Abducens Research Articles

Abducens Nerve Palsy Caused by Cavernous Sinus Meningioma Mimicking Tolosa-Hunt Syndrome

Purpose: To report a case of abducens nerve palsy caused by cavernous sinus meningioma mimicking Tolosa-Hunt syndrome (THS).Case summary: A 59-year-female visited to the ophthalmic department for sudden onset of horizontal diplopia for 20 days. The extraocular examination showed 10 prism diopters (PD) esotropia at distant fixation and ortho at near fixation without definitive abduction limitation. At 2 months of follow-up, she showed the 25 PD left esotropia with abduction limitation of the left eye. The ocular pain and headache were newly developed. Magnetic resonance imaging (MRI) with contrast was performed and revealed the enlargement and enhancement of left cavernous sinus. THS was suspected and high dose steroid treatment was performed. The ocular findings and headache were improved after treatment. These symptoms showed waxing and waning with steroid tapering during follow-up. The follow-up MRI showed no definitive improvement of cavernous sinus lesion compared with previous study. The cavernous sinus meningioma was considered. There was no improvement of ocular motility findings during follow-up and the strabismus surgery was performed.Conclusions: The abducens nerve palsy with headache can occur caused by cavernous sinus meningioma. It may be difficult to differentiate it from THS in certain cases.

Botulinum Toxin Injection for the Treatment of Third, Fourth, and Sixth Nerve Palsy: A Meta-Analysis.

The efficacy of botulinum toxin injection for the treatment of third, fourth, and sixth nerve palsy was evaluated. PubMed, Scopus, EMBASE, Web of Science, and Google Scholar databases were searched. Data about the duration of palsy (acute vs chronic), cause of the palsy, type of toxin used, mean dose, and other background characteristics were collected. Outcome variables were success rate (defined by alleviation of diplopia or reduction in eye deviation) and standardized mean difference of prism diopter and abduction deficit before and after injection. The Joanna Briggs Institute checklist was implemented for the risk of bias assessment. The analysis included 38 articles, comprising 643 patients. The overall treatment success rate in acute and chronic nerve palsy was 79% and 33%, respectively. The success rate was not significantly different between different subgroups of age, type of botulinum toxin, pre-injection prism diopter, etiology of the palsy, duration of follow-up, and mean dose of botulinum toxin injection. However, in both acute and chronic palsy, diabetes etiology was accompanied by the highest success rate. Overall symptomatic response to botulinum injection was 84% (95% CI: 67% to 96%), whereas functional response was observed in 64% (95% CI: 47% to 79%) of the patients. The odds ratio for the success rate of treatment of palsies with botulinum toxin versus expectant management was 2.67 (95% CI: 1.12 to 6.36) for acute palsy and 0.87 (95% CI: 0.17 to 4.42) for chronic palsy. Botulinum toxin can be used for the treatment of acute third, fourth, and sixth nerve palsy, especially in patients with acute palsy and more severe tropia. [J Pediatr Ophthalmol Strabismus. 2024;61(3):160-171.].

Case Report: Tolosa-Hunt syndrome, a neuroinflammatory origin of painful ophthalmoplegia

Background Tolosa-Hunt syndrome is a rare neuroinflammatory disease that affects the cavernous sinus and superior orbital fissure, resulting in symptoms of neuropathy. Case presentation We report a case of a 35-year-old male patient with no past medical history who presented to the emergency department (ED) complaining of a four-day history of progressively increasing headaches associated with right eye pain and double vision. A physical examination showed findings suggestive of abducens nerve palsy. A computed tomography (CT) scan showed subtle asymmetric thickening of the right cavernous sinus, which prompted further investigation by magnetic resonance imaging (MRI) scan. The MRI scan showed intensely enhanced soft tissue thickening in the right cavernous sinus region, slightly extending to the right orbital apex, which caused enlargement of the cavernous sinus and appeared isointense to the adjacent muscles on T1 and T2. The diagnosis of Tolosa-Hunt syndrome was made after the exclusion of all other possible pathologies. The patient received prednisolone therapy; his symptoms improved, and he was discharged after three days. Two weeks later, the patient presented again to the ED with the same symptoms and was treated symptomatically. Conclusions This case highlights a very rare etiology for painful ophthalmoplegia, which is Tolosa-Hunt syndrome. Thickening of the cavernous sinus on MRI images with a background history of painful ophthalmoplegia and headache should raise clinician’s suspicion towards the disease. In addition, exclusion of other possible causes is very important, as Tolosa-Hunt syndrome is a diagnosis of exclusion.

