Neuromyelitis-optica is a relapsing inflammatory autoimmune condition characterized mainly by acute myelitis and optic neuritis although other criteria exist.
IgG against AQP-4 receptor on the astrocyte foot processes is 76% sensitive and 100% Specific for Neuromyelitis-optica.
Immunosuppression with Azathioprine is 50% effective but never reported to worsen Neuromyelitis-optica.
A 52-year-old-female with history of blindness secondary to bilateral optic neuritis and Myasthenia gravis, in remission, underwent extensive work up for relapsing remitting brain and cervical spine demyelinating lesions and frequent muscle spasms. Initial work up was positive for ANA and DS-DNA but she lacked sufficient diagnostic criteria for SLE. Serum and CSF angiotensin-converting-enzyme, oligoclonal bands, AQP4-IgG, infectious and paraneoplastic panel were negative. Repeat AQP4-IgG titers were elevated despite unchanged neuroimaging. Neuromyelitis-optica was diagnosed; she received pulse corticosteroid therapy and plasma-exchange. She was started on azathioprine two weeks later. After four weeks, she developed paraparesis. MRI showed acute pan-myelitis involving C2 to L2. Repeat AQP4-IgG titers were further elevated.
This is the first reported case of paradoxical fulminant deterioration after starting azathioprine.
AQP4 IgG titer assay revealed significant rise. This potentially indicates a hyperactive immune response to initiation of azathioprine. Clinical course and prior laboratory studies support our hypothesis.