Neuro-Ophthalmic Literature Review

Neuro-Ophthalmic Literature Review David A. Bellows, Noel C. Y. Chan, John J. Chen, Hui-Chen Cheng, Peter W. MacIntosh, Michael S. Vaphiades, Konrad P. Weber, and Xiaojun Zhang The Medical Eye Center, Manchester, New Hampshire, USA; Department of Ophthalmology & Visual Sciences, Prince of Wales Hospital & Alice Ho Miu Ling Nethersole Hospital, Hong Kong; Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong; Departments of Ophthalmology and Neurology, Mayo Clinic, Rochester, Minnesota, USA; Department of Ophthalmology, Taipei Veterans General Hospital, Taipei, Taiwan. Department of Ophthalmology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; Department of Ophthalmology, Illinois Ear and Eye Infirmary, Chicago, Illinois, USA; Departments of Ophthalmology, Neurology, and Neurosurgery, UAB Callahan Eye Hospital, Birmingham, AL, USA; Departments of Neurology and Ophthalmology, University Hospital Zurich, Zürich, Switzerland; Department of Neurology, Ohio State University Medical Center, Ohio, USA. Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China Oculomotor Nerve Schwannoma: Case Series and Literature Review Douglas VP, Flores C, Douglas KA, Strominger MB, Kasper E, Torun N. Oculomotor nerve schwannoma: Case series and literature review. Surv Ophthalmol. 2022 Jul–Aug;67(4):1160–1174. There have only been 100 reported cases of oculomotor nerve schwannoma and, due to its rarity, there is no established guideline for the management of these tumours. Based on a review of the literature and their own cases, the authors have developed an algorithm that addresses the indications for treatment and their outcomes Eighty-four cases of oculomotor nerve schwannoma reported between 1980 and 2020 were included in this review. The mean age at diagnosis was 32.7 years (range 2 months to 78 years) with a male-to-female ratio of 2:3. Four of these patients were asymptomatic. The remaining patients reported symptoms of third nerve palsy including diplopia (n = 24) and ptosis (n = 30). Twenty-three of the patients experienced symptoms suggestive of ophthalmoplegic migraine with headache followed by brief periods of diplopia or ptosis. Other symptoms included those related to the mass effect of the tumour including cognitive changes, periorbital pain, and nausea. Patients with larger tumours (mean 27.3 mm) were primarily treated surgically, which frequently resulted in a complete palsy of the third nerve. Patients with smaller tumours did well with stereotactic radiosurgery, which resulted in a reduction in tumour size with no worsening of symptoms. Considering the above findings, the authors proposed the following algorithm. Patients who are asymptomatic can be monitored with no intervention. Patients with smaller tumours, who are symptomatic, can be treated with stereotactic radiosurgery followed by the prescription of spectacles containing a prismatic correction or strabismus surgery. Patients with large tumours and those with complete third nerve palsy, significant displacement of soft tissues, or major symptoms can be treated with surgical resection which, if necessary, can be followed by stereotactic radiosurgery David Bellows Does a Larger Medial Rectus Predict Dysthyroid Optic Neuropathy? Berger M, Matlach J, Pitz S, Berres M, Axmacher F, Kahaly GJ, Brockmann MA, Müller-Eschner M. Imaging of the medial rectus muscle predicts the development of optic neuropathy in thyroid eye disease. Sci Rep. 2022 April 15;12(1):6259. Dysthyroid optic neuropathy (DON) is one of the severe complications of thyroid eye disease (TED). This retrospective study aimed to stratify the risk of DON development via orbit evaluation and extraocular muscle volumetric analysis using computed tomography. CONTACT John J. Chen Chen.john@mayo.edu Department of Ophthalmology, Mayo Clinic, 200 First Street, SW, Rochester, Mn 55905 NEURO-OPHTHALMOLOGY 2022, VOL. 46, NO. 5, 351–358 https://doi.org/10.1080/01658107.2022.2132065 © 2022 Taylor & Francis Group, LLC Among 92 patients with clinically diagnosed TED, 49 patients (98 orbits) were allocated to the TED-only group. DON was diagnosed in 43 patients, of which 76 orbits were allocated to the