Objective:

To present the successful therapeutic use of intravenous (IV) eculizumab in a pediatric patient with acute aquaporin-4 (AQP4) IgG positive neuromyelitis optica spectrum disorder (NMOSD). 

Background:

NMOSD is an immune-mediated disorder of the central nervous system in which pathogenic IgG autoantibodies against the AQP4 water transport channel produce astrocyte, myelin, and neuronal injury through complement-mediated cytotoxicity. First-line treatment of an acute flare of NMOSD includes high dose IV steroids often combined with plasma exchange (PLEX). Eculizumab is a monoclonal antibody that inhibits complement-mediated cytotoxicity and was reported to mildly improve an adult with acute AQP4-IgG seropositive NMOSD failing IV methylprednisolone (IVMP) and PLEX. To our knowledge, there are no reports of eculizumab used in children with an acute NMOSD relapse. 

Design/Methods:

Case report and literature review 

Results:

A 12-year-old male presented with emesis, bulbar weakness, paresthesias, limb weakness, gait instability, urinary retention, and respiratory failure requiring intubation. His extensive workup was negative except for cerebrospinal fluid analysis showing mild pleocytosis and an MRI brain showing a non-enhancing T2 hyperintense lesion in the dorsal medulla. AQP4 IgG titers were positive (serum >1:100,000 [reference <1:5], CSF >1:2,048 [reference <1:2]). He received a 5-day course of IVMP 30 milligrams (mg)/kilogram/day and 5 sessions of PLEX. The patient had minimal improvement, instead developing new numbness and tremor. With worsening symptoms, he was initiated on eculizumab. Eculizumab was administered per the pediatric dosage recommended for atypical hemolytic uremic syndrome: two weekly doses of 600 mg as an induction course, followed by initiation maintenance dosage of 900 mg at week 3 and every 2 weeks thereafter. Our patient demonstrated rapid stabilization and improvement, returning near baseline within months except for mild right-sided residual weakness and fatigue which is gradually improving.

Conclusions:

This case demonstrates the potential utility of eculizumab for the acute treatment of pediatric AQP4-IgG seropositive NMOSD relapses.