1
|
Shen T, Yang R, Kang Y, Ye Q, Wen Y, Wen F, Yan J. Inferior displacement of the lateral rectus muscle insertion in exotropia with mild V-pattern or vertical deviation. Graefes Arch Clin Exp Ophthalmol 2024; 262:267-279. [PMID: 37606824 DOI: 10.1007/s00417-023-06207-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/17/2023] [Accepted: 08/11/2023] [Indexed: 08/23/2023] Open
Abstract
BACKGROUND To describe clinical features and intraoperative findings of the patients with exotropia who presented mild V-pattern or vertical deviation, and to investigate the surgical outcomes of anatomical relocation of inferiorly displaced lateral rectus (LR) muscle insertion. METHODS Detailed ophthalmological evaluations were obtained in 42 consecutive patients, and the horizontal rectus muscle insertions were detected intraoperatively. The displaced insertion of LR muscle was corrected accompanied with classic recession-resection procedure. RESULTS The inferiorly displaced LR muscle insertions were detected in 19 patients (Group A), while the remaining 23 patients (Group B) had normal insertions. The mean distance of displaced insertion from the normal position was 2.92 ± 1.05 mm (range: 1.0-4.0). Mild V-pattern was more common in Group A (78.9%, 15/19) than Group B (47.8%, 11/23), and the magnitude of V-pattern in Group A (6.16 ± 3.91 PD) was also greater than Group B (3.43 ± 3.92 PD). The fundus extorsions of the affected eyes (9.68 ± 4.77 °) were greater than the contralateral eyes (5.91 ± 5.82 °) in Group A. At the 2 months follow-up, mild V-pattern and mild vertical deviation were corrected by upward transposition. The significant correlations were identified between the pre-operative misalignments and the amounts of misalignments correction. CONCLUSIONS Nearly half of the cases with mild V-pattern or vertical deviation resulted from the inferiorly displaced LR muscle insertion, so the intraoperative exploration of the LR muscle insertion is strongly suggested. Upward transposition may effectively correct both the mild V-pattern and vertical deviation.
Collapse
Affiliation(s)
- Tao Shen
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Ruijun Yang
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Ying Kang
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Qingqing Ye
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Yun Wen
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Feng Wen
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Jianhua Yan
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China.
| |
Collapse
|
2
|
Demer JL, Clark RA. Masquerading Superior Oblique Palsy. Am J Ophthalmol 2022; 242:197-208. [PMID: 35618024 PMCID: PMC9991863 DOI: 10.1016/j.ajo.2022.05.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 05/15/2022] [Accepted: 05/16/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE We evaluated patients with hypertropia compatible with a diagnosis of superior oblique (SO) palsy to ascertain whether the 3-step test (3ST) can distinguish SO atrophy characteristic of trochlear nerve pathology from masquerading conditions. DESIGN Prospective cross-sectional study. METHODS In an academic practice, we performed quasi-coronal plane, surface coil magnetic resonance imaging in 83 patients clinically diagnosed with SO palsy. We evaluated alignment, SO cross-sectional area, SO contractility, and rectus muscle pulley positions. RESULTS A total of 57 patients with mean age 39 years (SD = 21 years) had unilateral SO palsy manifested by SO atrophy (22 congenital and 35 acquired). There was normal SO size in 26 patients with an average age of 39 years (SD =16 years) considered masquerades (8 congenital and 18 acquired). Maximum palsied SO cross-section averaged 9.5 ± 3.8 mm2, less than 18.4 ± 3.9 mm2 contralaterally (P < 10-24). In masquerades, maximum hypertropic SO cross-section was 20.7 ± 3.1 mm2, which was not different from the hypotropic SO or the contralesional muscle in SO palsy. Head tilt testing in masquerades was indistinguishable from SO palsy. In SO palsy, central hypertropia averaged 13.2 ± 9.4Δ, increasing to 21.1 ± 14.0Δ in ipsilateral tilt, and decreasing to 4.3 ± 5.3Δ in contralateral tilt. In masquerades, central hypertropia averaged 13.1 ± 8.7Δ, and was 17.7 ± 11.1Δ in ipsilateral and decreasing to 4.9 ± 5.1Δ in contralateral tilt. Upright hypertropia was larger at 17.7 ± 9.9Δ in congenital than 12.0 ± 8.4Δ in acquired SO palsy (P = 0025) but was indistinguishable from congenital masquerades. Contractile change in SO cross-section was bilaterally similar in masquerades. Relevant coordinates of rectus pulleys were similar bilaterally in masquerades. CONCLUSIONS The 3ST pattern characteristic of unilateral SO palsy may be mimicked in all respects by masquerades.
