Ptosis secondary to orbital metastasis undetected by magnetic resonance imaging: A case report.

We report a patient with isolated ptosis secondary to orbital metastasis but no evidence of a neoplastic process on magnetic resonance imaging (MRI). A 69-year-old male was referred to our hospital with ptosis of the right upper eyelid and secondary frontalis muscle overaction on the left side for six months. The palpebral fissure was 3mm on the right and 16mm on the left, and levator function was 6mm and 19mm respectively. Three years previously, he had undergone surgical resection of the left lower lobe of the lung due to a T1 N0 M0 adenocarcinoma, and no recurrence had since been observed. An MRI was performed to rule out ptosis secondary to metastasis. Thyroid dysfunction and myasthenia were also ruled out. The ptosis was attributed to an isolated microvascular third nerve palsy. A standard external levator advancement was performed. Six months after the surgery, the patient presented with intense pain, minimal ptosis, edema and diplopia. A new MRI revealed an orbital metastasis measuring 2.4×1.0×1.6cm in the superior orbit, exerting mass effect on the superior rectus and the levator palpebrae superioris muscle. A positron emission tomography scan revealed a recurrence of the lung cancer with multiple bony metastases. The patient underwent chemotherapy consisting of the taxol-carboplatin protocol. Our report highlights the importance of a high index of suspicion of a neoplastic etiology in patients with mild symptoms and a history of cancer even if imaging does not initially reveal a mass or infiltration.

Postoperative magnetic resonance imaging of the inferior oblique muscle.

No previous imaging study has described the appearance of the inferior oblique muscle after surgery. It is unknown whether findings signifying prior myectomy or recession are recognizable on magnetic resonance (MR) imaging and how they might differ for the two procedures. After myectomy via a temporal approach, the cauterized muscle stump retracts into the medial orbit. How far it retracts and whether it reattaches to the globe remains unclear. To address these issues, orbital MR images were reviewed in 5 patients who had previously undergone inferior oblique myectomy or recession. In each case, the operated muscle exhibited subtle but telltale features, when compared with the normal, fellow inferior oblique. After myectomy, the inferior oblique still terminated lateral to the inferior rectus muscle and appeared closely apposed to the globe, although not necessarily attached to the sclera.

Ophthalmoplegia With Isolated Extraocular Muscle Hypertrophy.

A 60-year-old man is experiencing diplopia but no problems with visual acuity, pain, or other symptoms. A magnetic resonance image of the head shows abnormal thickening and T2 hyperintensity of the right lateral rectus muscle. What is your diagnosis?

Cauterization-mediated restriction from penetrating orbital trauma.

A healthy 32-year-old woman presented with binocular diplopia immediately after sustaining a penetrating injury to the left periocular adnexa with a hot metal skewer. Examination revealed an incomitant esotropia, with complete limitation of abduction of the left eye with downshoot in left gaze and normal afferent visual function. Computed tomography and magnetic resonance imaging demonstrated no fracture, but there was mild thickening of the medial rectus muscle and associated fat stranding. Lack of orbitomuscular tethering or hematoma led to the presumptive diagnosis of thermal cauterization injury causing left medial rectus restriction. Given the lack of literature on this mechanism of injury, the patient was monitored closely. She exhibited remarkable spontaneous improvement in motility over 6 months, with near orthophoria in primary gaze. However, bothersome residual esotropic diplopia in left gaze prompted a left medial rectus recession, with a good outcome. This case demonstrates that isolated extraocular muscle thermal injuries and consequential strabismus can recover spontaneously; longitudinal observation before surgical intervention may be appropriate in such cases.

Magnetic Resonance Imaging of Globe Translation in Abducens Palsy.

