Superior Oblique Research Articles

Evaluation of the Normal Measurements of Orbital Structures in Healthy Adult Individuals by Using a Magnetic Resonance Imaging Method

Background: This study aims to determine the normal values of orbital structures according to sex in healthy adults. Methods: Diameters of extraocular muscles, the width of the optic nerve sheath diameter, the length of the inter-zygomatic line, ocular bulb length, and globe position were measured in the T1-weighed MR (magnetic resonance) images in 204 orbits of 102 individuals. Results: The mean values of the diameters of the extraocular muscles in males and females were as follows: medial rectus, 3.96 ± 0.52 and 3.58 ± 0.53 mm; lateral rectus, 3.47 ± 0.61 and 3.15 ± 0.48 mm; inferior rectus, 4.47 ± 0.53 and 4.07 ± 0.48 mm; superior rectus, 4.44 ± 0.64 and 4.01 ± 0.56 mm; and superior oblique, 3.68 ± 0.49 and 3.45 ± 0.44 mm. The length of the interzygomatic line in males and females were 102.68 ± 3.89 and 96.95 ± 3.4 mm, the ocular bulb length was 23.33 ± 1.32 and 22.83 ± 1.1 mm, the globe position was 7.66 ± 1.33 and 7.3 ± 1.39 mm, and the width of the optic nerve sheath diameter was 4.65 ± 0.62 and 4.28 ± 0.51 mm, respectively. All measurements were significantly greater for males than for females (p < 0.05). Conclusions: We believe that a practical and quantitative method will be provided by this study for the diagnosis and determination of the normative values of orbital structures.

Use of a Microelectromechanical Systems Sensor for Objective Measurements of Abnormal Head Posture in Congenital Superior Oblique Palsy Patients.

The purpose of this study was to design an objective method for measurement of head positions as achieved with use of a microelectromechanical systems (MEMS) sensor. In addition, to use this system to observe the abnormal head position (AHP) in patients with congenital superior oblique palsy (SOP) before and after their surgery. An MEMS sensor was designed for recording of the pitch, roll, and yaw values of the head position in real time. The MEMS sensor was then fixed on the synoptophore from -30 degrees to +30 degrees positions horizontally and vertically to test the accuracy of these measurements. Then, we tested 13 participants with AHP using the MEMS method and the photographic method and compared their correlations. Finally, the pitch, roll, and yaw values of head positions were measured using this MEMS sensor in 31 patients with congenital SOP as performed before and after their surgery. The MEMS sensor (LPMS-B2; Alubi, Guangzhou, China; 400 hertz [Hz]), as based on the theory of a gyroscope, was designed and connected to a smartphone via Bluetooth. It was able to conveniently record the patient's pitch, roll, and yaw head positions in real time, recordings which were consistent with the scales of the synoptophore (P > 0.05) and good correlations with the photographic method (P < 0.001). The main preoperative AHP in patients with SOP was roll (22/31, 71%). Pre- and postoperative vertical deviations were 16.4 ± 7.3 prism diopters (PD) and 4.1 ± 4.2 PD, respectively (P = 0.001). The AHP in patients with SOP was positively correlated with the angle of extorsion in the dominant eye (P = 0.01), rather than that of the vertical deviation. The MEMS sensor described in this report is a simple, practical, and accurate objective device for use in head position measurements. In patients with SOP, the AHP is related to the angle of extorsion in the dominant eye. The MEMS sensor was designed as a micro-wireless dynamic high-precision device for AHP measurement, which has the potential for use in a clinic.

