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.
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 cm3 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 neuro-ophthalmological 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
Is Lower Body Negative Pressure the Answer for Papilloedema During Space Flight?
Pardon LP, Macias BR, Ferguson CR, et al. Changes in optic nerve head and retinal morphology during spaceflight and acute fluid shift reversal. JAMA Ophthalmol. Published online June 16, 2022. doi:10.1001/jamaophthalmol.2022.1946.
Introduction
It has been recently observed that astronauts develop papilloedema, choroidal folds, and hyperopic shift during spaceflight, which is presumably due to the microgravity in space. This has been called spaceflight associated neuro-ocular syndrome (SANS). A proposed potential countermeasure for SANS is lower body negative pressure (LBNP), which was investigated in this study in astronauts during their long-duration International Space Station missions.
Study Design
This was a prospective cohort study of 14 astronauts who underwent optical coherence tomography (OCT) imaging before flight, in-flight, and up to 180 days after return to Earth. In-flight imaging was done during normal weightless conditions and during 10–20 minutes of LBNP exposure.
Outcomes
On flight day 50, four out of the 14 astronauts (29%) had observable optic disc oedema on OCT as measured by an increase in peripapillary total retinal thickness. By flight day 150, nine out of 13 astronauts (69%) had observable optic disc oedema on OCT, but only one astronaut had visible Frisén grade 1 optic disc oedema. Overall, there was a significant increase in minimum rim width, decrease in cup volume, posterior displacement of Bruch membrane opening, and decrease in macular thickness, which returned back to baseline 180 days after returning to Earth. The use of 25 mmHg LBNP for 10–20 minutes did not change these ocular parameters.
Limitations
One of the limitations is the relatively small number of participants. In addition, OCT scans with and without LBNP were not done on the exact same day because of crew-scheduling constraints.
Clinical significance
This study confirms that mild optic disc oedema occurs in the majority of astronauts during spaceflight, but the pathophysiology is different from raised intracranial pressure because there was posterior displacement of Bruch membrane opening and a decrease in macular thickness, which is not expected with raised intracranial pressure. The study also showed that short duration LBNP did not mitigate the ocular changes, suggesting that longer duration treatment may be required and/or other factors are involved. Understanding the ocular changes that occur during spaceflight and ways of mitigating this are important if we are to send astronauts on longer duration spaceflights.
John Chen
The Pattern of Optic Atrophy Differs Between Patients with Wolfram’s Syndrome and Mitochondrial Optic Neuropathies
Barboni P, Amore G, Cascavilla ML, Battista M, Frontino G, Romagnoli M, Caporali L, Baldoli C, Gramegna LL, Sessagesimi E, Bonfanti R, Romagnoli A, Scotti R, Brambati M, Carbonelli M, Starace V, Fiorini C, Panebianco R, Parisi V, Tonon C, Bandello F, Carelli V, La Morgia C. The pattern of retinal ganglion cell loss in Wolfram syndrome is distinct from mitochondrial optic neuropathies. Am J Ophthalmol. 2022 April 19; Article in press.
The authors enrolled 25 patients with Wolfram’s syndrome (WS) and 33 age-matched patients with the mitochondrial optic neuropathy OPA1-related dominant optic atrophy (DOA) to investigate the phenotype differences between these two diseases. In this cohort all of the WS patients had optic atrophy. WS patients had worse visual acuity, visual field mean deviation, and retinal nerve fibre layer (RNFL) loss on optical coherence tomography (OCT), compared with DOA patients. In addition, the above parameters deteriorated faster in WS patients since early age. Conversely, ganglion cell layer (GCL) thickness was overall thinner in DOA patients since early age compared with WS patients. In WS patients, GCL thickness start to drop later in life. Brain magnetic resonance imaging showed bilateral thinning of the anterior optic pathway, especially the prechiasmatic optic nerves and optic tracts in WS patients, which was correlated with the GCL thickness. The authors concluded that WS patients showed a generally more severe and diffuse degeneration of the anterior visual pathways, with fast deterioration of visual parameters since early age, which was different from the more stable visual function but early loss of the retinal ganglion cell bodies in DOA patients.
