In recent years, not only the incidence of brain demyelinating disease has increased, but also it seems that the world is facing new forms of autoimmune diseases of the brain. Distinguishing these diseases from each other is very important, since each requires a different treatment. The new criteria that were put forward in 2015 were meant to pave the way for better diagnosis of these diseases called neuromyelitis optica spectrum disease (NMOSD). However, too much emphasis on the criteria based on the convergence and association of radiological findings with the clinical symptoms actually causes confusion in the diagnosis. Here, the case of a 16-year-old child suffering from optic neuritis has been discussed. Her cervical magnetic resonance imaging (MRI) revealed longitudinal extensive transverse myelitis (LETM); however, the patient had no symptoms of the spinal cord's involvement. According to the 2015 criterion, the diagnosis of NMOSD cannot be accepted for this patient. Therefore, this case report emphasizes on the modification of the existing criterion. •A case of a 16-year old child suffering from optic neuritis is discussed.•His cervical MRI revealed longitudinal extensive transverse myelitis.•The patient had no symptoms of spinal cord involvement.•According to 2015 criterion, the diagnosis of NMOSD cannot be accepted for this patient.•This case report emphasizes on the modification of the existing criterion.