Collapse
Affiliation(s)
- Joseph L Demer
- From the Department of Ophthalmology (J.L.D., R.A.C.), University of California Los Angeles, Los Angeles, California, USA; Stein Eye Institute (J.L.D.), University of California Los Angeles, Los Angeles, California, USA; Bioengineering Department (J.L.D.), University of California Los Angeles, Los Angeles, California, USA; Department of Neurology (J.L.D.), University of California Los Angeles, Los Angeles, California, USA.
| | - Robert A Clark
- From the Department of Ophthalmology (J.L.D., R.A.C.), University of California Los Angeles, Los Angeles, California, USA
| |
Collapse
|
3
|
Wang Z, Fu L, Shen T, Qiu X, Yu X, Shen H, Yan J. Supramaximal Horizontal Rectus Recession-Resection Surgery for Complete Unilateral Abducens Nerve Palsy. Front Med (Lausanne) 2022; 8:795665. [PMID: 35273968 PMCID: PMC8901715 DOI: 10.3389/fmed.2021.795665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/27/2021] [Indexed: 11/30/2022] Open
Abstract
Purpose To review the surgical procedures and outcomes of supramaximal horizontal rectus recession–resection surgery for abduction deficiency and esotropia resulting from complete unilateral abducens nerve palsy. Methods A total of 36 consecutive cases diagnosed as complete abducens nerve palsy, receiving supramaximal medial rectus recession (8.5 ± 1.4 mm, range: 6–10) combined with a supramaximal lateral rectus resection (11.1 ± 1.7 mm, range: 8–14) as performed over the period from 2017 to 2020, were reviewed retrospectively. All surgeries were performed by a single surgeon. Pre- and post-operative ocular motility, ocular alignment, forced duction test, binocular vision, abnormal head posture, and surgical complications were assessed. Results Of these 36 cases, 23 (63.8%) were followed up for greater than 2 months (Mean ± SD = 8.4 ± 6.0, range: 2–24) after surgery and the collected data was presented. Mean ± SD age of these patients was 41.7 ± 14.4 (range: 12–67) years with 73.9% being female. Trauma (52.2%, 12/23) and cerebral lesions (21.7%, 5/23) were the primary etiologies for this condition. Esodeviation in primary position improved from 55.5 ± 27.2 prism diopters (PD) (range: +25 to +123) to 0.04 ± 7.3 PD (range: −18 to +12) as assessed on their last visit. Pre-operative abduction deficits of −5.6 ± 1.0 (range: −8 to −4) reduced to −2.4 ± 1.4 (range: −4 to 0) post-operatively. The mean dose-effect coefficient of 2.80 ± 1.20 PD/mm (range: 1.07–6.05) was positively correlated with pre-operative esodeviation. Rates of overcorrection and ortho were 69.6 and 26.1%, respectively, on the first day after surgery, while on their last visit the respective levels were 4.3 and 82.6%. Conclusion Supramaximal horizontal rectus recession–resection surgery is an effective treatment method for complete abduction deficiency. The dose-effect was positively correlated with pre-operative esodeviation. Overcorrection on the first day post-operatively is required for a long-term satisfactory surgical outcome.