Hui-Chen Cheng
Biallelic WFS1 Variants Cause More Variable, but More Severe Retinal Ganglion Cell Loss
Majander A, Jurkute N, Burte F, Brock K, Joao C, Huang H, Neveu MM, Chan CM, Duncan HJ, Kelly S, Burkitt-Wright E, Khoyratty F, Lai YT, Subash M, Chinnery PF, Bitner-Glindzicz M, Arno G, Webster AR, Moore AT, Michaelides M, Stockman A, Robson AG, Yu-Wai-Man P. WFS1-Associated optic neuropathy: genotype–phenotype correlations and disease progression. Am J Ophthalmol. 2022 April 22;241:9–27.
The authors enrolled 37 patients with WFS1-associated optic neuropathy (WON) to investigate the pattern of vision loss and genotype–phenotype correlations. They identified 22 recessive and five dominant WFS1 variants. WON patients had significant loss of the peripapillary retinal nerve fibre layer and ganglion cell layer-inner plexiform cell layer complex on optical coherence tomography. In 12 WON patients, who received visual electrophysiological testing, only two patients had normal pattern visual evoked potentials, while the rest had either delayed or undetectable responses. Advanced psychophysical testing indicated involvement of the major retinal ganglion cell (RGC) subpopulations. In addition, WON patients showed an accelerated rate of visual deterioration with increasing age. The dominant variants tended to cause less severe vision loss compared with the recessive WFS1 variants. The phenotype of recessive WFS1 variants ranged from isolated WON to severe multisystem disease, depending on the WFS1 alleles. The authors concluded that WFS1 variants result in heterogenous phenotypes influenced by the mode of inheritance and the disease-causing alleles, with biallelic WFS1 variants cause more variable, but generally more severe vision and RGC loss.
Hui-Chen Cheng
Intracranial Pressure Directly Predicts Headache Morbidity in Idiopathic Intracranial Hypertension
Mollan SP, Wakerley BR, Alimajstorovic Z, Mitchell J, Ottridge R, Yiangou A, Thaller M, Gupta A, Grech O, Lavery G, Brock K, Sinclair AJ. Intracranial pressure directly predicts headache morbidity in idiopathic intracranial hypertension. J Headache Pain. 2021;22:118.
The authors evaluated headache characteristics in patients recruited to the multi-centre randomised controlled intracranial hypertension (IIH) weight trial. All patients had IIH with papilloedema and lumbar puncture opening pressure 25 cm of cerebrospinal fluid.
Sixty-six women (100% of participants) with active IIH were included. The mean age was 32 years and mean body mass index was 43.9 kg/m2. At the time of headache diagnosis 98% of participants reported headache, with 67% having a headache meeting criteria for IIH. Of these headaches, 90% were migraine-like, 40% had migraine aura, 70% had chronic migraine headache, 30% had episodic migraine-like headaches and 35% had medication-overuse headaches. Additional symptoms reported included 81% with photophobia, 60% with phonophobia, and 70% with nausea. Pulsatile tinnitus was found in 74%. Headache was exacerbated by lying flat in 32%, bending in 31% and on Valsalva manoeuvre in 23%.
At baseline, 38% were received medication for lowering intracranial pressure (ICP), including 29% on acetazolamide, 9% on topiramate and 5% on diuretics.
The authors showed a positive relationship between ICP and headache severity and monthly headache days. Patients with the greatest reduction in ICP over 12 months saw the greatest reduction in headache frequency and severity. Patients felt this chronic daily headache was very disabling. Prior to IIH diagnosis, 68% of participants had a diagnosis of migraine, which is much higher than the general population, where it is closer to 29%.
The authors concluded that headache management is an unmet need in IIH without a randomised controlled trial to guide treatment options. The majority of IIH patients have migraine-like headaches, moderate in severity and with a mean frequency of 22 days per month. ICP is related to headache severity and burden. Improving ICP improves headache and patient quality of life. About 1/3 of the patients have medication overuse headaches, further underscoring the need for better patient headache management and education.
Peter MacIntosh
Neuro-ophthalmological Complications of the COVID-19 Vaccines: A Systematic Review
Lotan I, Lydston M, Levy M. Neuro-Ophthalmological complications of the COVID-19 vaccines: A systematic review. J Neuroophthalmol. 2022;42(2):154–162.