Anterior Nasal Superior Oblique Tendon Syndrome: A Case Series

PurposeTo evaluate the clinical characteristics and management of patients with an anteriorly and nasally inserted superior oblique tendon. DesignRetrospective interventional case series. MethodsInstitutional clinical records between 2020 and 2024 were retrospectively reviewed for 9 consecutive patients in whom the superior oblique (SO) tendon was inserted anterior to the equator and nasal to the superior rectus muscle. Information collected included age, sex, ocular and surgical history, preoperative and postoperative data (ophthalmologic examinations, strabismus measurements, ductions and versions), intraoperative findings, need for additional surgery, and follow-up time. ResultsAll nine patients were found to have an anomalous insertion of the SO tendon. Three were of congenital origin and six were acquired following ocular surgery. Among the acquired cases, all but one resulted from incarceration of the tendon from post-surgical scar tissue formation. The remaining acquired case was due to a prior deliberate anterior and nasal transposition of the superior oblique. This case series demonstrated varying degrees of vertical deviations, lateral incomitance, and limited depression. Repositioning the SO to its normal insertion site yielded equivocal improvement in ocular alignment. ConclusionAnterior nasal superior oblique tendon syndrome is a rare clinical entity characterized by an anti-depressor effect. Vertical deviations, hypertropia worse in downgaze, limited depression worse in adduction for congenital cases and in abduction for acquired cases, and lateral incomitance may be indicative of this anomaly. In acquired cases following surgery, additional findings may include limited depression worse in abduction, esotropia in abduction, V-pattern esotropia, and enophthalmos in downgaze. Surgical repositioning of the SO along its normal anatomical trajectory is recommended for treatment. However, outcomes may be variable and achieving a complete resolution of this syndrome can be challenging.

One- vs Two- vertical muscle surgery in the management of unilateral superior oblique muscle palsy with hypertropia over 20 PD

ABSTRACT Purpose: To compare the surgical outcomes of One- versus Two-vertical muscle surgery in patients with unilateral superior oblique muscle palsy (SOP) with primary position hypertropia (HT) over 20 PD. Patients in Group 1 underwent inferior oblique anterior transposition plus resection (IOATR), while patients in Group 2 underwent inferior oblique anterior transposition (IOAT) along with contralateral inferior rectus (IR) recession. Methods: Medical data of all SOP patients treated by either procedure from 2000 to 2023 in our strabismus center were recruited. We compared surgical outcomes between Group 1 and Group 2 by analyzing HT correction, rate of under-correction, and over-correction. Results: The study included 33 patients in Group 1 and 23 in Group 2. Both groups were similar in age, sex, etiology, affected side, diplopia, and head tilt. Group 2 achieved higher HT correction in all measured gazes. Group 1 had a higher risk of under-correction (18.18% in Group 1 vs 8.69% in Group 2) while Group 2 had a higher rate of over-correction (21.73% vs 0% in Group 1). Conclusion: In patients with severe unilateral SOP, Two-vertical muscle surgery achieved higher amounts of HT correction in all gazes despite a significantly higher risk of over-correction.

Orbital Involvement as an Initial Presentation of Sinonasal Neuroendocrine Carcinoma

Purpose: To present a case of sinonasal neuroendocrine cancer initially manifesting with orbital involvement.Case summary: A 63-year-old female patient visited a neuro-ophthalmologic clinic due to a 3-week history of decreased visual acuity (VA), color vision abnormalities, and swelling of the upper eyelid in right eye. Best-corrected VA (BCVA) in the right eye was 0.8. Clinical findings included a relative afferent pupillary defect, restricted eye movement in lateral, superior, and medial gaze, and exophthalmos in the right eye. Wide-field fundus photography and optical coherence tomography indicated swelling of right optic disc. Magnetic resonance imaging was performed revealing a mass invading nasal cavity, sinus, and right orbital apex, and compressing the medial rectus, inferior rectus, superior oblique, and optic nerve. An otolaryngological nasal biopsy was conducted and immunohistochemical staining showed positive results for Ki-67, NSE, p16, P-53, and CD56, leading to a diagnosis of small cell neuroendocrine carcinoma with an irreducible tumor stage. Prior to initiation of treatment (concurrent chemoradiotherapy, CCRT), there was rapid worsening of VA and eye movement in the right eye. CCRT commenced alongside high-dose steroid treatment. One month following treatment, the BCVA of the right eye improved and protrusion of the right eye resolved. Six months after starting CCRT, a contrast-enhanced orbital computed tomography scan showed no residual lesion. The BCVA of the right eye stabilized at 0.3 with complete recovery of color vision and eye movement.Conclusions: Neuroendocrine cancer should be considered as a possible diagnosis in cases of rapidly progressing compressive optic neuropathy.

