New Onset Visual Loss in MOG Antibody Disease

Dear Editor, Myelin oligodendrocyte (MOG) antibody disease is a central nervous system demyelinating disorder which commonly presents as optic neuritis, transverse myelitis or acute disseminated encephalomyelitis (ADEM).[1] Glucocorticoids are the first-line treatment for long-term immunosuppression in MOG antibody disease. Peptic ulcer, diabetes mellitus, hypertension, weight gain, osteopenia, cataracts, glaucoma, and psychosis are well-recognized side effects of corticosteroids. However, central serous retinopathy (CSR) is an underrecognized complication of systemic corticosteroids. Here we report a case of a young male with MOG antibody disease who developed acute visual loss while on oral prednisolone, which was diagnosed as CSR, which resolved after discontinuation of the drug. A 25-year-old male was diagnosed with ADEM due to MOG antibody disease and was treated with pulse methylprednisolone followed by rituximab. He was maintained on oral prednisolone after the pulse therapy. The dose was tapered by 10 mg/day every two months. Four months later, shortly after being tapered to 15 mg/day of prednisolone, he presented with acute blurring of vision in the right eye. On examination, visual acuity in both eyes was 6/6 with a central scotoma in the right visual field. There was no relative afferent pupillary defect, and fundoscopic examination was normal. Visual evoked potential did not show any evidence of optic nerve demyelination. An optical coherence tomography (OCT) of the eye showed subretinal fluid accumulation in the macula of the right eye, confirming the diagnosis of CSR [Figure 1a]. Prednisolone was stopped immediately and spironolactone 25 mg once daily was started. After two weeks of stopping prednisolone and with spironolactone, he had a full visual recovery but developed anorexia, nausea, vomiting, and lethargy. Blood sugar and serum electrolytes were normal. Suspecting steroid withdrawal syndrome (SWS) aldosterone was stopped, intravenous hydrocortisone was administered, and prednisolone was restarted at 5 mg/day. His symptoms resolved by the next day. There was no recurrence of visual symptoms while on low dose of prednisolone and a repeat OCT after one -month showed full resolution of the subretinal fluid [Figure 1b].Figure 1: (a) Optical coherence tomography showing subretinal fluid accumulation (b) Repeat OCT one month after stopping steroids showing complete resolutionCSR is characterized by serous detachment of the neurosensory retina at the macula. Acute CSR is typically unilateral in young patients, with only 4% bilaterality at the time of diagnosis. But it can become chronic and bilateral in up to 40% cases, especially in the elderly.[2] Risk factors for CSR include systemic corticosteroid use, type A personality, hypertension, pregnancy, alcoholism, antibiotics, Helicobacter pylori infection, and bone marrow or organ transplantation. Among these, systemic corticosteroid use has the highest risk of CSR, with an odds ratio of 37.1, followed by pregnancy which has an odds ratio of 7.1.[3] Endogenous hypercortisolism as in Cushing's syndrome can also cause CSR in up to 5% of cases.[4] But CSR per se is a rare complication of systemic corticosteroids with an incidence of only 44.4 per 100,000 person-years.[5] Male gender, middle age, and oral corticosteroids (as opposed to intravenous, inhaled, or topical routes) are associated with an increased risk of corticosteroid-induced CSR. However, there is no clear dose-response relationship for corticosteroid-induced CSR, since it can occur at a very low dose or after a latency of several months.[5] The pathogenesis of corticosteroid-induced CSR is obscure. Steroids can cause platelet aggregation, microthrombi formation, and vasoconstriction leading to increased blood viscosity, altered choroidal perfusion, and vascular permeability. Steroids also inhibit collage formation in the Bruch's membrane altering the ion and water transport in the retinal pigment epithelium. Ultimately there is a breakdown of the posterior blood-retinal barrier leading to subretinal fluid accumulation.[6] Treatment of corticosteroid-induced CSR requires discontinuation of steroids and a favorable outcome can be expected in about 88% of cases. In a prospective observational study, the median period for retinal reattachment after stopping corticosteroids was 49 days (range 32–400 days) and fundus fluorescent angiography showed resolution of leakage at a median of 79 days (range 32–400 days).[7] Adjuvant treatment options which may be added include glucocorticoid antagonists like mifepristone and ketoconazole.[6] Mineralocorticoids are involved in regulating ion and water channels in the retina and choroid, and increased mineralocorticoid signaling is involved in choroidal leakage in CSR.[8] Spironolactone, a mineralocorticoid antagonist has also been successful in treating CSR.[89] The recurrence rate of CSR is about 53% over 10 years.[10] Hence regular follow-up of cases is necessary especially if corticosteroids are continued. Our case also highlights some important issues in the management of MOG antibody disease. Most patients with MOG antibody disease are on glucocorticoids for long-term immunosuppression. Since the presentation of corticosteroid-induced CSR is with visual blurring, it can mimic optic neuritis, which is the most common cause of visual blurring in MOG antibody disease. However, metamorphopsia or micropsia, if present, indicates macular involvement and should raise the suspicion of CSR over optic neuritis. The fundus examination is not sensitive enough to pick up CSR. If the episode is misdiagnosed and treated as optic neuritis with methylprednisolone it will have devastating consequences. Hence, an OCT should be done in patients on corticosteroids to exclude CSR before diagnosing optic neuritis. Secondly, sudden stoppage of corticosteroids may cause SWS. In our case, treatment with spironolactone after stopping prednisolone might have precipitated steroid withdrawal. There is some evidence that a corticosteroid dose reduction by 25%–50% is sufficient for the resolution of CSR without causing SWS.[4] If corticosteroids are abruptly stopped, one should be watchful for symptoms of SWS, because if unrecognized, it may be life-threatening. In such cases, low-dose corticosteroids should be restarted with close monitoring of visual functions. Later on, it may be prudent to taper corticosteroids at a slower rate, since there is a risk of recurrence and progression to chronic CSR, even on low-dose corticosteroids. To conclude CSR should be suspected in cases of acute visual loss while on systemic corticosteroids. Prompt recognition and discontinuation or dose reduction of corticosteroids can lead to good visual recovery. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.