[A clinical analysis of onset of high-risk demyelinating events in patients with neuromyelitis optica].

Objective: To explore the clinical characteristics of the lesions of spinal cord and optic nerve as the onset of neuromyelitis optica (NMO).
Methods: A total of fifty-one patients with myelitis or optic neuritis (ON) as the onset of NMO who hospitalized in our Neurology Department during October 2010 to October 2012 were enrolled in the study. Clinical presentations and MRI findings of the spinal cord and brain were studied.
Results: (1) A total of 26 cases (51.0%) presented with myelitis as the index event, in which 30.8% (8/26) were the longitudinally extensive transverse myelitis (LETM) and 69.2% (18/26) were non-LETM (short segmental myelitis or non-transverse myelitis). Patients with non-LETM as the onset were found to have better prognosis than those with LETM (full recovery ratio was 13/18 vs 2/8, P < 0.05), while shorter recurrence interval of myelitis and higher recurrence frequency of events were shown in patients with non-LETM (11.1 vs 18.6 months, 3 times per year vs once per year, with all P < 0.05). (2) A total of 25 cases (49.0%) presented with ON as the index event with 24.0% (6/25) of unilateral ON and 76.0% (19/25) of bilateral ON. Patients with bilateral ON had more severe visual impairment and shorter first remission period than those with unilateral ON (P < 0.05).
Conclusion: Non-LETM and bilateral ON are the most common index demyelinating events in NMO cases.