Abducens Nerve Palsy Due to Coronavirus Disease (COVID-19)

The main causes of N.VI paralysis in adults are microvascular disease, vasculopathy, tumors, and inflammatory conditions. However, recent studies suggest that neurotropic viruses may be the etiology of N.VI paralysis. COVID-19 also has neurotropic and neuroinvasive capabilities that make the eye susceptible to bilateral optic neuritis, papilledema, and cranial nerve paralysis, the most common of which is abducens nerve palsy. The aim of this literature review is to review studies that describe the occurrence of abducens nerve palsy in COVID-19 patients. The literature search began in the period April-May 2022 from the Google Scholar database (https://scholar.google.com/). This mini review used the AMSTAR (Assessment of Multiple Systemic Review 2, including randomized and nonrandomized studies) checklist and reviewers independently agreed on the selection of eligible studies and reached consensus regarding which studies to include with inclusion criteria. This mini review found that 75% of cases were strongly associated with viral infection and 25% of cases were strongly associated with COVID-19 vaccination. Only 50% of cases report improvement in abducens nerve palsy. This has the implication that with the increasing prevalence of COVID-19 worldwide, ophthalmologists should be aware that abducens nerve palsy may be part of COVID-19.

10249-PEDT-8 CURRENT STATUS AND ISSUES OF PEDIATRIC DIFFUSE INTRINSIC PONTINE GLIOMA (DIPG)

Abstract that predominantly occurs in childhood, with a median survival of less than one year. Herein we present a recent case of DIPG and discuss the current status and future challenges. The patient was a 7-year-old boy who complained of tinnitus, headaches, and unstable gait. The MRI showed diffuse enlargement of the pons, and the contrast-enhanced T1-weighted image exhibited an irregular ring-like enhancement. Neurologically, he presented with left abducens nerve palsy, horizontal gaze nystagmus, significant left ataxia, and truncal ataxia. As the lesion extended to the left cerebellar peduncle, a stereotactic biopsy was performed. However, postoperative bleeding occurred, resulting in transient consciousness disturbance, left facial palsy, speech disturbance, and dysphagia, necessitating enteral nutrition management. The pathological diagnosis was high-grade glioma, IDH wild type, H3K27M mutation (-), TERTp wild type, BRAF V600E mutation (-), BRAF fusion (-), and MGMT unmethylated. After surgery, the patient received radiation therapy (54Gy/30fr), and his symptoms improved, allowing him to resume oral intake. Post-irradiation, the lesion shrank, and he was discharged home without assistance. However, six months later, his symptoms worsened, and he started taking temozolomide orally, but the effect was limited. Nine months later, he became unable to take oral medication, and a central venous port was placed. We coordinated with home care physicians to provide intravenous and palliative treatments, but respiratory and consciousness disturbances gradually worsened, and he died 10 months after the initial diagnosis. The median survival of DIPG patients treated at our hospital is currently 10.5 months, and this case followed a typical course. The development of novel treatments is desired, but due to the rarity of the disease, conducting comparative trials is challenging. Hence, registry data forming a control group are necessary. Additionally, transitioning to home-based palliative care and sharing information on supportive therapies are also critical tasks.

Bilateral abducens nerve palsy from post-spinal-anesthesia-induced bilateral chronic subdural hematoma: case report

BackgroundA chronic cranial subdural hematoma arising after post-spinal anesthesia is a rare but serious and life-threatening complication of spinal anesthesia. It usually mimics the typical post-spinal-anesthesia headache or post-dural-puncture headache, potentially masking its detection. Abducens nerve palsy tends to occur in chronic subdural hematoma of post-dural-puncture etiology rather than in cases attributed to other causes of subdural hematoma. Preferential damage to the abducens nerve is frequent and can be attributed to its anatomic course because the abducens nerve runs in the direction of the typical caudad displacement of the brain related to intracranial hypotension.ObservationHere, we present a report on the clinical presentation, pathogenesis, and management of two cases that developed bilateral abducens nerve palsy following post-spinal anesthesia administered for cesarean sections due to obstetric indications.LessonPost-spinal-anesthesia-induced chronic subdural hematoma, although a rare, life-threatening complication, must be differentiated from post-spinal-anesthesia headache and treated surgically. Cranial nerve palsy (more commonly called abducens nerve palsy) is more common in post-spinal-anesthesia-induced subdural hematoma than subdural hematomas of other etiologies as the cerebrospinal fluid brain cushioning is partly lost. Cranial nerve palsies resolve in most cases if surgery is performed in a timely manner.