Surgical outcomes in patients with congenital superior oblique palsy: A comparison between clinical and radiological diagnosis

PurposeThe diagnosis of superior oblique (SO) palsy can be achieved by examining the radiological and clinical characteristics. Despite their usefulness, the radiological and clinical methods are not always aligned to each other. The objective of this research is to analyze the surgical results of eyes with SO palsy, based on whether the diagnosis was made radiologically or clinically. DesignA prospective study, conducted at a single tertiary hospital. MethodsFollowing the diagnosis of SO palsy, either through clinical assessment or radiological imaging, the patients were categorized into three distinct groups according to their clinical measurements and MRI findings. Group 1 exhibited consistent clinical measurements and MRI findings indicating SO palsy, whereas Group 2 displayed clinical measurements without MRI confirmation. In contrast, Group 3 presented inconclusive measurements, but MRI scans revealed signs of atrophy. Patients underwent inferior oblique (IO) myectomy with and without contralateral inferior rectus recession and ocular deviation before and after myectomy were collected. ResultsThe study included 49 patients with congenital unilateral SO palsy (average age: 30 years). Out of 35 patients who tested positive across all three stages of the test, 15 did not show notable muscle atrophy in their MRI findings. In contrast, among those who displayed muscle atrophy in their MRI scans, 58.8 % had positive outcomes in all steps of the three-step assessment. Group 1 and 3 displayed a reduced muscle volume measuring 110.988 ± 42.49 mm³ and 91.5 ± 56.8 mm³, respectively, on the affected side. Group 2 showcased a muscle volume of 184.1 ± 44.64 mm³ on the affected side. In all three groups with SO palsy eyes who underwent IO myectomy, there was a reduction in hypertropia in the primary position, with no statistically significant differences observed among the groups (P = 0.1). All five patients with SO palsy who underwent IO myectomy with contralateral inferior rectus recession were classified in group 3, and they exhibited a significant reduction in hypertropia postoperatively. ConclusionComparable results can be attained through IO surgery in patients with SO palsy, regardless of whether they are diagnosed through clinical or radiological means.

Surgical treatment of unilateral acquired superior oblique muscle palsy in adults by inferior oblique belly transposition: a retrospective analysis.

Evaluate and analyze the efficacy of inferior oblique belly transposition (IOBT) in treating adult patients with diplopia and small-angle hypertropia caused by mild to moderate inferior oblique overaction (IOOA) secondary to acquired superior oblique palsy (SOP). Nine adult patients with diplopia and small-angle hypertropia associated with mild to moderate IOOA secondary to unilateral acquired SOP were included in the current retrospective study. All patients received the IOBT procedure between February 2019 and May 2023 at The Second People's Hospital of Jinan and were followed up for more than 6months after the surgery. During the procedure, the belly of the inferior oblique muscle was fixed to the sclera at 5mm posterior to the temporal insertion of the inferior rectus muscle. The following indicators were reviewed pre- and post-surgery: the vertical deviation (VD) in the primary position and in the Bielschowsky test, the fovea disc angle (FDA) of the affected eye, changes in IOOA, and diplopia. After IOBT, the VD in the primary position decreased from 7.22△ ± 1.72△ (range 4△-10△) to 1.22△ ± 1.30△ (range 0△-3△). The VD in the Bielschowsky test decreased from 13.00△ ± 1.80△ to 3.22△ ± 1.09△. The FDA decreased from 10.02° ± 3.34° to 6.26° ± 1.91°. The grade of IOOA was reduced from 2.00 (1.00, 2.00) to 0.00 (0.00, 1.00). All changes were statistically significant (P < 0.001 or P = 0.006). Diplopia was resolved completely for all patients. IOBT can effectively treat adults with diplopia and small-angle hypertropia caused by mild to moderate IOOA secondary to acquired SOP.

Extraocular Muscle Enlargement in Thyroid Eye Disease Using Volumetric Analysis.