The authors performed electronic searches for published literature and a total of 14 case reports and two case series were selected for inclusion, reporting 76 cases of post-COVID-vaccination ophthalmological adverse events. The most common adverse event was optic neuritis (n = 61), followed by uveitis (n = 3), herpes zoster ophthalmicus (n = 2), acute macular neuroretinopathy (n = 2), optic disc oedema as an atypical presentation of Guillain-Barré syndrome (n = 1), arteritic anterior ischaemic optic neuropathy (n = 1), abducens nerve palsy (n = 1), oculomotor nerve palsy (n = 1), Tolosa-Hunt syndrome (n = 1), central serous retinopathy (n = 1), acute zonal occult outer retinopathy (n = 1), and bilateral choroiditis (n = 1). Most cases were treated with high-dose steroids and had a favourable clinical outcome. The authors concluded that considering the number of individuals that have been exposed to the vaccines, the risk seems very low, and the clinical outcome in most cases is favourable. Therefore, on a population level, the benefits of the vaccines far outweigh the risk of neuro-ophthalmological complications.
Michael Vaphiades
Does Tocilizumab Influence Ophthalmic Outcomes in Giant Cell Arteritis?
Bouffard MA, Prasad S, Unizony S, Costello F. Does Tocilizumab influence ophthalmic outcomes in giant cell arteritis? J Neuroophthalmol. 2022 June 1;42(2):173–179.
The authors performed electronic searches of populations similar to those encountered in neuro-ophthalmological practice and found that tocilizumab appears to be effective in decreasing the frequency of giant cell arteritis (GCA) relapse, the proportion of flares involving visual manifestations of GCA, and the likelihood of permanent vision loss. Data regarding the utility of tocilizumab to curtail vision loss at the time of diagnosis were limited to case reports. The authors concluded that compared with conventional corticosteroid monotherapy, treatment of GCA with both corticosteroids and tocilizumab may decrease the likelihood of permanent vision loss.
Michael Vaphiades
Idiopathic Intracranial Hypertension: Incidental Discovery Versus Symptomatic Presentation
Vosoughi AR, Margolin EA, Micieli JA
Idiopathic intracranial hypertension: Incidental discovery versus symptomatic presentation. J Neuroophthalmol. 2022 June 1;42(2):187–191.
The authors retrospectively reviewed 186 consecutive idiopathic intracranial hypertension (IIH) patients evaluated at tertiary neuro-ophthalmology clinics, of which 75 were incidentally discovered and 111 presented due to symptoms of IIH. There were no differences in the proportion of females, age, body mass index, and magnetic resonance imaging findings of empty or partially empty sella. The incidentally discovered group were less likely to have headache, transient visual obscurations, and diplopia at presentation. There was no difference in the proportion of patients who lost weight between the two groups and at baseline. The incidentally detected IIH group had better visual acuity, Humphrey mean deviation and retinal nerve fibre layer thickness. They continued to have better visual acuity and Humphrey mean deviation at final follow-up and only a minority of these patients required treatment. The authors concluded that the way in which patients enter the medical system may be a valuable way to risk stratify IIH patients.
Michael Vaphiades
Use of Retinal Angiography and Magnetic Resonance Imaging in the Diagnosis of Giant Cell Arteritis with Early Ophthalmic Manifestations
Dentel A, Clavel G, Savatovsky J, Vignal C, Senè T, Charbonneau F, Zuber K, Lecler A, Hage R. Use of retinal angiography and MRI in the diagnosis of giant cell arteritis with early ophthalmic manifestations. J Neuroophthalmol. 2022;42(2):218–225.
Retinal angiography (RA) and magnetic resonance imaging (MRI) allow for effective diagnosis of giant cell arteritis (GCA). The authors performed a retrospective study based on the data collected from patients suspected to have GCA on ophthalmological examination. Fluorescein (FA) and indocyanine green (ICG) RAs and MRI were performed and compared with the final diagnosis. Among the 41 patients included, 25 were diagnosed with GCA. Sensitivities and specificities of FA-RA and ICG-RA were similar. MRI, however showed a higher sensitivity and specificity. The authors concluded that RA can be supplemented by MRI to provide the most accurate diagnosis in GCA presenting with visual signs.
Michael Vaphiades
Invasive Fungal Sinusitis in Patients with Coronavirus Disease 2019 Seen in South India
Hema VK, Kumar K, Shah VM. Invasive fungal sinusitis in patients with coronavirus disease 2019 seen in South India. J Neuroophthalmol. 2022;42(2):226–229.