Electromyographic predictors of abducens nerve palsy after endoscopic skull base surgery.

Recovery of abducens nerve palsy (ANP) after endoscopic endonasal skull base surgery (ESBS) has been shown to be potentially predicted by postoperative ophthalmological examination. Triggered electromyography (t-EMG) and free-run electromyography (f-EMG) activity provide an intraoperative assessment of abducens nerve function, but associations with long-term ANP outcomes have not been explored. The objective of this study was to describe intraoperative abducens EMG characteristics and determine whether these electrophysiological profiles are associated with immediately postoperative and long-term ANP outcomes after ESBS. The authors conducted a 5-year (2011-2016) retrospective case-control study of patients who underwent ESBS in whom the abducens nerve was stimulated (t-EMG). Electrophysiological metrics were compared between patients with a new postoperative ANP (cases) and those without ANP (controls). Pathologies included chordoma, pituitary adenoma, meningioma, cholesterol granuloma, and chondrosarcoma. Electrophysiological data included the presence of abnormal f-EMG activity, t-EMG stimulation voltage, stimulation threshold, evoked compound muscle action potential (CMAP) amplitude, onset latency, peak latency, and CMAP duration at various stages of the dissection. Controls were selected such that pathologies were similarly distributed between cases and controls. Fifty-six patients were included, 26 with new postoperative ANP and 30 controls without ANP. Abnormal f-EMG activity (28.0% vs 3.3%, p = 0.02) and lack of response to stimulation (27% vs 0%, p = 0.006) were more frequent in patients with immediately postoperative ANP than in controls. Patients with immediately postoperative ANP also had a lower median CMAP amplitude (35.0 vs 71.2 μV, p = 0.02) and longer onset latency (5.2 vs 2.8 msec, p = 0.04). Comparing patients with transient versus persistent ANP on follow-up, those with persistent ANP tended to have a lower CMAP amplitude (12.8 vs 57 μV, p = 0.07) and higher likelihood of not responding to stimulation at the end of the case (45.5% vs 7.1%, p = 0.06). Abnormal f-EMG was not associated with long-term ANP outcomes. The presence of f-EMG activity, lack of CMAP response to stimulation, decreased CMAP amplitude, and increased CMAP onset latency were associated with immediately postoperative ANP. Long-term ANP outcomes may be associated with t-EMG parameters, including whether the nerve is able to be stimulated once identified and CMAP amplitude. Future prospective studies may be designed to standardize abducens nerve electrophysiological monitoring protocols to further refine operative and prognostic utility.

Tolosa-Hunt syndrome and recurrent painful ophthalmoplegic neuropathy, case reports: what to do and when?

BackgroundTolosa-Hunt syndrome (THS) and recurrent painful ophthalmoplegic neuropathy (RPON) are rare diseases reported within the “Painful lesions of the cranial nerves” section of the International Classification of Headache Disorders-3rd edition (ICHD-3). In case of a first painful attack, differential diagnosis could be challenging and many pitfalls are due to the rarity of the disorders and the lack of information about correct medical management in youngsters.Case presentationOur main purpose was to report a new case of THS and a new case of RPON describing management and diagnostic investigation at the time of the first episode.In both cases of THS (13 years old) and RPON (14 years old) a unilateral periorbital headache associated with acute onset of ipsilateral third cranial nerve paresis, scarcely responding to non-steroidal anti-inflammatory drugs (NSAID), was present at the beginning of the first attack. Brain MRI with "time-of-flight" (TOF) angiography and the need to administer steroids (after 72 h from onset) in order to stop pain were the most important handles allowing us to adopt the correct management both in THS or RPON since onset and to face recurrences in RPON by avoiding useless therapy during follow-up.ConclusionUnilateral periorbital headache associated with third-fourth or sixth cranial nerve paresis should ideally be investigated with a full work-up, comprehensive of brain MRI with TOF angiography since the first attack. In cases with negative brain MRI spontaneous resolution should be considered and watchful waiting might be advisable before starting steroid therapy.