TED+DON group. Orbits of the unaffected eyes (10 orbits) in patients with unilateral DON were allocated to the TED+DON (unaffected) group. Forty orbits of 20 subjects were recruited as controls. Muscle volumes of each muscle were significantly higher in the TED+ON group than the TED alone group. However, the authors found that medial rectus (MR) muscle volume was the strongest predictor for the development of DON and they suggested patients with a MR muscle volume of >0.9 cm should be monitored more closely. This is most likely due to its close anatomical relationship with the optic nerve in the optic canal. Although the dimensions of the bony orbit significantly differed among the examined groups, there was no difference predisposing to the development of DON in patients with TED. The change in medial orbital wall angle noted in TED+DON patients is likely to be the compensatory mechanism of MR enlargement instead of the culprit in DON development. Nevertheless, the increased bowing of the medial wall may serve as a surrogate parameter for the increase in muscle volume. While most subjects exhibiting DON showed a distinct increase in muscle volume in this study, a subset showed no or barely any increase in the scatter plot data. Despite the correlation, data from muscle volume and orbit evaluation alone were not sufficient in distinguishing DON and non-DON orbits in patients with TED. This confirms the heterogeneity of this disease with several existing subtypes, which require additional imaging modalities to delineate. Functional and morphological parameters of extraocular muscles can be better studied using magnetic resonance imaging or positron emission tomography where inflammation can be highlighted. Before we can rely on radiological examination in stratifying the risk of DON development in patients with TED, regular neuroophthalmological surveillance and visual field examinations are still mandatory. Noel Chan Bell’s Reflex & Wall Decompression Eshraghi B, Moayeri M, Pourazizi M, Rajabi MT, Rafizadeh M. Decreased Bell’s phenomenon after inferior and medial orbital wall decompression in thyroid-associated ophthalmopathy: A double-edged sword in management of the patients. Graefes Arch Clin Exp Ophthalmol. 2022 May;260(5):1701–1705. The inferior rectus (IR) muscle is the major orbital muscle that can influence Bell’s phenomenon in thyroid associated orbitopathy (TAO). Fibroblastic contracture of the IR with restrictive myopathy may result in a reduced Bell’s reflex in patients with TAO. Together with severe proptosis, exposure keratopathy may lead to visual loss in this group of patients. Apart from medical treatment and radiotherapy, orbital wall decompression is sometimes required for patients with moderate-to-severe TAO. This was a prospective study evaluating the change in Bell’s phenomenon after inferior and medial orbital wall decompression in 30 patients with TAO. Results were compared at baseline prior to surgery and six months postoperatively. The authors found that the distance of Bell’s phenomenon significantly decreased after surgery by an average of 3.25 ± 1.57 mm (p < .001). The adjusted Bell’s phenomenon was also noted to have worsened by 1.58 ± 2.13 mm (p < .001). Despite a significant reduction in exophthalmos after the surgery (24.3 ± 3.06 mm to 22.3 ± 2.27 mm, p < .001), the mean corneal stain score was not statistically different after the decompression. The worsening of Bell’s phenomenon after inferior and medial wall orbital wall decompression was hypothesised to be due to the prolapse of the IR and surrounding soft tissue into the opened sinus, which results in the motility disturbance. This is supported by the finding of an increase in elevation deficit noted in this study postoperatively. Future studies evaluating the change in Bell’s phenomenon following medial wall alone or lateral wall decompression without intervention on the inferior wall is required to confirm this hypothesis. Regardless, it is important for clinicians to warn patients of this potential complication after inferomedial orbital wall decompression and to look for similar sequelae in patients presenting with blow-out fracture. Noel Chan 352 ABSTRACT