PURPOSE: It has been supposed that rectus muscle paralysis would cause proptosis due to the reduction in active posterior tension. This study aimed to test this proposition by evaluating globe translation during horizontal duction in patients with abducens palsy. DESIGN: Prospective, single-center, fellow-eye controlled, case series. METHODS: Horizontal globe rotation and translation were quantified using orbital magnetic resonance imaging of patients with isolated unilateral abducens nerve palsy without other ocular motility disorders. Unaffected fellow eyes served as the control group. Digital image analysis was performed. RESULTS: The study included 5 female and 2 male patients with a mean ± standard deviation age of 52 ± 15 years. The average esotropia was 39.0 ± 9.6 diopters. Mean adduction was similar at 54.9 ± 10.4° in palsied eyes and 52.0 ± 7.1° in fellow eyes. However, abduction in palsied eyes was significantly less at 11.4 ± 7.1° than 37.1 ± 11.4° in fellow eyes (P = .0023). Average anterior translation in adduction was 0.46 ± 0.42 mm in palsied orbits, similar to 0.35 ± 0.47 mm in fellow orbits (P = .90). Anterior translation in abduction averaged 0.17 ± 0.53 mm in palsied orbits, similar to 0.27 ± 0.73 mm in fellow orbits (P = .80). Average medial translation in adduction at 0.32 ± 0.23 mm in palsied orbits was statistically similar to 0.12 ± 0.44 mm in fellow orbits (P = .54). Average lateral translation in abduction at 0.19 ± 0.18 mm in palsied orbits was similar to 0.33 ± 0.15 mm in control orbits (P = .38). CONCLUSION: Abducens palsy does not alter normal eye translation during horizontal duction.

A patient with congenitally restrictive strabismus and contralateral secondary muscle enlargement.

AIM: To report the case of a congenital restrictive strabismus with a contralateral enlargement of extraocular muscles. CASE: The clinical presentation, findings, and postoperative outcomes of a 4 years old boy referred to evaluation for presenting a left eye deviation since birth are detailed. CONCLUSION: A unilateral congenital restrictive strabismus (congenital hypotropia and esotropia) can be the cause of contralateral secondary enlarged extraocular muscle and It must be included in the differential diagnosis.

Magnetic Resonance Imaging Findings in Patients With Duane Retraction Syndrome.

BACKGROUND: Duane retraction syndrome (DRS) is known to relate to the absence of the abducens nucleus, with abnormal innervation of the lateral rectus (LR) muscle by branchesof the oculomotor nerve (CN III). The purposes of this study were to investigate the morphological characteristics of the oculomotor nerve (CN III), the abducens nerve (CN VI), and the extraocular muscles in patients with clinically diagnosed Duane retraction syndrome (DRS) using MRI. In addition, we assessed the association between ocular motility, horizontal rectus muscle volumes, and CN III/VI in patients with Duane retraction syndrome (DRS). METHODS: The study comprised 20 orthotropic control subjects (40 eyes) and 42 patients with Duane syndrome (48 eyes), including 20 patients with DRS Type I (24 eyes), 5 patients with DRS Type II (6 eyes), and 17 patients with DRS Type III (18 eyes). Three-dimensional (3D) T1/2 images of the brainstem and orbit were obtained to visualize the cranial nerves, especially the abducens (VI) and oculomotor (III) nerves, as well as extraocular muscles. RESULTS: Based on the clinical classification, among 42 patients, MRI showed that the abducens nerves (CN VI) on the affected side were absent in 24 of 24 eyes (100%; 20 patients) with Type I DRS and in 16 of 18 eyes (88%; 16 patients) with Type III DRS. However, CN VI was observed in 6 of 6 eyes (100%; 5 patients) with Type II DRS and in 2 of 18 eyes (11%) with Type III DRS. CN III was observed in all patients. The oculomotor nerves on the affected side were thicker than those on the nonaffected contralateral side in DRS Type I ( P < 0.05) and Type III ( P < 0.05), but not in DRS Type II. Smaller LR and larger MR volumes were shown in the affected eye than that in the nonaffected eye in DRS Types I and III. Based on the presence or absence of CN VI, there was a tendency for thicker oculomotor nerves in the affected eye than in the nonaffected eye in the absence groups ( P < 0.05). However, no significant difference was found in the present group. In the CN VI absence groups, similar results were found in the affected eyes than in the nonaffected eyes as in DRS Types I and III. In addition, the presence of CN VI was correlated with better abduction ( P = 0.008). The LR and MR volumes have positive correlations with the oculomotor nerve diameter in the affected eye. However, there was no correlation between the range of adduction/abduction and the LR/MR ratio in patients with or without an abducens nerve. CONCLUSIONS: Different types of DRS have different characteristic appearances of CN VI and CN III on MRI. Horizontal rectus muscles have morphological changes to adapt to dysinnervation of CN VI and aberrant innervation of CN III. Thus, these neuroimaging findings may provide a new diagnostic criterion for the classification of DRS, improving the comprehension of the physiopathogenics of this disease.