Neuro-Ophthalmic Adverse Events of COVID-19 Infection and Vaccines: A Nationwide Cohort Study.

To evaluate the association of COVID-19 infection and vaccination with neuro-ophthalmic adverse events. In this nationwide population-based retrospective cohort study, 8,498,353 patients were classified into three groups: control, COVID-19 infection, and COVID-19 vaccination. We conducted separate analyses for the early phase (within 60 days) and late phases (61-180 days) to estimate the incidence rates and hazard ratio (HR) for each neuro-ophthalmic adverse event. The adverse events included in this analysis were optic neuritis, papilledema, ischemic optic neuropathy, third nerve palsy, fourth nerve palsy, sixth nerve palsy, facial palsy, nystagmus, ptosis, blepharospasm, anomalies of pupillary function, and Guillain-Barré syndrome/Miller Fisher syndrome (GBS/MFS). Neuro-ophthalmic adverse events other than ptosis and GBS/MFS exhibited no significant increase after COVID-19, and their incidence was extremely low. The incidence rate of ptosis in both phases was significantly higher in patients administered COVID-19 vaccination (HR = 1.65 in the early phase and HR = 2.02 in the late phase) than in the control group. Additionally, BNT162b2 conferred a lower ptosis risk than ChAdOx1. GBS/MFS had a significantly higher incidence rate in the early phase (HR = 5.97) in patients with COVID-19 infection than in the control group. Ptosis was associated with COVID-19 vaccination, particularly with the ChAdOx1 vaccine, while GBS/MFS was associated with COVID-19 infection. In contrast, no association was found between other neuro-ophthalmic adverse events and COVID-19 infection or vaccination. These results may provide helpful insights for diagnosing and treating the neuro-ophthalmological adverse events after COVID-19.

SURG-28. MULTI-STAGE, OPEN CRANIAL APPROACHES FOR RESECTION OF PRIMARY INTRACRANIAL NEOPLASMS: A SYSTEMATIC REVIEW OF THE HISTORY AND CURRENT APPLICATIONS

Abstract Staged surgery for skull base lesions has been utilized to facilitate maximal safe resection and optimize outcomes while minimizing morbidity and complications. Conversely, staged surgery for primary intraparenchymal neoplasms is less commonly performed and has not been reported as extensively within the literature. As such, we performed a systematic review to examine the unique surgical indications for staging, timing between stages, specific surgical approaches utilized, and postoperative complications of staged surgery for primary intra-axial neoplasms. METHODS: A literature search was conducted in August 2021 using PubMed, Web of Science, and Cochrane databases using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations. Titles and abstracts were evaluated independently by 2 authors, after which articles were selected for final analysis based on application of strict inclusion criteria during full text screen. Each included article was then qualitatively assessed and relevant variables—including operative approaches, timing, and outcomes—were extracted for synthesis. RESULTS: Of 115 results, 7 articles were included for final analysis and consisted of 17 pediatric and 4 adult patients. Staged approaches were more commonly utilized in the pediatric patient population for resection of astrocytoma and glioma. Pediatric patients had a timing of surgeries ranging from 5–10 days between operations, compared with 18 days to 4 months in adult patients. Complications in pediatric patients were most commonly hemiparesis, hydrocephalus, cranial nerve VI and VII palsies, truncal ataxia, and cerebellar mutism, while complications in adult patients included language and abstract thinking deficits, respiratory failure, and motor weakness. CONCLUSION: This study reports the first comprehensive review of staged surgical procedures for primary, intra-axial cranial neoplasms. There exists a large degree of heterogeneity in complications resulting from staged surgeries for intra-axial neoplasms, which are similar to complications associated with single-stage surgery for intraparenchymal lesions as well as multi-stage surgeries for skull base lesions.

