Neural consequences of symptomatic convergence insufficiency: A small sample study.

INTRODUCTION: Convergence insufficiency (CI) is an oculomotor abnormality characterised by exophoria and inadequate convergence when focusing on nearby objects. CI has been shown to cause symptoms when reading. However, the downstream consequences on brain structure have yet to be investigated. Here, we investigated the neural consequences of symptomatic CI, focusing on the left arcuate fasciculus, a bundle of white matter fibres which supports reading ability and has been associated with reading deficits. METHODS: We compared the arcuate fasciculus microstructure of participants with symptomatic CI versus normal binocular vision (NBV). Six CI participants and seven NBV controls were included in the analysis. All participants were scanned with 3 T magnetic resonance imaging (MRI), and anatomical and diffusion-weighted images were acquired. Diffusion-weighted images were processed with TRACULA to identify the arcuate fasciculus in each participant and compute volume and radial diffusivity (RD). RESULTS: Compared with NBV controls, those with symptomatic CI had significantly smaller arcuate fasciculi bilaterally (left: t = -3.21, p = 0.008; right: t = -3.29, p = 0.007), and lower RD in the left (t = -2.66, p = 0.02), but not the right (t = -0.81, p = 0.44, false discovery rate (FDR)-corrected p > 0.05) arcuate fasciculus. Those with higher levels of reading symptoms had smaller arcuate fasciculi (r = -0.74, p = 0.004) with lower RD (r = -0.61, p = 0.03). CONCLUSIONS: These findings suggest that symptomatic CI may lead to microstructural changes in the arcuate fasciculus. Since it is highly unlikely that abnormalities in the arcuate fasciculus are the cause of the neuromuscular deficits in the eyes, we argue that these changes may be a potential neuroplastic consequence of disruptions in sustained reading.

Pearls & Oy-sters: Ocular Myasthenia Gravis: Central Ocular Motor Signs and Unilateral Visual Loss Caused by the Great Neuro-Ophthalmologic Impersonator.

Myasthenia gravis (MG) has been described as a great mimicker of other neurologic and ocular motility disorders, including centrally mediated ophthalmoplegia. For example, ocular myasthenia gravis (ocular MG) may cause impaired binocular visual acuity for near vision due to reduced accommodation or for distance vision due to accommodative excess. Notably, accommodative excess due to ocular MG is rare, but may occur with exotropia, with or without diplopia. We report 2 cases of ocular MG: First, a 32-year-old man with exotropia, bilateral hypometric and slowed adducting saccades with dissociated abducting nystagmus, miosis, and decreased distance vision in his right eye; second, a 45-year-old man with similar ocular motor deficits, miosis, and myopia. Both patients showed ocular motor deficits which appeared to localize to the pons but were instead due to ocular MG. Ocular MG should be considered in patients who present with reduced visual acuities due to any disruption in accommodation. Any ocular motor deficit, even if appearing to be centrally mediated or occurring without ptosis, may be caused by ocular MG.

An unexpected turn: a case of torsional anomalous retinal correspondence after myectomy of previously anteriorized inferior oblique muscles in a child.

We report a case of torsional diplopia caused by presumed torsional anomalous retinal correspondence after myectomy of previously asymmetrically anteriorized inferior oblique muscles for inferior oblique overaction. Given this patient's experience, it may be prudent to operate with caution on previously anteriorized inferior oblique muscles, especially when anteriorization is performed at a very young age.

Sensitivity of Magnetic Resonance Imaging of the Medial Longitudinal Fasciculus in Internuclear Ophthalmoplegia.

BACKGROUND: Internuclear ophthalmoplegia (INO) is a result of insult to the medial longitudinal fasciculus (MLF). Clinicoradiological correlation in patients with INO has been reported to be poor; however, prior studies have used low resolution MRI imaging techniques and included patients with subclinical INO. We aimed to determine the sensitivity of modern MRI interpreted by a specialist neuroradiologist to detect clinically evident INO. METHODS: A retrospective chart review of patients in 2 tertiary University-affiliated neuro-ophthalmology practices with the diagnosis of INO. MRI scans of all patients were reviewed and interpreted by a fellowship-trained neuroradiologist for the presence of lesion in MLF and concordance with the original imaging report. RESULTS: Forty-five patients were included in the study: 33 with demyelinating disease, 11 with stroke, and 1 with intracranial mass. A visible MLF lesion was present in 25/33 demyelinating cases and 7/11 ischemic cases. Lesions in 2 cases in each group were identified only after review by a fellowship-trained neuroradiologist. In demyelinating INO, patients with a visible MLF lesion were more likely to show other brainstem (72%) and supratentorial (51%) white matter lesions. CONCLUSIONS: In 25% of patients with demyelinating INO and 33% of patients with ischemic INO, no visible lesion was identified on current high-quality MRI imaging. Review of imaging by a neuroradiologist increased the possibility of lesion been identified.