Relationship between strabismus associated with Angelman syndrome and orbital anomaly.

PURPOSE: To investigate the relationship between the details of strabismus and orbital abnormalities determined by ocular motility tests and orbital imaging examinations in 9 cases with Angelman syndrome (AS). STUDY DESIGN: A retrospective, clinical report. METHODS: The 9 AS cases (mean age at initial visit: 4.6 ± 8.0 years) were confirmed by genetic diagnosis of the chromosome 15q11-13 region. In all cases, axial imaging of the orbit in the transverse plane of the horizontal extraocular muscles was obtained. The opening angle between both lateral walls of the orbit (greater wing of sphenoid) was measured as the biorbital angle, and compared with the 95% confidence interval of the orbital angle in normal children. RESULTS: All cases had exotropia with means of the distance and near of angle 32.2 prism diopters (Δ) ± 9.7Δ and 32.8Δ ± 8.3Δ. The mean of the biorbital angle was 107.7° ± 7.6°, greater than the biorbital angle of 94.3° ± 5.1° previously reported in 129 normal children (P < 0.0001, t-test). Except for one biorbital angle of 93° in the 25-year-old patient, all the biorbital angles in the 8 children were larger than the upper 95% confidence interval in normal children. Astigmatic and hyperopic ametropic amblyopia were detected in 3 cases and 1 case, respectively. CONCLUSIONS: The frequency of exotropia in AS is higher than previously reported, with our results strongly suggesting that the enlarged biorbital angle is related to the pathogenesis of exotropia in AS.

Effects of various extraocular muscle enlargement patterns on muscle diameter index in graves ophthalmopathy patients: a retrospective cohort study.

Graves ophthalmopathy (GO) patients often undergo retrobulbar injection of glucocorticoids (GCs) as a common therapeutic approach. This study aimed to explore the impact of various patterns of extraocular muscle (EOM) enlargement on EOM changes following retrobulbar GCs injection in patients with GO. A retrospective analysis was conducted on GO patients who underwent retrobulbar GCs injections. Data pertaining to EOM diameter (EMD) and muscle diameter index (MDI) were collected from orbital computed tomography (CT) scans. The MDI change (ΔMDI) was calculated by comparing pre- and post-injection MDI values. The relationship between each pre EMD/MDI and ΔMDI was assessed using univariate and multivariate logistic regression analysis. A total of 68 patients with GO were included in this study, accounting for 118 eyes. After retrobulbar injections of GCs, 84 eyes showed a decrease in the MDI, while 34 eyes exhibited an increase in MDI. A threshold effect was observed in the relationship between medial pre EMD/MDI and ΔMDI. When the medial pre EMD/MDI was less than 0.28, a higher medial pre EMD/MDI was associated with a smaller ΔMDI (ß = - 25.21, p = 0.0175). However, when the medial pre EMD/MDI was greater than 0.28, no significant association was found between pre EMD/MDI and ΔMDI. There was a negative correlation between medial + lateral pre EMD/MDI and ΔMDI (ß = - 11.76, p < 0.0189). A higher medial + lateral pre EMD/MDI was associated with a greater decrease in MDI. Additionally, there was a positive correlation between superior rectus muscle-levator complex (SRLC) pre EMD/MDI and ΔMDI (ß = 11.92, p = 0.040). The higher the value of SRLC pre EMD/MDI, the greater the ΔMDI. There was an association between pre EMD/MDI and changes in EOMs after retrobulbar injection of GCs in GO patients. In patients with predominantly enlarged medial rectus muscles and severe degrees of enlargement, retrobulbar injection of GCs should be assessed for its benefit; a combination of medial and lateral rectus muscle enlargement is beneficial for the shrinkage of EOMs following retrobulbar injections; the involvement of the SRLC rectus muscle may be a disadvantageous pattern of shrinkage of EOMs following retrobulbar injections.Trial registration This study is retrospectively registered. We have registered this study with the Chinese Clinical Trials Registry ( www.chictr.org.cn , registration number: ChiCTR2200063429).