Collapse
Affiliation(s)
- Zhonghao Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Licheng Fu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Tao Shen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xuan Qiu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xinping Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Huangxuan Shen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jianhua Yan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| |
Collapse
|
4
|
Falcone MM, Rong AJ, Salazar H, Redick DW, Falcone S, Cavuoto KM. Acute abducens nerve palsy in a patient with the novel coronavirus disease (COVID-19). J AAPOS 2020; 24:216-217. [PMID: 32592761 PMCID: PMC7311910 DOI: 10.1016/j.jaapos.2020.06.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 11/25/2022]
Abstract
We present a case of an abducens nerve palsy in a previously healthy young man in the setting of SARS-CoV-2 infection. Magnetic resonance imaging obtained 5 weeks after the onset of diplopia demonstrated an atrophic left lateral rectus muscle, which was hyperintense on T2 weighting, consistent with denervation. Although the mechanism of the nerve palsy remains unclear, it is suspected to be related to his viral illness, because the patient had no preexisting vascular risk factors or evidence of other neurologic disease on neuroimaging. Cranial nerve palsies may represent part of the neurologic spectrum of COVID-19.
Collapse
Affiliation(s)
- Michelle M Falcone
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Andrew J Rong
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Humberto Salazar
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - D Wade Redick
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Steven Falcone
- Department of Radiology, University of Miami Miller School of Medicine, Miami, Florida
| | - Kara M Cavuoto
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida.
| |
Collapse
|
5
|
Abstract
Recent reports confirm innervational compartments of select rectus extraocular muscles as well as the superior oblique.1 Histopathological and orbital imaging studies demonstrate well defined compartmental innervation of the horizontal rectus muscles with less differentiation in the vertical rectus muscles. Acquired vertical misalignment not associated with cyclovertical muscle dysfunction has been associated with horizontal rectus muscle compartment dysfunction. Pattern and other forms of strabismus have been associated with segmental or compartmental abnormal innervation of the extraocular muscles. Taking advantage of segmental function and innervation, selective weakening and strengthening procedures have been used to treat patients with incomitant near/distance disparities, incomitant vertical and torsional strabismus, and patients with A- and V-pattern strabismus.
Collapse
Affiliation(s)
- Stacy L Pineles
- Stein Eye Institute, University of California Los Angeles , Los Angeles, California.,Department of Ophthalmology, University of California Los Angeles , Los Angeles, California
| | - Melinda Y Chang
- Department of Ophthalmology, Vison Center at Children's Hospital Los Angeles , Los Angeles, California.,Roski Eye Institute, University of Southern California , Los Angeles, California
| | - Federico G Velez
- Duke Eye Center, Duke University , Durham, North Carolina.,Doheny Eye Institute, University of California Los Angeles , Los Angeles, California
| |
Collapse
|
6
|
Affiliation(s)
- Joel M. Miller
- Eidactics and The Strabismus Research Foundation, San Francisco, California, United States
| |
Collapse
|
7
|
Demer JL, Clark RA. Translation and eccentric rotation in ocular motor modeling. PROGRESS IN BRAIN RESEARCH 2019; 248:117-126. [PMID: 31239125 DOI: 10.1016/bs.pbr.2019.04.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Current models of ocular mechanics do not fully account for potentially large globe translations associated with eye rotation. Such combined motion can be measured using magnetic resonance imaging in axial planes. We imaged orbits of normal volunteers fixating horizontally eccentric targets. These data indicate that the human eye acts as if it rotates eccentrically about a varying point typically anterior to the geometric globe center, but significantly lateral in abduction and medial in adduction. Assumed eccentricity of the ocular rotational center would vary the torque lever arms for the horizontal rectus muscles, with an appreciably smaller relative lever arm for the medial rectus muscle in adduction than would be the case for oculocentric rotation. Such variation in ocular rotational center might alter muscle torque without commensurate change in muscle tension, as appears to happen in convergence.