Utilising electronic medical records data, the authors performed a retrospective case series of 10 patients with COVID-19 disease who presented with cranial nerve palsies. Most of the patients (seven out of 10) presented with multiple cranial nerve palsies (MCNP) with poor visual acuity. Two out of the 10 cases succumbed to death due to the intracranial involvement. All MCNP cases had uncontrolled diabetes mellitus with a history of systemic steroids, and neuroimaging of these cases showed sinusitis of varying severity, most of which were suggestive of fungal invasive type. This study emphasises the need to screen for fungal involvement in COVID-19 cases presenting with MCNP, especially in diabetic patients on systemic steroids so that an early diagnosis may reduce visual loss and mortality.
Michael Vaphiades
The Clinical Significance of Small Vessel Vasculitis on Temporal Artery Biopsies
Quigley J, Sammel AM, Laurent R, Brewer J, Hsiao E, Schembri G, Fraser CL. The clinical significance of small vessel vasculitis on temporal artery biopsies. J Neuroophthalmol. 2022;42(2):212–217.
The authors performed a post hoc analysis of patients with suspected giant cell arteritis (GCA) who underwent temporal artery biopsy (TAB) and fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan as part of a prospective GCA and PET cohort. Patients were divided into three groups based on TAB result: positive (inflammation in the main artery wall); negative (no inflammation); and small vessel vasculitis (SVV) with isolated vasa vasorum or periadventitial involvement. Clinical, serological, and PET/CT data of patients with SVV were compared in those with positive and in those with negative biopsies. Out of 58 patients, 11 had SVV, 12 had positive, and 35 had negative biopsies. Patients with SVV had similar clinical, serological, and PET/CT findings to those with negative biopsies. Compared with those with positive biopsies, patients with SVV had lower erythrocyte sedimentation rates (25 versus 78 mm/hour), platelet counts (296 versus 385 × 109/L), and a lower median total vascular score on PET/CT scan (1.0 versus 13.5). The median prednisone dose was lower (4.8 versus 11.7 mg) and fewer were on steroid-sparing agents (20% versus 67%) at 6 months. The percentage of patients with a clinical diagnosis of GCA was similar between those with SVV (3/11, 27.3%) and those with negative biopsies (5/35, 14.3%). The authors concluded that patients with SVV on TAB had similar clinical features, PET/CT findings, and 6 month outcomes to those with negative biopsies and that small vessel vasculitis can be considered as equivalent to a negative biopsy when being considered for diagnosis and treatment of GCA.
Michael Vaphiades
Diagnosing and Quantifying a Common Deficit in Multiple Sclerosis: Internuclear Ophthalmoplegia
Nij Bijvank JA, van Rijn LJ, Baulk LJ, Tan HS, Uitdehaag BMJ, Petzold A. Diagnosing and quantifying a common deficit in multiple sclerosis: Internuclear ophthalmoplegia. Neurology. 2019 May 14;92(20):e2299-e2308.
Internuclear ophthalmoplegia (INO) is one of the few MS symptoms where the culprit lesion can be precisely located in the medial longitudinal fasciculus (MLF) of the brainstem. However, the clinical diagnosis of INO can easily be missed by the naked eye. With the advent of video oculography (VOG) it is possible to measure the versional disconjugacy index (VDI) to quantify INO. In their paper, the authors compared 210 MS patients with 58 healthy controls. Based on a composite VDI score from 15° saccades they found an INO in 34% of the patients, which was bilateral in more than one-third. Thirty-five percent of MS patients also reported double vision, which was corroborated by a lower vision-related quality of life in MS patients with INO. Based on their results, the authors propose INO measures with VOG as a promising parameter for clinical MS trials.
Konrad P. Weber
Law of Supply and Demand, What is the Price?
Aly L, Noll C, Wicklein R, Wolf E, Romahn EF, Wauschkuhn J, Hosari S, Mardin C, Berthele A, Hemmer B, Korn T, Knier B. Dynamics of retinal vessel loss after acute optic neuritis in patients with relapsing multiple sclerosis. Neurol Neuroimmunol Neuroinflamm. 2022 March 17;9(3):e1159. doi: 10.1212/NXI.0000000000001159. PMID: 35301260; PMCID: PMC8931743.
Background and Objectives
Rarefication of the retinal vasculature as measured by optical coherence tomography (OCT) angiography (OCT-A) is a novel finding in patients with multiple sclerosis (MS). This study aimed to analyse longitudinal dynamics of the retinal vasculature following an acute inflammatory relapse including acute optic neuritis (ON) and to search for associations with alterations of the retinal architecture and visual function.