It is commonly taught that thyroid eye disease (TED) causes enlargement of the extraocular muscles (EOMs) in the following descending order: inferior rectus (IR), medial rectus (MR), superior rectus (SR), lateral rectus (LR), superior oblique (SO) and inferior oblique (IO). However, with recent literature challenging this notion, we aimed to compare EOMvolumes in our cohort of TED patients. Methods: We conducted a retrospective, non-randomized case-control study. Twenty-eight orbits from 28 unique patients with TED who had high-resolution CT scans were compared to 31 normal orbits, all from a single academic institution. Orbital soft tissues were manually segmented using ITK-SNAP 3.8.0 (http://itksnap.org), and soft tissue volumes of the control and TED orbits were compared using independent-sample t-tests. Of the TED orbits, 54% of SR/levator palpebrae superioris complex volumes (SRC) and 50% of IR volumes were greater than two standard deviations above the normal orbit average. Compared to controls, the mean SRC volume in TED subjects was 2.3 times enlarged, followed by the IR (2.1 times), SO (1.8 times), MR (1.7 times), LR (1.6 times), IO (1.6 times), and orbital fat (1.4 times) (p < 0.01 for all). Conclusions: Our findings suggest that contrary to previous teaching, the SRC may be the most severely affected in TED.

The tortuous course of the anterior ethmoidal artery in the orbit: A cadaveric study

AimThe study aimed to define the coursing pattern of the anterior ethmoidal artery (AEA) in the orbit to minimize complications during endoscopic interventions. Materials and methodsA total of ten formalin-fixed cadaveric halves were included in the study. Orbital regions were shown with a superior approach. The superior rectus and superior oblique muscles, as well as the connective tissue and vessels were removed to observe the path of the anterior ethmoidal artery. Measurements such as the width of the artery, the anterior-posterior length of the U formation, the length of the intraorbital part of the ophthalmic artery, and the distance of the AEA from its opthalmic origin to the anterior ethmoidal foramen were made. ResultsTen of the AEAs originated from the ophthalmic artery. The AEA branches originated from the ophthalmic artery approximately 18.4 mm after the orbital artery entered the orbital, and the mean width of the AEAs was 0.82 mm. In seven of the total anterior ethmoidal arteries, they coursed in the intraethmoidal cavities below the cranial base. The mean distance from the origin of AEAs to the medial wall of the orbit was 4.9 mm. After leaving the ophthalmic artery, seven of the AEAs were coursing forward and turned back ('U' turn formation), which have proximately 1.5 mm in anteroposterior direction. ConclusionThe anterior ethmoidal artery is 0.8 mm wide, originates from the distal part of the ophthalmic artery, entering the orbit after a 1.5 mm U-turn.

Genome-Wide Association Study with Three Control Cohorts of Japanese Patients with Esotropia and Exotropia of Comitant Strabismus and Idiopathic Superior Oblique Muscle Palsy.

Esotropia and exotropia in the entity of comitant strabismus are multifactorial diseases with both genetic and environmental backgrounds. Idiopathic superior oblique muscle palsy, as the predominant entity of non-comitant (paralytic) strabismus, also has a genetic background, as evidenced by varying degrees of muscle hypoplasia. A genome-wide association study (GWAS) was conducted of 711 Japanese patients with esotropia (n= 253), exotropia (n = 356), and idiopathic superior oblique muscle palsy (n = 102). The genotypes of single nucleotide polymorphisms (SNPs) were determined by Infinium Asian Screening Array. Three control cohorts from the Japanese population were used: two cohorts from BioBank Japan (BBJ) and the Nagahama Cohort. BBJ (180K) was genotyped by a different array, Illumina Infinium OmniExpressExome or HumanOmniExpress, while BBJ (ASA) and the Nagahama Cohort were genotyped by the same Asian array. After quality control of SNPs and individuals, common SNPs between the case cohort and the control cohort were chosen in the condition of genotyping by different arrays, while all SNPs genotyped by the same array were used for SNP imputation. The SNPs imputed with R-square values ≥ 0.3 were used to compare the case cohort of each entity or the combined entity with the control cohort. In comparison with BBJ (180K), the esotropia group and the exotropia group showed CDCA7 and HLA-F, respectively, as candidate genes at a significant level of p < 5 × 10-8, while the idiopathic superior oblique muscle palsy group showed DAB1 as a candidate gene which is involved in neuronal migration. DAB1 was also detected as a candidate in comparison with BBJ (ASA) and the Nagahama Cohort at a weak level of significance of p < 1 × 10-6. In comparison with BBJ (180K), RARB (retinoic acid receptor-β) was detected as a candidate at a significant level of p < 5 × 10-8 in the combined group of esotropia, exotropia, and idiopathic superior oblique muscle palsy. In conclusion, a series of GWASs with three different control cohorts would be an effective method with which to search for candidate genes for multifactorial diseases such as strabismus.