NIMG-77. EARLY DIAGNOSIS OF NEUROCUTANEOUS MELANOSIS MASQUERADING AS SUBARACHNOID HEMORRHAGE

Abstract A 50-year-old male presented to the emergency room with a sudden onset right upper limb facial numbness and dysphasia, soon followed by full-recovery. Brain computed tomography revealed hyperdense lesions within the left frontal sulcus, highly suspicious of subarachnoid hemorrhage. T1-weighted magnetic resonance imaging showed multiple leptomeningeal enhancement in the left frontal area.The digital subtraction angiography indicated an absence of vascular lesions. One-month after, the lesions progressed in the occipital area, when left sixth nerve palsy developed. Multiple giant nevus over the legs, trunk, and scalp had attracted attention. Owing to the suspicious symptomatic leptomeningeal lesions, open biopsy was performed. Surprisingly, diffuse, thick, black-colored tissue infiltration of the subarachnoid space, involving prominent cortical vessels, was noted. Pathology confirmed meningeal melanocytosis. Neurocutaneous melanosis is characterized by giant congenital or multiple satellite nevi and melanocytic tumors of the leptomeninges. Early disease diagnosis is crucial. Once the patient develops neurological symptoms, prognosis could quickly worsen.

Clinical outcomes of stereotactic biopsy on children with pontine diffuse midline glioma.

Diffuse midline glioma (DMG) of the pons occurs in pediatric patients and carries a dismal prognosis. Biopsy is not necessary for diagnosis but provides information, particularly H3K27M status, with prognostic implications. Additionally, biopsy information may open therapeutic options such as clinical trials that require mutation status. Therefore, we sought to assess the safety of surgical biopsy in DMG patients as well as its potential impact on clinical course. Retrospective analysis of patients who were radiographically and clinically diagnosed with pontine DMG in the last 5years was performed. We assessed demographic, clinical, radiographic, surgical, and follow-up data. 25 patients were included; 18 (72%) underwent biopsy while 7 (28%) declined. 12 biopsies (67%) were performed with robotic arm and 5 (27%) with frameless stereotaxy. Three biopsied patients (17%) experienced new post-operative neurologic deficits (1 facial palsy, 1 VI nerve palsy and 1 ataxia) that all resolved at 2-week follow-up. All biopsies yielded diagnostic tissue. Fourteen patients (78%) had H3K27M mutation. Median OS for H3K27M patients was 10months compared to 11months in the wild-type patients (p = 0.30, log-rank test). Median OS for patients enrolled in clinical trials was 12months compared to 8months for non-trial patients (p = 0.076). In our series, stereotactic pontine DMG biopsies did not carry any permanent deficit or complication and yielded diagnostic tissue in all patients. Similar post-operative course was observed in both robot-assisted and frameless stereotactic approaches. There was no significant difference in survival based on mutation status or clinical trial enrollment.

Bilateral Abducens Nerve Palsy and Nystagmus Resolved Upon Intravenous Dextrose Administration in Hypoglycemic Young Female: A Case Report and Review of the Literature

Hypoglycemia can cause a variety of neurological symptoms ranging from mild confusion to seizures and coma. The brain depends heavily on glucose as its main energetic resource, and a decrease in glucose levels can lead to impaired cerebral function. A 38-year-old female presented to the Emergency department with a history of headache, dizziness and asymmetric reactive pupils in addition to bilateral medial strabismus, nystagmus and photophobia. A non-contrast brain Computed Tomography scan was performed showed no significant radiological findings. Laboratory tests were within normal ranges except for a clinically significant hypoglycemia (level II). Intravenous dextrose was administered and strabismus gradually resolved, and headache subsided gradually within an hour. Hypoglycemic state should be investigated first in any patient with sudden neurological deficit.

Preliminary Results of New Modification of Vertical Muscle Transposition to Enhance Abducting Force in Sixth Nerve Palsy

Introduction: Since 1907, multiple transposition procedures have been established for the treatment of abducens paralysis. The purpose of the study was to determine where the transposed muscle should be reattached in order to increase the tangential force necessary to improve abduction. Methods: Retrospective case review of 12 consecutive patients with abducens paralysis who underwent transposition procedures between 2016 and 2019 was conducted. Vertical rectus muscles are transposed to the insertion of lateral rectus muscle; the temporal parts are joined and sutured to the sclera on top of the lateral rectus muscle in the middle of the insertion. The nasal parts are sutured to the sclera following the spiral of Tillaux. The muscle junction suture is placed 8 mm from the insertion, with the temporal parts of the vertical muscles bellies joined and sutured to the lateral rectus muscle. A full-tendon transposition was performed on 11 patients, a half-tendon transposition procedure on 1 patient. The minimum follow-up was 3 months. Results: The mean preoperative deviation was ET of 37° (range: ET 24° to ET 51°). The mean preoperative abduction limitation was 5 mm from midline (range: 7 to 1 mm). The postoperative mean deviation was ET of 2° (range: 0° to ET 5°). The postoperative mean abduction improvement was 5 mm past midline (range: 2–6 mm). There were no complications or signs of anterior segment ischemia. Conclusion: To achieve the maximal abductive force from the transposed muscles, we suggest that the vertical muscles be reattached as close as possible to the middle of the lateral rectus insertion.

