Atypical Cerebral MRI Imaging Associated Related to NMOSD

Neuromyelitis Optica Spectrum Disorders (NMO-SD) are a group of aggressive auto-inflammatory central nervous system affections which were considered to be a particular form of multiple sclerosis for a long time before the discovery of AQP4 antibodies. Brain magnetic imaging holds a primordial place in the diagnosis process. NMO-SD lesions are classically located in the area postrema, peri-ependymal regions and the spinal cord and in the retro-chiasmatic section of the optical nerve. The localization of these lesions correlates with the classical clinical signs associated with NMO SD which are hiccups and vomiting, and bilateral visual impairment. Some rare descriptions of atypical demyelinating lesions associated with NMO-SD were made. An eighteen years old girl presented headaches four weeks before admission, associated with daily vomiting. One week following the onset of symptoms, she developed a rapidly evolving bilateral visual loss. The patient initially consulted with an otorhinolaryngologist and was subsequently surgically treated for pansinusitis. Clinical examination found hypoesthesia on the left side and an impaired visual acuity (only hand movements could be seen). MRI showed extreme lesions with bilateral neuritis optica and extensive demyelinating lesions in the peri-acqueducal and periventricular regions, the mamillary bodies, the quadrigeminal tubercles and the chiasma associated with a cervical lesion. Extensie blood work was performed with research of AQP4 antibodies and neuronal antibodies. Cerebro-spinal fluid (CSF) was also investigated with the research of intrathecal synthesis. Neuronal antibodies came back negative, and the patient was AQP4 seronegative but CSF study found evidence of intrathecal synthesis in favor of an inflammatory activity. As differential diagnosis was made with pseudo-tumoral multiple sclerosis, she was initially treated with a 7-days methylprednisolone intravenous administration (7 g in total) with no response. She was then treated with plasmapheresis sessions showing spectacular improvement with complete visual recovery. The patient is currently under a rituximab protocol and was left on a minimal daily methylprednisolone intake of 20mg and hasn't shown clinical relapse since the initial signs although control MRI has shown some active lesions, albeit the activity has notably decreased. In the case of this patient, differential diagnosis of pseudo-tumoral multiple sclerosis was made, however as corticosteroid