Collapse
Affiliation(s)
- Joseph L Demer
- Stein Eye Institute and Departments of Ophthalmology and Neurology, University of California, Los Angeles, CA, United States.
| | - Robert A Clark
- Stein Eye Institute and Departments of Ophthalmology and Neurology, University of California, Los Angeles, CA, United States
| |
Collapse
|
8
|
Demer JL, Clark RA. Functional anatomy of extraocular muscles during human vergence compensation of horizontal heterophoria. J Neurophysiol 2019; 122:105-117. [PMID: 31042451 DOI: 10.1152/jn.00152.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We employed magnetic resonance imaging to quantify human extraocular muscle (EOM) contractility during intermittent convergent and divergent strabismus with each eye viewing monocularly at 20 cm compared with centered target fusion. Contractility, indicated by posterior partial volume change, was analyzed in transverse rectus and in medial and lateral superior oblique (SO) muscle compartments. In five subjects with intermittent esotropia, abduction of the deviated eye to monocular target fixation was associated with significant whole lateral rectus (LR) contraction, but with medial rectus (MR) relaxation that was significantly greater in the superior than inferior compartment. Esotropic eye abduction to binocular fusion was associated with similar relaxation in the two MR compartments, but with greater contraction in the LR's superior than inferior compartment. The whole diverging eye SO muscle relaxed. In three subjects with intermittent exotropia, converging eye fusional adduction was associated with significant whole LR relaxation and with MR contraction attributable to significantly greater contraction in the superior than inferior compartment. In adduction of the exotropic eye to monocular target fixation but not fusional adduction, the whole SO exhibited significant relaxation. Rectus pulley positions were not significantly altered by fusion of either form of intermittent strabismus. Globe rotational axis was eccentric in intermittent strabismus, rolling the eye so that rectus EOM lever arms facilitated vergence. These results confirm, and extend to fusion of intermittent horizontal strabismus, differential compartmental function in horizontal rectus EOMs and suggest a novel role for the SO in compensation of both intermittent esotropia and exotropia. NEW & NOTEWORTHY Disjunctive eye movements normally permit binocular fixation in near visual space but also compensate for mechanical imbalances in binocular alignment developing over the life span. Magnetic resonance imaging of the extraocular muscles demonstrates important differential function in muscle compartments during compensation of large-angle intermittent convergent and divergent strabismus in humans. Eye translation during rotation also enhances vergence compensation of intermittent strabismus.
Collapse
Affiliation(s)
- Joseph L Demer
- Department of Ophthalmology, David Geffen Medical School, University of California , Los Angeles, California.,Department of Neurology, David Geffen Medical School, University of California , Los Angeles, California
| | - Robert A Clark
- Department of Ophthalmology, David Geffen Medical School, University of California , Los Angeles, California
| |
Collapse
|
9
|
Shin HJ, Lee SH, Ha TJ, Song WC, Koh KS. Intramuscular Nerve Distribution in the Medial Rectus Muscle and Its Clinical Implications. Curr Eye Res 2019; 44:522-526. [PMID: 30624996 DOI: 10.1080/02713683.2018.1562556] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PURPOSE The intramuscular nerve distribution in the extraocular muscles may be crucial for understanding their physiological and pathological responses. This study aimed to determine the oculomotor nerve distribution in the medial rectus muscle (MR) using Sihler's staining. METHOD Thirty-seven MRs from 23 cadavers were investigated. The MR including the oculomotor nerve was finely dissected from its origin to its insertion point into the sclera. The total length of the muscle-belly, tendon length and maximum width of the muscle were measured. We evaluated the pattern of distribution and the length of the intramuscular nerve distribution by gross observation after performing Sihler's staining, which is a method for visualizing the distribution of nerve fibers without alteration of the nerve. RESULTS The total length of the muscle-belly, tendon length, and muscle width were 37.6 ± 4.6 mm, 4.4 ± 1.9 mm, and 10 ± 1.8 mm, respectively. The oculomotor nerve enters the MR at a mean of two-fifths along the muscle (24 ± 2.0 mm posterior to the insertion point) and then typically divides into a few branches (mean of 2.1). The intramuscular nerve distribution showed a Y-shaped ramification, forming the terminal nerve plexus, and its course typically finished at around 17 ± 1.5 mm posterior to the muscle insertion point by gross observation. The nerve plexus in the upper part generally coursed more distally than the lower part. CONCLUSION This new information regarding the nerve distribution pattern of MR will be helpful for understanding MR function and the diverse pathophysiology of strabismus.
