more frequent transverse myelitis (TM) at disease onset.1 These findings suggest age of disease onset is associated with clinical characteristics and prognostic outcomes for patients with NMOSD.
All told, patients with LO-NMOSD demonstrated more frequent TM (58.20% vs. 36.00%, P = .007),less frequent optic neuritis (ON) (23.10% vs. 34.80%, P = .031) and brainstem/cerebral attacks (7.50% vs. 18.30%, P = .006) as the first attack in comparison with patients with early onset NMOSD (EO-NMOSD). Tendencies were similar to the initial attack, although the difference was insignificant (P = .091, .083, and .061, respectively) during the disease course.
Senior author Yafang Zhou, MD, PhD, Department of Geriatric Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China, and colleagues wrote, “These above results indicated that there are differences in anatomical susceptibility in patients with different onset age, that the optic nerve and brain were more susceptible in young patients, while the spinal cord was more vulnerable in aged patients. It is possible that this onset-age-dependent anatomical susceptibility may be non-disease-specific and might be related to different vulnerability of blood-brain barrier and blood-spinal cord barrier during aging.”1
Zhou et al added, “Though anatomical preference in adult patients grouped by ages or onset ages has not been well described yet, the preferential impairment of ON in adult patients over pediatric patients in MOGAD is different from what we observed in NMOSD.”
Investigators reviewed 298 medical records of patients diagnosed with NMOSD based on 2015 diagnostic criteria. Patients were divided into 2 groups, with those who were either younger (EO-NMOSD) or older (LO-NMOSD) than 50 years of age at disease onset. Additionally, patients with LO-NMOSD had two subgroups which were relative-late-onset NMOSD (RLO-NMOSD), patients who were between 50 and 70 years at disease onset, and very-late-onset NMOSD, patients aged at least 70 years age at disease onset). Factors investigated with the groups included clinical characteristics, laboratory findings, neuroimaging features, and prognostic outcomes.
In comparison with the EO-NMOSD group, the recurrent course was less frequent in patients with LO-NMOSD (84.2% vs. 74.6%, P = .044). Also, patients with EO-NMOSD showed higher ARR-1 (0.7 [±0.6] vs. 0.6 [±0.5]; P = 0.047) in comparison with the LO-NMOSD group,patients with LO-NMOSD displayed higher Expanded Disability Status Scale (EDSS) score (3.5 vs. 2.5, P < 0.001), higher proportion of motor dysfunction (EDSS ≥ 6) (29.9% vs. 15.9%, P = 0.005) and severe motor dysfunction (EDSS ≥ 8) (12.7% vs 5.5%, P = 0.038) at the last follow up.
Furthermore, patients with VLO-NMOSD demonstrated more frequent TM in comparison with those with RLO-NMOSD (86.7% vs. 56.6%, P = .0242). Patients with VLO-NMOSD had more severe disability as measured by EDSS score at last follow-up (3.0 vs. 5.5, P = .026). Additionally, Patients with VLO-NMOSD showed longer segments of spinal lesions in comparison with the RLO-NMOSD group at first attack (9.0 vs. 5.75, P = .015), and at the last follow-up (10.5 vs 6.0, P = .007).
“Because patients with NMOSD rarely present with a progressive clinical course, disability is generally thought to accumulate from frequent relapses or poor recovery after severe episodes,” Zhou et al noted.1 “In our group, LO-NMOSD patients showed severer disability with shorter disease duration, less relapsing times, and lower relapsing rate (measured by ARR-1) compared to EO-NM. Thus, the higher proportion of transverse myelitis at disease onset and the impaired restorative capacity may partly explain the poorer prognosis of LO-NMOSD.”
Limitations of the study included the retrospective design of the study; therefore, biases were inevitable and sample size was small. In addition, factors such as duration of the disease differences and neuroimaging timing of the evaluation or the cerebrospinal fluid analysis may have influenced the results. The investigators only assessed AQP4-IgG serostatus and did not test on the anti-MOG antibody.
Zhou et al noted, “This study demonstrated that patients with older age of onset exhibit more frequent transverse myelitis, less frequent optic neuritis, fewer NMOSD-typical brain lesions on MRI, longer segments of spinal cord lesions, less frequent relapses, more aggressive disease progress and severer disability. These findings need to be further confirmed in prospective studies with larger sample size and strictly controlled multiple variables.”1