Clinical outcomes and predictive factors related to good outcomes in plasma exchange in severe attack of NMOSD and long extensive transverse myelitis: Case series and review of the literature.

OBJECTIVE: To investigate the predictive factors associated with good outcomes of plasma exchange in severe attacks through neuromyelitis optica spectrum disorder (NMOSD) and long extensive transverse myelitis (LETM). In addition, to review the literature of predictive factors associated with the good outcomes of plasma exchange in central nervous system inflammatory demyelinating diseases (CNS IDDs).
METHODS: Retrospective study in 27 episodes of severe acute attacks myelitis and optic neuritis in 24 patients, including 20 patients with NMOSD seropositive, 1 patient with NMOSD seronegative and 3 patients with LETM. Plasma exchange was performed, reflecting poor responses to high-dose intravenous methylprednisolone (IVMP) therapy. The outcomes of the present study were the functional outcome improvements at 6 months after plasma exchange. The predictive factors of good outcomes after plasma exchange were determined in this cohort, and additional factors reported in the literature were reviewed.
RESULTS: Plasma exchange was performed in 16 spinal cord attacks and 11 attacks of optic neuritis. Twenty patients were female (83%). The median age of the patients at the time of plasma exchange was 41 years old. The median disease duration was 0.6 years. The AQP4-IgG status was positive in 20 patients (83%). Plasma exchange following IVMP therapy led to a significant improvement in 81% of the cases after 6 months of follow up. A baseline Expanded Disability Status Scale (EDSS) score ≤6 before the attack was associated with significant improvement at 6 months (p=0.02, OR 58.33, 95%CI 1.92-1770). In addition, we reviewed the evidence for factors associated with good outcomes of plasma exchange in CNS IDDs, classified according to pre-plasma exchange, post-plasma exchange, and radiological features.
CONCLUSION: Plasma exchange following IVMP therapy is effective as a treatment for patients experiencing a severe attack of NMOSD or LETM. The factors associated with good outcomes after plasma exchange in CNS IDDs are reviewed in the literature. We classified 3 different aspects, including pre-plasma exchange factors, based on minimal disability at baseline, preserved reflexes, early initiation, and short disease duration; post plasma exchange factors, including early improvement or lower disability at last follow up; and radiographic factors, for which the presence of active gadolinium lesions and the absence of spinal cord atrophy seem to be good outcomes for plasmapheresis.