## 7 Treatment Methods  
Intravenous methylprednisolone (IVMP) treatment inhibits inflammatory cascade reactions by inhibiting pro-inflammatory cytokine production, increasing anti-inflammatory cytokine levels, suppressing T cell activation by inducing T cell apoptosis, and causing impairment of granulocyte migration and downregulation of expression of cell adhesion molecules, receptors, and matrix metalloproteinase [181]. IVMP could significantly improve visual acuity and facilitate retention of the thickness of the retinal nerve fibre [7; 182].  
Corticosteroids are used to treat acute inflammation in NMO. A high dose of corticosteroids suppresses the acute phase of the inflammatory response [183]. A high dose of corticosteroid, solumedrol, is given to NMO patients with acute demyelination. Corticosteroids can cause immunosuppression and anti-inflammation by reducing peripheral lymphocytes and inflammatory cytokines [184].  
In cases of poor or minimal response to steroid pulse therapy, apheres therapies are recommended, wherein the pathogenic antibodies and proteins are removed from the patient's blood circulation [185; 186]. Plasma exchange (PLEX) and immunoadsorption (IA) are the two major apheresi therapies used in NMOSD. PLEX involves the removal of AQP4 autoantibodies and proinflammatory cytokines and regulates the proliferation and function of lymphocytes [187]. PLEX has side effects, including infections due to invasive techniques, hypotension, coagulopathies, and electrolyte imbalances [9]. In combination with IVMP, PLEX therapy confers better improvement in cases of severe spinal impairment and visual acuity in ON [188]. In cases such as corticosteroid-resistant relapses and NMO patients, PLEX treatment can be given in addition to IVMP to suppress severe spinal attacks [189] and to improve visual acuity in ON [190].  
IA is an alternative apheresis technique that deals with albumin and clotting factors [191]. Both the PLEX and IA are effective treatments for NMOSD with myelitis [192]. Studies indicate that in case of severe relapse of NMOSD, the combination of corticosteroids and apheresis therapy exhibits better outcomes [193; 194]. Thus, instead of providing a single therapy at a time, combinatorial therapies might be considered a better treatment procedure in case of an acute attack of NMOSD.  
Apart from the treatment mentioned above, steroid therapy, apheresis therapies, and the intravenous immunoglobulins (IVIg) method can be used to treat NMOSD attacks. IVIg exerts immunomodulatory effects such as modulation of immune effector cells, blocking cellular receptors, and neutralizing cytokines, complementing molecules and autoantibodies [195]. IVIg reduces the relapse rate in NMOSD and can be used as a treatment procedure for NMOSD patients with repeated infections [9]. In NMOSD patients, IVIg treatment has proved promising as it could reduce AQP4 antibody levels [196] and neutralize the B cell activating factor at the onset of NMOSD [197]. Furthermore, IVIg interferes with administered IgG through antigen recognition, suppression of T cell activation, and downregulation of cytokine networks and adhesion molecules. To conclude, when there is low or insignificant remission in the case of corticosteroid therapy and apheresis therapies, IVIg could be an alternative treatment option [198].