Clinical characteristics and surgical outcomes in patients with superior oblique muscle palsy: a retrospective study on 1057 patients

BackgroundTo evaluate the clinical findings of patients with SOP who underwent surgery.MethodsThis historical cohort study was performed on 1057 SOP patients managed with surgery in Farabi Hospital, Iran, from 2011 to 2022.ResultsThere were 990 (93.7%) patients with unilateral SOP with the mean age of 21.8 ± 14.8 years. Of these, 715 patients (72.2%) were diagnosed with congenital SOP, and 275 patients (27.8%) had acquired SOP (P < 0.001). In contrast, 67 (6.3%) patients were diagnosed with bilateral SOP, with the mean age of 19.4 ± 15.6 years. Among these, 18 cases exhibited the masked type. The mean angle of vertical deviation in primary position at far in unilateral and bilateral cases was 15.6 ± 8.3 and 13.3 ± 9.1 △, respectively (P < 0.001). In unilateral cases, abnormal head posture (AHP) was detected in 847 (85.5%) patients and 12 (1.2%) had paradoxical AHP. Amblyopia was found in 89 (9.9%) unilateral and 7 (10.3%) bilateral cases. Solitary inferior oblique myectomy, was the most common surgery in both unilateral (n = 756, 77.1%) and bilateral (n = 35, 52.2%) patients. The second surgery was performed for 84 (8.6%) unilateral and 33 (49.3%) bilateral cases (P < 0.001). The prevalence of amblyopia and the mean angle of horizontal deviation were significantly higher in patients who needed more than one surgery (all P < 0.05).ConclusionCongenital SOP was more than twice as frequent as acquired SOP and about 90% of unilateral and 50% of bilateral cases were managed with one surgery. Amblyopia and significant horizontal deviation were the most important factors for reoperation.Trial registrationThe Institutional Review Board approval was obtained from the Tehran University of Medical Sciences (IR.TUMS.FNM.REC.1400.012) and this study adhered to the tenets of the Declaration of Helsinki and HIPAA.

Small tuck for superior oblique palsy

PurposeTo investigate the surgical outcomes of small superior oblique (SO) tuck—denoting minimal tendon laxity—in patients with unilateral SO palsy. MethodsThe medical records of consecutive patients treated with ≤6 mm SO tuck from 2000 to 2018 at Kellogg Eye Center, University of Michigan, were reviewed retrospectively. Tendon tucks were performed to a fairly uniform tension in an amount that just eliminated slack in the tendon. Pre- and postoperative motility measurements were compared. Patients were excluded if they had a history of prior strabismus surgery or concurrent vertical rectus or inferior oblique surgery. ResultsA total of 27 cases (14 males) met inclusion criteria. The median age at surgery was 47 years (range 3–74 years). The mean SO tuck (total, both arms of tuck) was 4.9 mm (range, 2–6 mm). After surgery, median hypertropia decreased from 9Δ to 1Δ in primary position and from 20Δ to 4Δ in the SO field of action (contralateral downgaze). Lateral incomitance (difference in hypertropia between contralateral and ipsilateral gaze) decreased from 10Δ to 2Δ (P < 0.001 in each case). Six patients had diplopia in upgaze postoperatively that was not symptomatic enough to require reoperation. Six patients had residual hypertropia requiring additional surgery. ConclusionsSmall SO tuck provided disproportionate correction of hypertropia in the SO field of action and nearly eliminated lateral incomitance without producing unacceptable iatrogenic Brown syndrome. Even in the absence of tendon laxity, SO tuck was a good surgical option for SO palsy in our cohort where there was marked lateral incomitance and the greatest deviation was in the SO field of action.

Boergen modification of Harada-ito surgery with and without vertical muscle surgery for acquired unilateral superior oblique muscle palsy.

