Optic neuritis in Hong Kong: a 1-year follow-up study

Central nervous system neuroinflammatory disorders in Asian/Pacific regions

PURPOSE OF REVIEW

The discovery of aquaporin-4 (AQP4) antibodies with high specificity for neuromyelitis optica spectrum disorder (NMOSD) has induced tremendous changes in the approach and management of central nervous system (CNS) neuroinflammatory disorders. Owing to the increasing availability of the AQP4 antibody assay and evolution of diagnostic criteria for multiple sclerosis and NMOSD, recent studies have reevaluated CNS neuroinflammatory disorders. This review describes recent advances in the understanding of CNS neuroinflammatory disorders in Asian/Pacific regions.

RECENT FINDINGS

Although multiple sclerosis prevalence is lower in Asian countries than in Western countries, the overall clinical features of multiple sclerosis are comparable between these countries. Hospital-based studies have reported that the frequency of NMOSD is higher in Asian populations (22-42%) than in white populations (2-26%). Despite improvements in the AQP4 antibody assay, AQP4 antibodies are not detected in certain patients with NMOSD. Recently, myelin oligodendrocyte glycoprotein (MOG) antibodies have been identified in AQP4 antibody-negative patients with the NMOSD phenotype, and the clinical features differ slightly between MOG antibody-positive patients and AQP4 antibody-positive patients.

SUMMARY

The understanding of CNS neuroinflammatory disorders in Asian/Pacific regions continues to evolve owing to the discovery of new biological markers and recognition of broader clinical phenotypes.

Evaluation of the retinal nerve fiber layer in neuromyelitis optica spectrum disorders: A systematic review and meta-analysis

BACKGROUND

An increasing number of studies have investigated the value of optical coherence tomography in patients with neuromyelitis optica (NMO) spectrum disorders; however, no systematic review has been performed to date. We aimed to systematically review and investigate the possibility of differentiating NMO and multiple sclerosis (MS) via an optical coherence tomography measurement.

METHODS

Electronic databases, including MEDLINE, EMBASE and Web of Science, were systematically searched up to June 2017. A meta-analysis was performed to compare the retinal nerve fiber layer (RNFL) thickness between patients with NMO and MS (or healthy controls).

RESULTS

Twenty-four studies were identified. The meta-analysis demonstrated that the RNFL loss was substantially more severe in NMO than in MS; however, subclinical axon damage was also found in eyes without optic neuritis in NMO. The intereye RNFL difference between eyes with or without optic neuritis was more prominent in NMO (-30.98μm) than in MS (-9.87μm).

CONCLUSION

The RNFL loss was more severe in NMO than in MS, and the intereye RNFL difference between eyes with or without optic neuritis may be useful in differentiating NMO from MS.

Clinical characteristics of optic neuritis in Hong Kong population: 10-year review

PURPOSE

To review the clinical course of adult patients with acute optic neuritis over 10 years in Hong Kong, and the results were compared with other studies among Asian and Caucasian patients.

METHODS

This study retrospectively analysed the clinical features of 38 adult patients (51 eyes) presented with optic neuritis in a Hong Kong hospital over 10 years (2001-2010).

RESULTS

Optic neuritis had a female predominance (68%). The mean age of presentation was 40 years old. Disc swelling (39%) was more common compared to the optic neuritis treatment trial (ONTT). The recovery time ranged from no recovery to 5 years, with a mean of 6.0 months. However, vision continued to deteriorate despite initial improvement in 45% of patients. Only 11.8% of the eyes attained final visual acuity (VA) of 1.0 or better, while 31.4% had VA 0.1 or worse. Multiple sclerosis or neuromyelitis optica only occurred in 10.4% of patients. Three of our patients who did not receive any treatment showed faster recovery than the average.

CONCLUSIONS

Optic neuritis in Hong Kong is mostly a clinically isolated syndrome. Our patients presented at a later age and showed a worse visual outcome. Corticosteroid according to ONTT protocol remained our mainstay of treatment although it did not benefit our patients as much as ONTT study. More work on the long-term prognosis and treatment strategies is worthwhile among Chinese optic neuritis patients.

Change of Th17 Lymphocytes and Treg/Th17 in Typical and Atypical Optic Neuritis

Background

Typical and atypical optic neuritis (ON) are two clinical types of autoimmune inflammatory diseases of the optic nerve that causes acute vision loss, and are difficult to distinguish in their early stages. The disturbance in the balance of Th17 and Treg lymphocytes is thought to play an essential role in these autoimmune inflammatory diseases.

Objectives

To detect the clinical relevance of Th17 and Treg in peripheral blood and the ratio of Treg/Th17 in patients with typical and atypical ON. To determine whether analysis of Th17 and Treg lymphocytes will provides insights into the different disease phenotypes of typical and atypical ON.

Methods

We studied a consecutive series of patients aged 14–70 years who presented to our neurological department with typical ON (n = 30) or atypical ON (n = 33) within 4 weeks of their acute attacks. Routine clinical tests and ophthalmological examination were performed in all patients. Blood samples were collected from untreated patients and from gender- and age-matched healthy controls (n = 30). The proportion of peripheral blood Th17 cells and Treg cells was determined by flow cytometry.

Results

Patients with atypical ON had a higher proportion of Th17 cells than patients with typical ON (3.61±1.56 vs 2.55±1.74, P<0.01) or controls (1.45±0.86, P<0.01). The proportion of Th17 cells in patients with typical ON was also markedly higher than in controls (P<0.01). The mean percentage of Treg cells in atypical ON (6.31±2.11) and typical ON (6.80±2.00) were significantly lower when compared to controls (8.29±2.32, both P<0.01). No significant difference in Treg frequency was observed between typical ON and atypical ON (p>0.05).

Conclusions

The frequency of Th17 cells is higher in atypical ON than typical ON, and patients with atypical ON have a greater imbalance of pro-inflammatory and regulatory cells than patients with typical ON when compared with controls. These changes are indicative of distinct pathological mechanisms and may provide useful information to distinguish typical and atypical ON.

Longitudinal Changes in Retinal Nerve Fibre Layer Thickness after an Isolated Unilateral Retrobulbar Optic Neuritis: 1-Year Results

The objective of this study was to investigate the longitudinal changes in retinal nerve fibre layer (RNFL) thickness 1 year after an episode of unilateral acute optic neuritis. This prospective cohort study recruited consecutive patients with a first episode of isolated, unilateral acute optic neuritis from October 2010 to June 2013. RNFL thickness of the attack and normal fellow eyes was measured by optical coherence tomography on presentation and 3, 6, and 12 months post attack in both the treatment and non-treatment groups. The treatment group consisted of subjects that opted for systemic steroids to hasten recovery time. In 20 subjects, 11 received systemic steroids and 9 were treated conservatively. The baseline RNFL thickness was similar in the attack and fellow eyes (p ≥ 0.4). Progressive RNFL thinning was seen in the attack eye over the 12-month period, with significant differences for baseline versus 3 months; baseline versus 12 months; and 3 versus 12 months (all p < 0.0001). At 12 months, the attack eye had a thinner average RNFL than the fellow eye (100.9 ± 6.1 versus 107.3 ± 5.5 µm; p = 0.002). The 12-month RNFL was similar between the treatment and non-treatment groups (p ≥ 0.6). A single episode of optic neuritis triggered an accelerated, progressive RNFL thinning up to 6 months post attack. Initial treatment with systemic steroids did not seem to alter the degree of RNFL loss at 12 months.