Transorbital Sonography for Monitoring Neuromyelitis Optica: a Case Report

A patient with an atypical neuromyelitis optica (NMO) is described. Besides clinical, imaging, and laboratory data, we monitored the clinical course by using transorbital sonography (TOS). Currently, only few data about ultrasound role in monitoring optic neuritis in multiple sclerosis are available, with unconclusive results. Data about TOS in NMO are lacking. A 23-year-old woman complained of acute, painful, and severe visual loss in left eye. Visual evoked potentials (VEPs) showed unilateral prolongation of P100 latency. Antibodies directed against aquaporin 4 (AQP4-IgG) were positive. Brain MRI imaging was unremarkable; spinal MRI revealed a longitudinal syringomyelia cavity extending from T7 to T10. The patient was diagnosed with NMO. She was treated with intravenous prednisolone with rapid recovery. At admission, TOS showed an enlargement of ONSD on the left side, which subsequently decreased up to normalization; at successive control at 120 days, when the patient experienced a relapse of ON with papillitis, both unilateral ONSD enlargement and optic disc elevation (ODE) were observed that normalized after immunomodulatory therapy. She did not experience any relapse in the following three years. In our case, serial TOS monitoring was an adjuvant diagnostic tool of clinical course of recurrent ON and papillitis in NMO. Further cases are needed to demonstrate accuracy of TOS in monitoring ON associated with poor visual outcomes.