Role of Plasma Exchange in the Management of Pediatric Optic Neuritis With Antibodies Against Myelin Oligodendrocyte Glycoprotein

Update on pediatric optic neuritis

PURPOSE OF REVIEW

To summarize recent developments in the classification, investigation and management of pediatric optic neuritis (PON).

RECENT FINDINGS

A recent surge in interest surrounding antibodies to myelin oligodendrocyte glycoprotein antibody (MOG-Ab) has instigated a paradigm shift in our assessment of children with PON. This serological marker is associated with a broad spectrum of demyelinating syndromes that are clinically and radiologically distinct from multiple sclerosis (MS) and aquaporin-4 antibody positive neuromyelitis optica spectrum disorder (AQP4+NMOSD). Optic neuritis is the most common presenting phenotype of MOG-Ab positive-associated disease (MOG+AD). MOG-Ab seropositivity is much more common in the pediatric population and it predicts a better prognosis than MS or AQP4+NMOSD, except in the subset that exhibit a recurrent phenotype.

SUMMARY

A better grasp of MOG+AD features and its natural history has facilitated more accurate risk stratification of children after a presenting episode of PON. Consequently, the initial investigation of PON has broadened to include serology, along with neuroimaging and cerebrospinal fluid analysis. Acute treatment of PON and chronic immunotherapy is also becoming better tailored to the suspected or confirmed diagnoses of MS, AQP4+NMOSD and MOG+AD.

Prognostic indicators of improvement with therapeutic plasma exchange in pediatric demyelination

OBJECTIVES

To determine the safety and clinical benefit of therapeutic plasma exchange (TPE) as rescue therapy in children with acute inflammatory demyelinating CNS syndromes and to identify baseline prognostic indicators of treatment improvement.

METHODS

This single-center retrospective pediatric cohort included all consecutive patients admitted to our hospital over the period from 2003 to 2017 because of a steroid-refractory acute CNS event presumed to be inflammatory who required TPE. Functional status assessment to identify improvement included the following performance category scales: visual outcome, bladder control, gait, and Expanded Disability Status Scale (EDSS). These assessments were performed before and after TPE in every patient.

RESULTS

Sixty-five children requiring TPE to treat 78 CNS attacks were included for analysis. Median age at TPE was 10.5 years (1.9-18 years); 45% were girls. Seropositivity (aquaporin-4 water channel-immunoglobulin G [IgG] or myelin oligodendrocyte glycoprotein-IgG) was found in 20 of 42 (48%) patients. Attack phenotypes leading to TPE were optic neuritis (ON) in 42%, longitudinally extensive transverse myelitis (LETM) in 31%, ON + LETM in 15%, and other combined syndromes in 11%. Overall, moderate to marked neurologic improvement was observed in 72% of children at the end of TPE and in 88.5% at 6 months of follow-up. Lower baseline scores on the EDSS, visual outcome, and gait scales were found to be independent prognostic indicators of treatment benefit. Sex, age at onset and at TPE, attack phenotype, disease duration, and time from attack onset to TPE initiation were not significantly associated with treatment outcome. Adverse events were observed in 31 of 524 (5.9%) procedures, being severe in 4.

CONCLUSIONS

TPE was an effective rescue therapy associated with functional improvement. No therapeutic window for TPE initiation was identified in this pediatric cohort. Overall frequency of adverse events was low; however, serious events should be anticipated and avoided.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for children with acute inflammatory demyelinating CNS syndromes, TPE leads to functional improvement.