The current understanding of myelitis in individuals with systemic lupus erythematosus (SLE) includes a distinction between two clinical pictures and pathogenetic mechanisms for the development of myelitis.
- SLE myelitis: a rapid onset severe neurological deficit occurring in the context of clinical and laboratory evidence of active SLE. This has poor prognosis and is thought to have a thrombotic/ischemic etiology.
- Co-existent neuromyelitis optica (NMO): more subacute onset of neurological deficit which is responsive to immunosuppressive therapy but has a relapsing course, often associated with optic neuritis. Markers of SLE activity such as ESR are often within the normal range, and NMO antibody is present. Up to 50% of patients with NMO have a co-existent autoimmune condition, most commonly SLE or Sjogren's syndrome.
In this case, the elevated ESR with C3 and C4 depletion are consistent with active SLE, while absence of NMO antibody makes NMO unlikely.