Each of these neuroimmune disorders remain a challenge to diagnose. Only MOG-Ab disease and NMOSD have distinct and defined markers. The diagnostic criteria for the other disorders are neither entirely clear-cut nor universally accepted in medicine (i.e., there appear to be numerous exceptions to every rule). The relationships between each of these disorders are also not well understood (i.e., is each of these disorders a unique disease, or are some of them variants of the same disease?) To arrive at a diagnosis for any one of these disorders, an MRI will need to be done, with and without contrast agent, a spinal tap (lumbar puncture) should be performed, and brain scans will need to be done to rule out MS. If NMOSD is suspected (recurrent TM, ON, recurrent ON, or LETM), the NMO-IgG should be done, and a test for anti-MOG should be done.