Acute bilateral hypotropia and esotropia complex as first manifestation of multiple sclerosis: a case report.

A 21-year-old Japanese woman presented with sudden eye movement disorders. An ophthalmic examination revealed bilateral hypotropia and esotropia complex. Brain magnetic resonance imaging revealed abnormal signals in the posterior and medial part of the lower pontine tegmentum (including periventricular and subcortical white matter) that were suggestive of demyelination. A cerebrospinal fluid test was positive for oligoclonal bands. She was subsequently diagnosed with multiple sclerosis and was administered intravenous methylprednisolone and oral dimethyl fumarate, with complete recovery from hypotropia and esotropia after two months. Bilateral hypotropia and esotropia are important clinical signs for the accurate diagnosis of multiple sclerosis.

Ocular motor disorders in children and adults with mTBI: a scoping review protocol.

INTRODUCTION: Ocular motor function is susceptible to neurological injury because it requires a large portion of brain circuitry including every lobe of the brain, brainstem, thalamus, basal ganglia, cerebellum, cranial nerves and visual tracts. While reports of a high frequency of ocular motor dysfunctions after mild traumatic brain injury (mTBI) span multidisciplinary journals, there is no scoping review of the signs, diagnostic assessments and criteria, and appropriate management of ocular motor disorders post-mTBI. Post-mTBI ocular motor dysfunction has been reported to respond to active treatment. The objective of this scoping review is to map the available evidence on the diagnostic assessment and treatment modalities currently used in the management of mTBI-related ocular motor disorders in children and adults. This scoping review also aims to identify gaps in the current literature and provide suggestions for future research. METHODS AND ANALYSIS: This review will include populations with reported concussion and/or mTBI without restrictions on age, race, sex or time since injury. The review will evaluate the reported symptoms related to ocular motor dysfunction, types of assessments and diagnostic criteria used, reported treatments, and the level of evidence supporting the reported treatments. This review will exclude literature on brain injury of non-traumatic aetiology and moderate/severe traumatic brain injury. Ocular motor dysfunction after mTBI appears in journals across multiple disciplines. Thus, multiple databases will be evaluated including Pubmed, Embase, PEDro, OVID, Clinical Key, Google Scholar and REHABDATA. Literature will be searched from inception to present day. Evidence sources will include experimental study designs including randomised controlled trials, non-randomised controlled trials and interrupted time-series. Additionally, analytical observational studies including prospective and retrospective cohort studies, case series, cross-sectional studies and clinical practice guidelines will be considered for inclusion. Data will be extracted on clinical presentation, frequency, assessment, diagnostic criteria management strategies and outcomes of concussion and mTBI-related ocular motor disorders. ETHICS AND DISSEMINATION: This scoping review will use data from existing publications and does not require ethical approval by an institutional review board. Results will be disseminated through publication in a peer-reviewed scientific journal and presented at relevant conferences and as part of future workshops with professionals involved with diagnosis and management of patients with mTBI.

Opsoclonus and ocular flutter: evaluation and management.

PURPOSE OF REVIEW: Opsoclonus and ocular flutter are saccadic intrusions characterized by spontaneous, back-to-back, fast eye movements (saccades) that oscillate about the midline of central visual fixation without intervening inter-saccadic intervals. When this type of movement occurs exclusively in the horizontal plane, it is called ocular flutter. When it occurs in multiple planes (i.e. horizontal, vertical, and torsional) it is called opsoclonus. The most common etiologic categories are parainfectious and paraneoplastic diseases. Less common are toxic-metabolic, traumatic, or idiopathic origins. The mechanism of these movements relates to dysfunction of brainstem and cerebellar machinery involved in the generation of saccades. In this review, we discuss the characteristics of opsoclonus and ocular flutter, describe approaches to clinical evaluation and management of the patient with opsoclonus and ocular flutter, and review approaches to therapeutic intervention. RECENT FINDINGS: Recent publications demonstrated eye position-dependent opsoclonus present only in left gaze, which may be related to dysfunction of frontal eye fields or structures in the cerebellar vermis. SUMMARY: Opsoclonus and ocular flutter originate from a broad array of neuropathologies and have value from both a neuroanatomic and etiologic perspective.

Contrast sensitivity, optotype acuity and fixation eye movement abnormalities in amblyopia under binocular viewing.