Endoscopic Endonasal Approach for Clival Chordomas in Elderly Patients: Clinical Characteristics, Patient Outcome, and Recurrence Rate.

Introduction The endoscopic endonasal route has demonstrated to be the approach of choice for a large majority of clival chordomas (CCs). However, its results in elderly patients are under-evaluated in the literature. The aim of this study is to assess the surgical outcome for these patients, determining the factors associated with a larger tumor resection in this population. Materials and Methods Our institutional database of CC has been retrospectively reviewed, to identify all cases over 65 years old, operated through an endoscopic endonasal approach (EEA). Preoperative clinical and radiological features were considered, as well as surgical results, morbidity, and patients' outcome at follow-up. Results Out of our series of 143 endoscopic surgical procedures for CC, 34 (23.8%) were in patients older than 65 and 10 in older than 75 (7.0%). Gross tumor removal was achieved in 22 cases (64.7%). Complications consisted of 2 (5.9%) postoperative cerebrospinal leaks, 1 (2.9%) meningitis, 1 (2.9%) permanent cranial nerve VI palsy, 1 (2.9%) pneumonia, and 2 (5.9%) urinary infections. In 39.1% of cases, the preoperative ophthalmoplegia improved or resolved. Twenty-seven patients (79.4%) underwent radiation therapy. At follow-up (37.7 ± 44.9 months), 13 patients (38.2%) showed a recurrence/progression and 13 (38.3%) deceased. Conclusion EEA can be a useful approach in elderlies, balancing the large tumor removal with an acceptable morbidity rate, even if higher than that for general CC population. However, patient selection remains crucial. A multidisciplinary evaluation is important to assess not only their medical conditions, but also their social and familiar conditions.

A Case of Abducens Nerve Palsy and Subretinal Fluid Related to Idiopathic Intracranial Hypertension in Androgen Insensitivity Syndrome.

A Case of Abducens Nerve Palsy and Subretinal Fluid Related to Idiopathic Intracranial Hypertension in Androgen Insensitivity Syndrome.

Anteromedial Petrous (Gardner's) Triangle: Surgical Anatomy and Relevance for Endoscopic Endonasal Approach to the Petrous Apex and Petroclival Region.

Triangular corridors have been used as reliable surgical entry points for open transcranial approaches to the petrous apex (PA) and petroclival region (PCR). The endoscopic endonasal approaches have grown rapidly in the last decade, and the indications have advanced. The knowledge of accurate and reliable anatomic landmarks through endoscopic endonasal route is essential and remain to be established. The purpose of this study was to describe the feasibility and surgical exposure of the anteromedial petrous (Gardner's) triangle as a novel corridor to the PA and PCR. Five anatomic specimens were dissected. The PA and PCR were accessed through endoscopic endonasal approaches and contralateral transmaxillary approach. The limits of the anteromedial petrous (Gardner's) triangle were identified and dissected and associated measurements performed. The dissection was divided into 6 steps. The limits of the anteromedial petrous (Gardner's) triangle were identified and defined by the paraclival internal carotid artery anterolaterally, the abducens nerve posteromedially, and the petroclival synchondrosis inferiorly. Three lines were established following the limits of the triangle. The mean distance of the anterolateral limit was 10.03 mm (SD = 0.94), of the posteromedial limit was 20.06 mm (SD = 2.90), and of the inferior limit was 17.99 mm (SD = 2.99). The mean area was 87.56 mm 2 (SD = 20.06). The 3 anatomic landmarks with a critical role to safely define the triangle were the pterygosphenoidal fissure, the petrosal process of the sphenoid bone, and the petroclival synchondrosis. The anteromedial (Gardner's) triangle is a well-defined bone corridor which provides access to the entire petrous bone and petroclival junction through endoscopic endonasal route. Regardless of the anatomic variations or tumor location, the landmarks of the abducens nerve, paraclival internal carotid artery, and petroclival synchondrosis are key for understanding lateral access to tumors extending from the clivus.