The purpose is to report the results of the Boergen modification of the Harada-Ito procedure with and without simultaneous vertical muscle surgery in patients with acquired unilateral superior oblique muscle palsy. Files of patients with acquired unilateral superior oblique muscle palsy who were treated with Boergen modification of the Harada-Ito procedure were studied retrospectively. For each patient, age at the time of surgery, the presence of diplopia, compensatory head posture, and ocular deviation before and after surgery were retrieved. Results were evaluated 6 months after surgery. A total of 12 patients with a mean age of 32 years at the time of surgery (range 15-45 years) were included. The underlying etiology was head trauma in eleven patients. The modified Harada-Ito procedure alone was done for three cases (Group 1), and a simultaneous combination of this procedure and vertical muscle surgery was performed in nine patients (Group 2). The average intorsional effect in the primary position was 9.2° (8° in Group 1 and 9.6° in Group 2). The average correction of hypertropia in the primary position was 8.2 prism diopters (PD) (1 PD in Group 1 and 10.6 PD in Group 2). Diplopia in the primary position and downgaze were resolved in eleven patients and ten patients, respectively. Four patients had a compensatory head tilt at their last follow-up. Boergen modification of the Harada-Ito procedure, alone and combined with vertical muscle surgery, successfully corrected primary position diplopia in the majority of the patients.

Correlation between extraocular muscle enlargement and thyroid autoantibodies in thyroid eye disease

PurposeThis study aimed to investigate the factors affecting extraocular muscle enlargement in thyroid eye disease (TED).Study designRetrospective study.MethodsThe thyroid-stimulating hormone (TSH) receptor antibody (TRAb), thyroid-stimulating antibody (TSAb), antithyroid peroxidase antibody (ATPO), and antithyroglobulin antibody (ATG) levels in patients diagnosed with TED who underwent orbital magnetic resonance imaging were assessed. The control group comprised the contralateral eye of patients who underwent orbital magnetic resonance imaging (MRI) for unilateral eyelid tumors or orbital disease. The thickness of the bilateral rectus muscles and superior oblique muscles was measured on orbital MRI. Muscle enlargement was classified as unilateral/bilateral and symmetric/asymmetric. The effects of age, sex, smoking history, TSH, thyroid hormone, and thyroid autoantibodies on the muscle thickness and number of enlarged muscles were assessed by use of simple and multiple regression analyses.ResultsThe TED and control groups comprised 41 and 44 cases, respectively. The positivity rate of TSAb in patients with TED was 92.7% higher than that of the other autoantibodies. Muscle enlargement was observed in 29 of the 41 cases (70.7%). Older age and higher TSAb levels were identified as significant factors affecting the total muscle thickness and number of enlarged muscles. Bilateral muscle enlargement and asymmetrical muscle enlargement were observed in 17 (58.6%) and 23 (79.3%) of the 29 cases, respectively. The TSAb levels and age had no significant effect on the type of muscle enlargement.ConclusionsTSAb showed significant associations with extraocular muscle enlargement. Measurement of TSAb, rather than of TRAb, may be more useful for diagnosing extraocular muscle enlargement in patients with TED.

Isolated Superior Oblique Palsies Secondary to Trochlear Schwannomas in the Absence of Systemic Neurofibromatosis (P5-10.005)

Isolated Superior Oblique Palsies Secondary to Trochlear Schwannomas in the Absence of Systemic Neurofibromatosis (P5-10.005)

Normative measurements of orbital structures on magnetic resonance images; a cross-sectional study with mini review of the literature.

Awareness of normative values of extra orbital structures would provide useful information to interpret the radiological images better and use them for diagnostic purposes. This study aimed to reveal the average values of major extraocular structures measured on magnetic resonance images. In this retrospective cross-sectional study, magnetic resonance (MR) images of 256 orbits of 128 patients were re-interpreted regarding the measurements of major orbital structures. Extraocular muscles, superior ophthalmic vein, and optic nerve-sheath complex were measured on orbital MR images of these patients. The data distributions were presented by box-plot analyses for each parameter, and the measurement results were analyzed regarding gender and age groups. Lateral rectus muscle thickness (LR), inferior rectus muscle thickness (IR), globe position (GP), and interzygomatic line (IZL) values were higher in the male group than in the female group (p values were < 0.001, 0.003, 0.020, and < 0.001 respectively). LR, the thickness of the superior group muscles (SUP GR), IR, superior oblique muscle thickness (SOBL), and the thickness of optic nerve-sheath complex (ON) values indicated a significant relationship between age groups. There was a significant, positive, and low-level correlation between age and LR, SUP GR, and IR values (p values were < 0.001, 0.001, and < 0.001, respectively). This study provides quantitative data on normative values of orbital structures with gender and age group comparisons. Clinicians or surgeons can easily use the measured values to gather diagnostic information from the orbital region.