INTRODUCTION: Visual function deficits are seen in amblyopic subjects during fellow and binocular viewing. The purpose of the study was to examine the relationship between Fixation Eye Movement (FEM) abnormalities and binocular contrast sensitivity and optotype acuity deficits in amblyopia. METHODS: We recruited 10 controls and 25 amblyopic subjects [Anisometropic = 6, Strabismic = 10, Mixed = 9]. We measured binocular contrast sensitivity at spatial frequencies 1,2, 4, 8, 12 and 16 and binocular and monocular optotype acuity using a staircase procedure. We recorded FEMs using high-resolution video-oculography and classified subjects as having no nystagmus(None = 9) or nystagmus without FMN(n = 7) and with Fusion Maldevelopment Nystagmus (FMN)(n = 9). We computed the fixation instability, amplitude and velocity of the fast and slow FEMs. RESULTS: Amblyopic subjects with and without nystagmus had worse binocular contrast sensitivity at spatial frequencies 12 and 16 and binocular optotype acuity than controls. The abnormalities were most pronounced in amblyopic subjects with FMN. Fixation instability of the Fellow Eye and Amblyopic Eye and vergence instability, amplitude of fast FEMs and velocity of slow FEMs were increased with reduced binocular contrast sensitivity and reduced optotype acuity in amblyopic subjects. CONCLUSIONS: Fixation instability of Fellow Eye and Amblyopic Eye, optotype acuity and contrast sensitivity deficits are seen under binocular viewing in amblyopic subjects with and without nystagmus but are most pronounced in those with FMN. FEMs abnormalities correlate with both lower order (contrast sensitivity) and higher order (optotype acuity) visual function impairment in amblyopia.

A Treatment Approach in Congenital Fibrosis of Extraocular Muscles.

Background: Congenital fibrosis of extraocular muscles ( CFEOM) is a group of genetically defined eye-moving disorders. The syndrome is clinically characterized by congenital non-progressive ophthalmoplegia caused by dysinervation of the cranial nerves with or without ptosis. As a main sign of a CFEOM, extraocular muscles get shrunken and fibrotic, which makes surgery more technically demanding and the result more unpredictable, which makes the treatment challenging and highly customized. Our paper presents variations of the clinical picture and treatment cases of CFEOM1. Objective: To outline the importance of the clinical examination with the exact measurement of deviations for the patients with ocular fibrosis and passive duction test under general anesthesia, establishing them as the main criteria for treatment. Methods: We treated seven patients (14 eyes) with CFEOM1. The decision of the treatment was based on the measurement of the eye position in the primary position (PP), the severity of compensatory head position (CHP), restriction of motility, and passive motility test performed before surgery in general anesthesia. In 3 cases, patients were treated conservatively with the treatment of refractive error and amblyopia. However, in 4 patients, CHP and position of the eyes in PP were not acceptable, motility was severely impaired, and patients underwent surgery. The first surgery was performed on eye muscles: recession of inferior rectus muscle (IRM), anteposition, and resection of superior rectus muscle (SRM). As a second step procedure, ptosis surgery was performed. When the muscle was too tight, and it wasn't possible to have a satisfying result with conventional surgery, we used a tissue expander to improve the position and motility of the affected eyes. Results: In all operated cases, CHP has significantly improved and the position of the eyes in PP. Conclusion: Exact eye and head position measurements and a passive motility test during general anesthesia should guide the surgery. In the case when conventional surgery is not possible, implantation of a bovine pericard is a safe and effective method.

Multiple system atrophy with oculomotor abnormalities as a prominent manifestation: A case series.

RATIONALE: Multiple system atrophy (MSA) is a group of adult-onset sporadic neurodegenerative diseases, mainly classified as MSA-C and MSA-P types. Due to the diversity of clinical symptoms, diagnosis faces a significant challenge. In the present case, we report a patient with isolated vertigo as the first presentation and abnormalities of the oculomotor system as the characteristic manifestations. CASE CONCERN: A 64-year-old male had dizziness for 1 year, aggravated for 4 months, with accompanying symptoms of unsteady walking. Physical examination revealed spontaneous nystagmus, abnormal ataxic movements, and a broad basal gait. Video nystagmography revealed saccade intrusions and macrosaccadic oscillations, and opsoclonus. Magnetic resonance imaging (MRI) was unremarkable early, and positron emission tomography-computed tomography (PET-CT) announced a reduction in the volume of the cerebellum and brainstem. DIAGNOSIS: The diagnosis of the possibility of MSA type-C, peripheral neuropathy, hypertension, and lacunar cerebral infarction was performed. CONCLUSION: Atypical early clinical presentation may lead to delays, and identifying the critical problem through the patient simple clinical status requires long-term clinical experience and various ancillary examination tools.

Oculomotor abnormalities indicate early executive dysfunction in prodromal X-linked dystonia-parkinsonism (XDP).