Study 3: Anterior segment optical coherence tomography-guided surgical approach in slipped medial rectus muscle.

Purpose: To discuss the novel swept-source anterior segment optical coherence tomography (SS-ASOCT)-guided surgical approach in slipped medial rectus muscles. Methods: Prospectively (between February 2020 and July 2022), six patients with a clinical suspicion of slipped medial rectus muscle were recruited. After complete ophthalmic and orthoptic evaluation, the missing medial rectus muscle is screened using Anterior Segment Optical Coherence Tomography (ASOCT). In presence of a traceable muscle, its morphology, depth, and distance from a fixed anatomical landmarks were noted; in its absence, the status of other recti was noted. Intraoperatively, the features were confirmed and the intended intervention was performed. Results: The mean age of six patients was 25.66 ± 9.72 years, two with surgical trauma and four with penetrating trauma (66.66%). In five patients, the ASOCT traced the slipped medial rectus muscle successfully (83.33%); intraoperatively, the same was confirmed (within 1-2 millimeters) with favorable outcomes. ASOCT made a significant contribution in all subjects by reducing the number of interventions and muscle surgeries. Conclusions: In eyes with slipped medial rectus muscle, especially those which are within a finite distance from the angle can be traced using ASOCT. This approach impacts the outcomes in many ways.

Extraocular muscle enlargement of indeterminate cause in pediatric patients: case series and literature review.

PURPOSE: To specify the clinical characteristics of enlarged extraocular muscles of indeterminate cause in pediatric patients based on a case series and literature review. METHODS: The medical records of pediatric patients who presented between January 2019 and January 2022 with enlarged extraocular muscles, where the underlying cause could not be determined, were retrospectively reviewed. RESULTS: Four patients were included. The main reason for presentation was evaluation of abnormal head posture. Head tilt or turn with duction deficit was observed in all patients. The age of onset ranged from 6 months to 1 year. Two patients presented with esotropia and hypotropia; the other 2 patients, with large-angle esotropia. Orbital imaging was performed in all cases and revealed unilateral rectus muscle enlargement sparing the muscle tendon. All 4 patients were found to have an enlarged medial rectus muscle. In the 2 patients with hypotropia, the inferior rectus muscle was also involved. No underlying systemic or orbital disease was found. There were no changes in the orbit or extraocular muscles on follow-up imaging test. The intraoperative forced duction test revealed severe restriction in the direction of gaze opposite to the primary field of action of the enlarged muscles. CONCLUSIONS: Enlargement of extraocular muscles should be considered in the differential diagnosis when large-angle incomitant vertical or horizontal misalignment and abnormal head posture are observed in infancy.

Extraocular muscle volume index at the orbital apex with optic neuritis: a combined parameter for diagnosis of dysthyroid optic neuropathy.

OBJECTIVES: To evaluate the diagnostic performance of the extraocular muscle volume index at the orbital apex (AMI) and the signal intensity ratio (SIR) of the optic nerve in dysthyroid optic neuropathy (DON). METHODS: Clinical data and magnetic resonance imaging were collected retrospectively from 63 Graves' ophthalmopathy patients, including 24 patients with DON and 39 without DON. The volume of these structures was obtained by reconstructing their orbital fat and extraocular muscles. The SIR of the optic nerve and axial length of eyeball were also measured. The posterior 3/5 of the retrobulbar space volume was used as the orbital apex to compare parameters in patients with or without DON. Area under the receiver operating characteristic curve (AUC) analysis was used to select the morphological and inflammatory parameters with the highest diagnostic value. A logistic regression was performed to identify the risk factors of DON. RESULTS: One hundred twenty-six orbits (35 with DON and 91 without DON) were analyzed. Most of the parameters in DON patients were significantly higher than in non-DON patients. However, the SIR 3 mm behind the eyeball of the optic nerve and AMI had the highest diagnostic value in these parameters and are independent risk factors of DON by stepwise multivariate logistic regression analysis. Combining AMI and SIR had a higher diagnostic value than a single index. CONCLUSIONS: Combining AMI with SIR 3 mm behind the eyeball's orbital nerve can be a potential parameter for diagnosing DON. CLINICAL RELEVANCE STATEMENT: The present study provided a quantitative index based on morphological and signal changes to assess the DON, allowing clinicians and radiologists to monitor DON patients timely. KEY POINTS: The extraocular muscle volume index at the orbital apex (AMI) has excellent diagnostic performance for dysthyroid optic neuropathy. A signal intensity ratio (SIR) of 3 mm behind the eyeball has a higher AUC compared to other slices. Combining AMI and SIR has a higher diagnostic value than a single index.