Methods
This prospective longitudinal cohort study included patients with relapsing-remitting MS or clinically isolated syndrome having an acute ON (n = 20) or a non-ON relapse (n = 33). Patients underwent examinations at baseline and after 7, 14, 28, 90, and 180 days with OCT, OCT-A, and assessment of the high- (HCVA) and low-contrast visual acuity (LCVA).
Results
Retinal vessel loss of the superficial vascular complex (SVC) evolved early after ON and reached a plateau between 90 and 180 days (relative vessel loss 15% ± 8% [mean ± standard deviation]). In addition, an 18% ± 18% intra-individual increase of the foveal avascular zone (FAZ) was evident within 180 days after acute ON. Both SVC thinning and FAZ enlargement were associated with worse HCVA and LCVA. Rarefication of the SVC evolved simultaneously to thinning of the common ganglion cell and inner plexiform layer (GCIP) after ON. No alterations of the deep vascular complex were seen in eyes with ON, and no alterations of the retinal vasculature were recognised in patients having acute non-ON relapses.
Discussion
Rarefication of the SVC and growing of the FAZ evolve rapidly after ON and are linked to persistent visual disability. ON-related SVC thinning might be closely linked to GCIP atrophy and might occur due to an altered local metabolic activity within inner retinal layers.
Comments
Decreased peripapillary and macular area superficial retinal vessels have been reported in the eyes of MS patients with and without a history of ON. The underlying mechanism, however, is not yet understood. It is a matter of debate whether ON-related retinal vessel loss results primarily from direct local inflammatory processes or whether it is a secondary phenomenon due to metabolic changes and reduced oxygen demand after the decline of ganglion cells and axons. This prospective longitudinal study provided evidence suggestive decreased metabolic demand might be the cause of decreased retinal blood supply.
Xiaojun Zhang
Silent Loss Around the Centre
Aly L, Strauß EM, Feucht N, Weiß I, Berthele A, Mitsdoerffer M, Haass C, Hemmer B, Maier M, Korn T, Knier B. Optical coherence tomography angiography indicates subclinical retinal disease in neuromyelitis optica spectrum disorders. Mult Scler. 2022 Apr;28(4):522–531. doi: 10.1177/13524585211028831. Epub 2021 July 14. PMID: 34259579; PMCID: PMC8961243.
Background
Neuromyelitis optica spectrum disorders (NMOSD) are neuroinflammatory diseases of the central nervous system. Patients suffer from recurring relapses and it is unclear whether relapse-independent disease activity occurs and whether this is of clinical relevance.
Objective
To detect disease-specific alterations of the retinal vasculature that reflect disease activity during NMOSD.
Methods
Cross-sectional analysis of 16 patients with NMOSD, 21 patients with relapsing-remitting multiple sclerosis, and 21 healthy controls using retinal optical coherence tomography (OCT), OCT angiography (OCT-A), measurement of glial fibrillary acidic protein (GFAP) serum levels, and assessment of visual acuity.
Results
Patients with NMOSD but not multiple sclerosis had lower foveal thickness (FT) (p = .02) measures and an increase of the foveal avascular zone (FAZ) (p = .02) compared with healthy controls independent of optic neuritis (ON). Reduced FT (p = .01), enlarged FAZ areas (p = .0001), and vessel loss of the superficial vascular complex (p = .01) were linked to higher serum GFAP levels, and superficial vessel loss was associated with worse visual performance in patients with NMOSD, irrespective of ON.
Conclusion
Subclinical parafoveal retinal vessel loss might occur during NMOSD and might be linked to astrocyte damage and poor visual performance. OCT-A may be a tool to study subclinical disease activity during NMOSD
Comments
Subclinical parafoveal thinning and loss of parafoveal vasculature occur independently of ON in NMOSD are the main findings of this study. The authors discussed that this phenomenon might be directly linked to the pathology of aquaporin 4 (AQP4) antibody-positive NMOSD, since the parafoveal areas of the retina contain the highest density of astrocytic Müller cells, which express AQP4 and have shown to be the targets of AQP4 antibodies in NMOSD. This suggests that subclinical disease activity occurs in NMOSD and might drive relapse-independent disease progression. The limitations of this interesting study includes the small sample and the lack of longitudinal study for further understanding of the mechanism.
Xiaojun Zhang