Radiological findings in patients with isolated acute-onset ocular motility disorders

ObjectivesTo image or not to image is a critical question in patients with isolated acute-onset ocular motility disorders (AOMD), without any neurological symptoms/signs. Imaging may help in diagnosis; but is associated with risks and costs. The study aimed to evaluate radiological findings in patients with apparently isolated AOMD on clinical exam, and identify patient/disease characteristics more likely to be associated with positive imaging. MethodsA retrospective review of patient charts with isolated AOMD (<3 months onset), who were examined by an ophthalmologist and had imaging at a tertiary-care center over a period of 18 months, was conducted. Ophthalmology exam and diagnostic imaging findings were recorded. Radiological findings were classified as “clinically relevant”, “non-relevant”, and “normal/no positive” findings. Results46 patients were included (3–91 years; 27 males, 19 females). 19 were clinically classified as nerve palsy (1 third, 10 fourth, and 8 sixth nerve), 14 acute-onset esotropia, 3 acute-onset exotropia, 7 acute-onset vertical strabismus inconsistent with nerve palsy, and 3 limitation of elevation/suspected dorsal midbrain syndrome. We found 8/46 (17%) with clinically relevant imaging findings; of these, 5/46 (11%) had positive neuro-imaging findings (mass, malformation, aneurysm, infarct) and 3/46 (7%) had positive orbital imaging findings (thyroid eye disease). Positive neuro-imaging was more common in patients with certain symptoms (headache), in certain clinical diagnostic entities (dorsal midbrain syndrome spectrum, acute-onset esotropia), and in younger patients (<40 years). ConclusionsPositive neuro-imaging findings may be seen even in patients with apparently isolated ocular symptoms/signs on clinical exam. This data may help institutions with decision-making and policy formulation for imaging patients with isolated AOMD.

Two novel CHN1 variants identified in Duane retraction syndrome pedigrees disrupt development of ocular motor nerves in zebrafish.

Duane retraction syndrome (DRS) is a rare congenital eye movement disorder causing by the dysplasia of abducens nerve, and has highly variable phenotype. MRI can reveal the endophenotype of DRS. Most DRS cases are sporadical and isolated, while some are familial or accompanied by other ocular disorders and systemic congenital abnormalities. CHN1 was the most common causative gene for familial DRS. Until now, 13 missense variants of CHN1 have been reported. In this study, we enrolled two unrelated pedigrees with DRS. Detailed clinical examinations, MRI, and the whole exome sequencing (WES) were performed to reveal their clinical and genetic characteristics. Patients from pedigree-1 presented with isolated DRS, and a novel heterozygous variant c.650 A > G, p. His217Arg was identified in CHN1 gene. Patients from pedigree-2 presented with classic DRS and abnormalities in auricle morphology, and the pedigree segregated another novel heterozygous CHN1 variant c.637 T > C, p. Phe213Leu. A variety of bioinformatics software predicted that the two variants had deleterious or disease-causing effects. After injecting of two mutant CHN1 mRNAs into zebrafish embryos, the dysplasia of ocular motor nerves (OMN) was observed. Our present findings expanded the phenotypic and genotypic spectrum of CHN1 related DRS, as well as provided new insights into the role of CHN1 in OMN development. Genetic testing is strongly recommended for patients with a DRS family history or accompanying systemic congenital abnormalities.

Idiopathic Intracranial Hypertension with Disproportionately Enlarged Subarachnoid Space Hydrocephalus on Imaging: A Case Report.

The pathophysiology of idiopathic intracranial hypertension (IIH) and idiopathic normal-pressure hydrocephalus (iNPH) differs in terms of cerebrospinal fluid (CSF) pressure and imaging-related characteristics. A 51-year-old man presented with optic nerve papillary edema, visual disturbance, bilateral abducens nerve palsy, and a wide-based gait. Imaging showed characteristic findings of IIH and disproportionately enlarged subarachnoid space hydrocephalus (DESH)-characteristic of iNPH. A CSF examination revealed marked CSF hypertension. IIH with iNPH-like imaging features (DESH) was diagnosed, and ventriculoperitoneal shunt surgery was performed. Postoperatively, the visual acuity and visual field improved. This report also describes the distinct and overlapping pathophysiological mechanisms of IIH and iNPH.