Quantitative assessment of extraocular muscles in Graves' ophthalmopathy using T1 mapping.

OBJECTIVE: To evaluate the performance of T1 mapping in the characterization of extraocular muscles (EOMs) of Graves' ophthalmopathy (GO) patients and investigate its feasibility in assessing the response to glucocorticoid therapy in active GO patients. METHODS: A total of 133 participants (78 active GO, 23 inactive GO, 18 Graves' disease (GD) patients, and 14 healthy volunteers) were consecutively enrolled from July 2018 to December 2020. Native T1 (nT1) and postcontrast T1 (cT1) values of EOMs were measured and compared. The variations in T1 mapping metrics of EOMs were compared pre/post glucocorticoid treatment in 23 follow-up active GO patients. Logistic regression analysis and receiver operating characteristic (ROC) curve analysis were performed. RESULTS: The nT1 of EOMs in GO patients was higher than that in GD patients and healthy volunteers. The nT1 of superior rectus (SR) in active GO was higher than that in inactive GO patients, and it could be used as a potential marker of GO activity (OR: 1.003; 95% CI: 1.001, 1.004), with a diagnostic sensitivity of 86.3% and specificity of 43.7%. Meanwhile, the cT1 of SR, inferior rectus (IR), and medial rectus (MR) in inactive GO patients were higher than those in active GO patients. The nT1 of EOMs achieved sufficient diagnostic performance in evaluating the response to glucocorticoid therapy for follow-up active GO patients (AUC, 0.797; sensitivity, 71.9%; specificity, 85.7%). CONCLUSIONS: T1 mapping could quantitatively assess the activity of GO and the response to glucocorticoid therapy in active GO patients and may even potentially reflect the fibrosis of EOMs. CLINICAL RELEVANCE STATEMENT: T1 values can reflect the pathological status of the extraocular muscle. T1 mapping could help to quantitatively assess the clinical activity of GO and the response to glucocorticoid therapy in active GO patients. KEY POINTS: • Graves' ophthalmopathy patients had greater nT1 of extraocular muscles than Graves' disease patients and healthy volunteers, and nT1 of the superior rectus could be a potential marker of Graves' ophthalmopathy activity. • The cT1 of extraocular muscles in inactive Graves' ophthalmopathy patients was higher than that in active Graves' ophthalmopathy patients, and it might be associated with muscle fibrosis. • nT1 of extraocular muscles could offer sufficient diagnostic performance in evaluating the response to glucocorticoid therapy for follow-up active Graves' ophthalmopathy patients.

An atypical case of myopic strabismus fixus.

We present an atypical case of progressive fixed hypertropia in a patient with extreme myopia. Myopic strabismus fixus is typically characterized by progressive esotropia and hypotropia, which is caused by the protrusion of the posterior eyeball from the superotemporal quadrant of the extraocular muscle cone. In this case, the patient's right eye was fixed in a superomedial position, and the left eye was fixed and deviated upward. Magnetic resonance imaging revealed protrusion of a posterior scleral staphyloma inferotemporally in each eye. This case illustrates how the pattern of strabismus fixus caused by high myopia depends on the direction of the protrusion of the posterior pole and the resulting displacement of extraocular muscle paths.

Effective encoder-decoder neural network for segmentation of orbital tissue in computed tomography images of Graves' orbitopathy patients.