BACKGROUND: X-Linked dystonia-parkinsonism (XDP) is a movement disorder characterized by the presence of both dystonia and parkinsonism with one or the other more prominent in the initial stages and later on manifesting with more parkinsonian features towards the latter part of the disease. XDP patients show oculomotor abnormalities indicating prefrontal and striatal impairment. This study investigated oculomotor behavior in non-manifesting mutation carriers (NMC). We hypothesized that oculomotor disorders occur before the appearance of dystonic or parkinsonian signs. This could help to functionally identify brain regions already affected in the prodromal stage of the disease. METHODS: Twenty XDP patients, 13 NMC, and 28 healthy controls (HC) performed different oculomotor tasks typically affected in patients with parkinsonian signs. RESULTS: The error rate for two types of volitional saccades, i.e., anti-saccades and memory-guided saccades, was increased not only in XDP patients but also in NMC compared to HC. However, the increase in error rates of both saccade types were highly correlated in XDP patients only. Hypometria of reflexive saccades was only found in XDP patients. Initial acceleration and maintenance velocity of smooth pursuit eye movements were only impaired in XDP patients. CONCLUSIONS: Despite being asymptomatic, NMC already showed some oculomotor deficits reflecting fronto-striatal impairments, typically found in XDP patients. However, NMC did not show saccade hypometria and impaired smooth pursuit as seen in advanced Parkinson's disease and XDP, suggesting oculomotor state rather than trait signs in these mutation carriers. Neurodegeneration may commence in the striatum and prefrontal cortex, specifically the dorsolateral prefrontal cortex.

Characteristics of binocular vision and oculomotor function among sports-concussed athletes.

Purpose: To compare the binocular vision and oculomotor function between sports-concussed athletes and aged-matched controls. Methods: Thirty mild concussed athletes were recruited and compared with aged-matched controls. All the participants underwent a comprehensive ocular assessment followed by an oculomotor assessment which included tests for accommodation, vergence, eye movements, and reading parameters. Results: Three categories of oculomotor-based deficits were found: convergence insufficiency (40%), accommodative insufficiency (25%), and oculomotor-based reading dysfunctions (20%). A statistically significant reduction in the mean ± SD of the following parameters was noted in concussed athletes v/s controls:- binocular accommodative amplitude: 7.13 ± 1.59 v/s 15.35 ± 2.95 (P < 0.001), convergence amplitude: 14.23 ± 5.00 v/s 5.65 ± 0.90 (P < 0.001), positive fusional vergence for distance: 21.17 ± 8.97 v/s 31.32 ± 6.23 (P < 0.001), vergence facility: 6.47 ± 1.47 v/s 11.84 ± 1.00 (P < 0.001), accommodative facility: 7.10 ± 4.57 v/s 11.67 ± 1.83 (P < 0.001), reading speed: 66.97 ± 17.82 v/s 144.13 ± 24.45 (P = 0.03) and Developmental Eye Movement ratio: 1.40 ± 0.19 v/s 1.17 ± 0.06 (P < 0.001). Conclusion: Concussions caused by sports have a considerable impact on binocular vision and oculomotor parameters. These findings have substantial therapeutic implications in terms of establishing a periodic screening program for athletes so that essential therapy can be provided for a better outcome.

A Case of Parinaud Syndrome in a Patient with Parkinson's Disease: Causal Association or Co-incidental?

Background: Parinaud syndrome is a dorsal mid-brain syndrome characterized by upgaze paralysis, convergence retraction nystagmus, and pupillary light-near dissociation. Infarctions or hemorrhages involving the mid-brain are the most frequent causes in older adults. Objective: To report a novel case of a patient who presented with classical parkinsonian signs and Parinaud syndrome. Material and Methods: Patient data were obtained from medical records from the Department of General Medicine, Burdwan Medical College and Hospital, Burdwan, West Bengal, India. Results: A 62-year-old previously healthy man presented with motor and non-motor symptoms of Parkinson's disease (PD) for the past 6 years. The neurological examination revealed an asymmetric resting tremor of the upper limbs with rigidity, bradykinesia, hypophonia, hypomimia, decreased blinking, and micrographia. The neuro-ophthalmological examination showed Parinaud syndrome. He was treated with levodopa-carbidopa and trihexyphenidyl. After 6 months and 1 year of follow-up, his neurological condition was re-assessed; motor symptoms improved substantially, but Parinaud syndrome persisted. Conclusions: Parinaud syndrome can be a potential manifestation of PD. A detailed neuro-ophthamological examination should be carried out even in patients having a diagnosis of classic PD in whom eye-movement abnormalities are distinctly infrequent.