Collapse
Affiliation(s)
- Hyun Jin Shin
- a Department of Ophthalmology , Konkuk University Medical Center, Konkuk University School of Medicine , Seoul , Republic of Korea
| | - Shin-Hyo Lee
- b Department of Anatomy, Research Institute of Medical Science , Konkuk University School of Medicine , Seoul , Republic of Korea
| | - Tae-Jun Ha
- b Department of Anatomy, Research Institute of Medical Science , Konkuk University School of Medicine , Seoul , Republic of Korea
| | - Wu-Chul Song
- b Department of Anatomy, Research Institute of Medical Science , Konkuk University School of Medicine , Seoul , Republic of Korea
| | - Ki-Seok Koh
- b Department of Anatomy, Research Institute of Medical Science , Konkuk University School of Medicine , Seoul , Republic of Korea
| |
Collapse
|
10
|
Clark RA, Demer JL. Magnetic Resonance Imaging of the Globe-Tendon Interface for Extraocular Muscles: Is There an "Arc of Contact"? Am J Ophthalmol 2018; 194:170-181. [PMID: 30030978 PMCID: PMC6420818 DOI: 10.1016/j.ajo.2018.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/09/2018] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine if the "arc of contact" is an accurate approximation of the globe-tendon interface for the biomechanical modeling of extraocular muscle (EOM) force transfer onto the globe. METHODS At a single academic institution, 18 normal and 14 strabismic subjects were prospectively recruited for surface-coil enhanced magnetic resonance imaging at 312- or 390-μm resolution in axial planes for horizontal EOMs (23 subjects, 26 orbits) and sagittal planes for vertical EOMs (13 subjects, 22 orbits) during large ipsiversive ductions. The measured angle at insertion and the predicted angle assuming an "arc of contact" were compared using paired t tests. RESULTS For normal EOMs, the measured angle at insertion was significantly greater than predicted assuming an "arc of contact" for the medial rectus (MR) (5.0 ± 4.8 degrees vs 0.0 ± 0.0 degrees, P = .03), lateral rectus (LR) (4.9 ± 3.0 degrees vs 0.0 ± 0.0 degrees, P = .02), inferior rectus (7.4 ± 4.8 degrees vs 1.2 ± 2.6 degrees, P = .00003), and superior rectus (0.6 ± 1.1 degrees vs 0.0 ± 0.0 degrees, P = .04). In strabismic subjects, the measured angle was significantly greater for the MR in abducens palsy (9.9 ± 4.3 degrees vs 0.5 ± 0.7 degrees, P = .0007) and after MR resection (9.0 ± 6.9 degrees vs 1.2 ± 2.4 degrees, P = .02), but not after LR recession (2.9 vs 0.0 degrees). Single subjects had comparable angles after MR recession, but markedly different angles after MR and LR posterior fixation. CONCLUSIONS Contrary to the "arc of contact" biomechanical model, normal and postsurgical EOMs are significantly non-tangent to the globe at their scleral insertions. The "arc of contact" should be replaced in biomechanical modeling by the experimentally measured angles at tendon insertions. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
Collapse
Affiliation(s)
- Robert A Clark
- Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, Los Angeles, California, USA.
