AQP4 and vitamin B12 deficiency: A further 25 patients with definite etiologies were also excluded: AQP4-IgG-associated (n = 4), MOG-IgG-associated (n = 3), GFAP-IgG-associated (n = 3), CIS (n = 3), infectious conditions [tuberculosis (n = 3), HSV (n = 1), and syphilis (n = 1)], surgical injury (n = 1), spinal ischemia (n = 1), tumor (n = 1), compression (n = 2) and vitamin B12 deficiency (n = 2).