PURPOSE: To propose a neural network (NN) that can effectively segment orbital tissue in computed tomography (CT) images of Graves' orbitopathy (GO) patients. METHODS: We analyzed orbital CT scans from 701 GO patients diagnosed between 2010 and 2019 and devised an effective NN specializing in semantic orbital tissue segmentation in GO patients' CT images. After four conventional (Attention U-Net, DeepLab V3+, SegNet, and HarDNet-MSEG) and the proposed NN train the various manual orbital tissue segmentations, we calculated the Dice coefficient and Intersection over Union for comparison. RESULTS: CT images of the eyeball, four rectus muscles, the optic nerve, and the lacrimal gland tissues from all 701 patients were analyzed in this study. In the axial image with the largest eyeball area, the proposed NN achieved the best performance, with Dice coefficients of 98.2% for the eyeball, 94.1% for the optic nerve, 93.0% for the medial rectus muscle, and 91.1% for the lateral rectus muscle. The proposed NN also gave the best performance for the coronal image. Our qualitative analysis demonstrated that the proposed NN outputs provided more sophisticated orbital tissue segmentations for GO patients than the conventional NNs. CONCLUSION: We concluded that our proposed NN exhibited an improved CT image segmentation for GO patients over conventional NNs designed for semantic segmentation tasks.

Extraocular Muscle Enlargement in Acromegaly.

BACKGROUND: To determine whether acromegaly is associated with increased extraocular muscle (EOM) size at time of presentation. METHODS: Patients with a new diagnosis of acromegaly in a single tertiary care clinic with a CT scan that adequately delineated the EOMs were included. Control subjects were age- and sex-matched patients with a new diagnosis of nonfunctioning pituitary adenoma. Retrospective chart review was performed to extract baseline clinical and laboratory parameters including growth hormone, insulin-like growth factor 1, thyroid stimulating hormone, free T3, and free T4. A single neuroradiologist analyzed all CT scans and measured the maximum diameter and cross-sectional area of the superior rectus, inferior rectus, medial rectus, and lateral rectus in both eyes of all patients. RESULTS: We evaluated 17 patients with acromegaly and 18 control subjects. Mean maximum diameter of the superior, inferior, medial, and lateral recti were 4.80 mm (SD = 0.81), 4.67 mm (SD = 0.54), 4.86 mm (SD = 0.77), and 4.53 mm (SD = 0.70) respectively, in the acromegaly group. In the control group, they were 3.62 mm (SD = 0.58),3.71 mm (SD = 0.46), 3.66 mm (SD = 0.32), and 3.21 mm (SD = 0.44), respectively. The maximum diameter and cross-sectional area of all 4 EOMs measured in the acromegaly group were significantly larger ( P < 0.001) compared with the control group. CONCLUSIONS: Patients with acromegaly present with significantly enlarged EOMs compared with control subjects with nonfunctioning pituitary adenomas.

Eye Muscle MRI in Myasthenia Gravis and Other Neuromuscular Disorders.

INTRODUCTION: MRI of extra-ocular muscles (EOM) in patients with myasthenia gravis (MG) could aid in diagnosis and provide insights in therapy-resistant ophthalmoplegia. We used quantitative MRI to study the EOM in MG, healthy and disease controls, including Graves' ophthalmopathy (GO), oculopharyngeal muscular dystrophy (OPMD) and chronic progressive external ophthalmoplegia (CPEO). METHODS: Twenty recently diagnosed MG (59±19yrs), nineteen chronic MG (51±16yrs), fourteen seronegative MG (57±9yrs) and sixteen healthy controls (54±13yrs) were included. Six CPEO (49±14yrs), OPMD (62±10yrs) and GO patients (44±12yrs) served as disease controls. We quantified muscle fat fraction (FF), T2water and volume. Eye ductions and gaze deviations were assessed by synoptophore and Hess-charting. RESULTS: Chronic, but not recent onset, MG patients showed volume increases (e.g. superior rectus and levator palpebrae [SR+LPS] 985±155 mm3 compared to 884±269 mm3 for healthy controls, p < 0.05). As expected, in CPEO volume was decreased (e.g. SR+LPS 602±193 mm3, p < 0.0001), and in GO volume was increased (e.g. SR+LPS 1419±457 mm3, p < 0.0001). FF was increased in chronic MG (e.g. medial rectus increased 0.017, p < 0.05). In CPEO and OPMD the FF was more severely increased. The severity of ophthalmoplegia did not correlate with EOM volume in MG, but did in CPEO and OPMD. No differences in T2water were found. INTERPRETATION: We observed small increases in EOM volume and FF in chronic MG compared to healthy controls. Surprisingly, we found no atrophy in MG, even in patients with long-term ophthalmoplegia. This implies that even long-term ophthalmoplegia in MG does not lead to secondary structural myopathic changes precluding functional recovery.