Extraocular muscle electromyographic recordings for intraoperative monitoring of cranial nerves III, IV, and VI: a single-center experience with intraorbital electrodes.

The objective of this study was to describe the quantitative features of intraoperative electromyographic recordings obtained from cranial nerve III, IV, and VI neuromonitoring using 25-mm intraorbital electrodes, in the larger context of demonstrating the practicality of this technique during neurosurgical cases. A 25-mm-long shaft-insulated intraorbital needle electrode is routinely used at the authors' institution for extraocular muscle (EOM) electromyographic monitoring of the inferior rectus, superior oblique, and/or lateral rectus muscles when their function is at risk. Cases monitored between January 1, 2021, and December 31, 2022, were reviewed for patient demographics, tumor location and pathology, EOMs monitored, pre- and postoperative examination, and complications from electrode placement. Compound muscle action potentials on triggered electromyography, as well as neurotonic discharges on free-run electromyography, were described quantitatively. There were 141 cases in 139 patients reviewed during the 24-month time span, with 278 EOMs monitored (inferior rectus/superior oblique/lateral rectus muscles 68/68/142). Triggered electromyography yielded biphasic or triphasic compound muscle action potentials from EOMs with a mean onset latency of 1.51 msec (range 0.94-3.22 msec), mean maximal peak-to-trough amplitude of 1073.93 μV (range 76.75-7796.29 μV), and high specificity for the channel in nearly all cases. Neurotonic discharges were recorded in 30 of the 278 EOMs (with all 3 muscles represented) and associated with a greater incidence of new or worsened ophthalmoparesis (OR 4.62, 95% CI 1.3-16.4). There were 2 cases of small periorbital ecchymosis attributed to needle placement; additionally, 1 case of needle-related intraorbital hematoma occurred after the review period. The 25-mm shaft-insulated intraorbital electrode facilitates robust and consistent electromyographic recordings of EOMs that are advantageous over existing techniques. Combined with the relative ease of needle placement and low rate of complications, the technique is practical for neuromonitoring during craniotomies.

The algorithm of diagnosis and surgical treatment of Brown’s syndrome

Introduction. Brown’s syndrome (BS) is a rare type of unconcomitant strabismus, which is often interpreted by practicing ophthalmologists as a paralytic form. The difficulty of diagnosis is due to the similarity of clinical manifestations with a number of other oculomotor disorders. This leads to a late, and most importantly, tactically incorrect choice of surgical treatment method. Purpose: Development of an algorithms for differential diagnosis and surgical treatment of Brown syndrome. Materials and methods. The authors analyzed the experience of diagnosing and treating 99 patients with Brown’s syndrome. The follow-up period was 13 years, from May 2010 to May 2023. Among the examined patients, 35 (35 %) were male and 64 (65 %) were female. The median age was 7.19 ± 0.87 years, the oldest at the time of the study was 45 years old, and the youngest was 1.5 years old. All patients underwent standard ophthalmologic and strabismal examinations. In patients of verbal age, the nature of vision was examined (Worth test, Bagolini test, double Maddox test). All operated patients underwent a cyclotorsion test intraoperatively under general anesthesia to confirm the diagnosis and choose a surgical method. Surgical treatment was carried out in 60 cases of unilateral and 5 cases of bilateral BS (a total of 65 patients aged 2 to 45 years; 69 eyes). Tenotomy and tenectomy of the superior oblique muscle (ECM) were performed in 53 cases, prolongation and recession with prolongation of the ECM in 16 cases. Results. Clinical signs have been systematized, algorithms for differential diagnosis and surgical treatment have been developed, which make it possible to timely identify Brown’s syndrome and carry out stage-by-stage pathogenetically based surgical treatment. The results are presented in the form of sequential action schemes (algorithms) that will help practitioners in making a diagnosis and determining the correct tactics of surgical treatment. Conclusions. Brown syndrome has characteristic differential features and requires staged surgical treatment. Developed algorithms to obtain high functional and cosmetic results.

