Clinical and Visual Outcomes of Dysthyroid Optic Neuropathy After Surgical Orbital Decompression.

Background: Current guidelines suggest high-dose steroids as first-line treatment for dysthyroid optic neuropathy (DON). When steroids fail, decompressive surgery is mandatory. Methods: We conducted a single-center, retrospective cohort study in a tertiary care combined Thyroid-Eye clinic in Milan, Italy. We studied 88 orbits of 56 patients that were submitted to surgical orbital decompression to treat DON from 2005 to 2020. Of these, 33 orbits (37.5%) underwent surgery as first-line treatment for DON whereas the other 55 (62.5%) were decompressed after being unresponsive to very high-dose steroids. Previous orbital surgery, concurrent neurological or ophthalmologic diseases, or incomplete follow-up were considered as exclusion criteria from this study. Surgery was considered successful if no further decompression was needed to preserve vision. Pinhole best corrected visual acuity (p-BCVA), color sensitivity, automated visual field, pupil reflexes, optic disk and fundus appearance, exophtalmometry, and ocular motility were studied before and after surgery (1 week, 1, 3, 6, and 12 months). Activity of Graves' Orbitopathy (GO) was graded using a clinical activity score (CAS). Results: Surgery was successful in 77 orbits (87.5%). The remaining 11 orbits (12.5%) needed further surgery to treat DON definitively. All parameters of visual function improved significantly at follow-up and GO inactivated (CAS <3) within 1 month. At 3 months, all 77 responding orbits had p-BCVA >0.63 whereas all of the 11 non-responding orbits had p-BCVA ≤0.63. Visual field parameters and color sensitivity were not associated with response to surgery. High-dose steroid treatment before surgery was associated with a better response rate (96% vs. 73%; p = 0.004). Balanced decompression was associated with a higher response rate compared with medial wall decompression (96% vs. 80%; p = 0.04). A significant inverse correlation was observed between final p-BCVA and the patient's age (r = -0.42; p = 0.0003). Conclusions: Surgical decompression was found to be a very effective treatment for DON. In this study, all clinical parameters improved after surgery and further intervention was rarely needed.

Ischemic optic neuropathy as first presentation in patient with m.3243 A > G MELAS classic mutation.

BACKGROUND: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a systemic disorder in which multi-organ dysfunction may occur from mitochondrial metabolism failure. Maternally inherited mutations in the MT-TL1 gene are the most frequent causes for this disorder. Clinical manifestations may include stroke-like episodes, epilepsy, dementia, headache and myopathy. Among these, acute visual failure, usually in association with cortical blindness, can occur because of stroke-like episodes affecting the occipital cortex or the visual pathways. Vision loss due to optic neuropathy is otherwise considered a typical manifestation of other mitochondrial diseases such as Leber hereditary optic neuropathy (LHON). CASE PRESENTATION: Here we describe a 55-year-old woman, sister of a previously described patient with MELAS harbouring the m.3243A > G (p.0, MT-TL1) mutation, with otherwise unremarkable medical history, that presented with subacute, painful visual impairment of one eye, accompanied by proximal muscular pain and headache. Over the next weeks, she developed severe and progressive vision loss limited to one eye. Ocular examination confirmed unilateral swelling of the optic nerve head; fluorescein angiography showed segmental perfusion delay in the optic disc and papillary leakage. Neuroimaging, blood and CSF examination and temporal artery biopsy ruled out neuroinflammatory disorders and giant cell arteritis (GCA). Mitochondrial sequencing analysis confirmed the m.3243A > G transition, and excluded the three most common LHON mutations, as well as the m.3376G > A LHON/MELAS overlap syndrome mutation. Based on the constellation of clinical symptoms and signs presented in our patient, including the muscular involvement, and the results of the investigations, the diagnosis of optic neuropathy as a stroke-like event affecting the optic disc was performed. L-arginine and ubidecarenone therapies were started with the aim to improve stroke-like episode symptoms and prevention. The visual defect remained stable with no further progression or outbreak of new symptoms. CONCLUSIONS: Atypical clinical presentations must be always considered in mitochondrial disorders, even in well-described phenotypes and when mutational load in peripheral tissue is low. Mitotic segregation of mitochondrial DNA (mtDNA) does not allow to know the exact degree of heteroplasmy existent within different tissue, such as retina and optic nerve. Important therapeutic implications arise from a correct diagnosis of atypical presentation of mitochondrial disorders.