Clinical effect of superior oblique re-tucking for recurrent or residual compensatory head position

Objective: To evaluate the effects of re-tucking the superior oblique muscle on recurrent or residual compensatory head position. Methods: A retrospective case series study was conducted. 12 recurrent or residual compensatory head position patients (12 eyes) with congenital superior oblique palsy who underwent superior oblique re-tucking in Tianjin Eye Hospital from March 2015 to February 2021 were included. All patients had a history of superior oblique tucking procedure and showed signs of superior oblique muscle palsy without inferior oblique muscle overaction. During surgery, the Guyton forced duction test is used to evaluate the relaxation of the superior oblique muscle tendon, which affects the re-tucking length of the muscle.Their head position, vertical deviation, eye movement, fovea-disa angle, and Bielschowsky head tilt test were assessed pre-and post-surgery. Statistical analysis was performed using ttest and paired samples Wilcoxon signed rank test. Results: Out of the 12 patients, 8 were male and 4 were female, aged between 2 and 9 years. The initial surgery was done at age 6, with a superior oblique recession length of (7.17±1.03) mm. Recurrent head tilt occurred in 11 patients after (3.82±0.98) months postoperatively, and 1 patient had residual head tilt, with a followup period of six months or more. Ocular motility examination revealed underaction of the superior oblique muscle, positive Bielschowsky's head tilt test, and Guyton forced duction tese indicating relaxation of the paralyzed superior oblique muscle tendon. Scar adhesion was observed at the stop of the superior oblique muscle, as well as the previous sutures. The scar and the sutures around the stop of the superior oblique muscle were released, the mean re-tucking amount was(7.83±1.59)mm. Follow-up at 12 to 18 months postoperatively showed disappearance of compensatory head position, significant improvement in superior oblique muscle lag, normal ocular motility, and no occurrence of Brown syndrome. The results of Bielschowsky head tilt were negative in 9 cases and still positive in 3 cases after superior oblique re-tucking. The primary vertical deviation was 2.5 (2.0, 5.3) prism diopter pre-operatively and 1 (0, 1) prism diopter post-operatively, respectively. The difference was statistically significant (U=6.00, P<0.001). The total amount of FDA in both eyes was (-22.04±5.47)° and (-15.27±6.08)° pre-and post-operatively, respectively. The difference was statistically significant (t=2.87, P=0.009). All 12 patients have normal eye movement after superior oblique re-tucking procedure. All patients had no compensatory head position at last follow-up. Conclusions: Superior oblique re-tucking is suitable for patients with relaxation of the superior oblique muscle tendon and extrocular rotation as the main sign. It can effectively and safely correct the recurrent or residual compensatory head position after re-tucking the superior oblique muscle.

The tortuous course of the anterior ethmoidal artery in the orbit: A cadaveric study

AimThe study aimed to define the coursing pattern of the anterior ethmoidal artery (AEA) in the orbit to minimize complications during endoscopic interventions. Materials and methodsA total of ten formalin-fixed cadaveric halves were included in the study. Orbital regions were shown with a superior approach. The superior rectus and superior oblique muscles, as well as the connective tissue and vessels were removed to observe the path of the anterior ethmoidal artery. Measurements such as the width of the artery, the anterior-posterior length of the U formation, the length of the intraorbital part of the ophthalmic artery, and the distance of the AEA from its opthalmic origin to the anterior ethmoidal foramen were made. ResultsTen of the AEAs originated from the ophthalmic artery. The AEA branches originated from the ophthalmic artery approximately 18.4 mm after the orbital artery entered the orbital, and the mean width of the AEAs was 0.82 mm. In seven of the total anterior ethmoidal arteries, they coursed in the intraethmoidal cavities below the cranial base. The mean distance from the origin of AEAs to the medial wall of the orbit was 4.9 mm. After leaving the ophthalmic artery, seven of the AEAs were coursing forward and turned back ('U' turn formation), which have proximately 1.5 mm in anteroposterior direction. ConclusionThe anterior ethmoidal artery is 0.8 mm wide, originates from the distal part of the ophthalmic artery, entering the orbit after a 1.5 mm U-turn.