| | - Joseph L Demer
- Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, Los Angeles, California, USA; Department of Neurology, David Geffen Medical School, University of California, Los Angeles, Los Angeles, California, USA; Department of Neuroscience, David Geffen Medical School, University of California, Los Angeles, Los Angeles, California, USA; Biomedical Engineering Interdepartmental Programs, David Geffen Medical School, University of California, Los Angeles, Los Angeles, California, USA
| |
Collapse
|
11
|
Abstract
Normal orbital anatomy plays a foundational role in stabilizing binocular eye movements. Abnormal orbital anatomy, contrariwise, destabilizes binocular eye alignment by introducing eccentric and unbalanced EOM forces. These abnormalities can be categorized into five broad etiologies: (1) orbital structural disorders; (2) globe size disorders; (3) degenerative disorders; (4) innervational disorders; and (5) trauma. Orbital imaging provides important diagnostic information on EOM path and innervational status, but only if performed properly. The three critical elements are (1) maximize the field of view by focusing on the orbit of interest; (2) control gaze, ideally imaging in primary position; and (3) image perpendicular (direct coronals) and parallel (axial for horizontal, sagittal for vertical) to the EOM(s) of interest. Images should be analyzed systematically by comparing EOM size and location between orbits and with established normative values. The single most critical image is the most anterior direct coronal plane that contains both globe and clearly defined EOM cross sections. EOM positional abnormalities in this plane establish the diagnosis for the first three categories of orbital abnormalities. Innervational abnormalities are best evaluated in the mid-orbit; asymmetry in mid-orbital EOM size and shape defines or confirms innervational disorders like complete or partial cranial nerve palsies.
Collapse
|
12
|
Intramuscular Distribution of the Abducens Nerve in the Lateral Rectus Muscle for the Management of Strabismus. Curr Eye Res 2018; 43:689-695. [PMID: 29447480 DOI: 10.1080/02713683.2018.1438631] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
AIMS To elucidate the intramuscular distribution and branching patterns of the abducens nerve in the lateral rectus (LR) muscle so as to provide anatomical confirmation of the presence of compartmentalization, including for use in clinical applications such as botulinum toxin injections. METHODS Thirty whole-mount human cadaver specimens were dissected and then Sihler's stain was applied. The basic dimensions of the LR and its intramuscular nerve distribution were investigated. The distances from the muscle insertion to the point at which the abducens nerve enters the LR and to the terminal nerve plexus were also measured. RESULTS The LR was 46.0 mm long. The abducens nerve enters the muscle on the posterior one-third of the LR and then typically divides into a few branches (average of 1.8). This supports a segregated abducens nerve selectively innervating compartments of the LR. The intramuscular nerve distribution showed a Y-shaped ramification with root-like arborization. The intramuscular nerve course finished around the middle of the LR (24.8 mm posterior to the insertion point) to form the terminal nerve plexus. This region should be considered the optimal target site for botulinum toxin injections. We have also identified the presence of an overlapping zone and communicating nerve branches between the neighboring LR compartments. CONCLUSION Sihler's staining is a useful technique for visualizing the entire nerve network of the LR. Improving the knowledge of the nerve distribution patterns is important not only for researchers but also clinicians to understand the functions of the LR and the diverse pathophysiology of strabismus.
Collapse
|
13
|
Wang JMH, Edwards BA, Loukas M, Oskouian RJ, Tubbs RS. Supernumerary Abducens Nerves: A Comprehensive Review. World Neurosurg 2017; 112:39-45. [PMID: 29158094 DOI: 10.1016/j.wneu.2017.11.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 11/07/2017] [Accepted: 11/09/2017] [Indexed: 11/17/2022]
Abstract
BACKGROUND Branching and/or replication of the abducens nerve is not an uncommon occurrence. Although numerous variations have been documented, the rarest forms are duplicated or triplicated nerves, where multiple nerve roots originate from the brainstem, travel intracranially, and attach to the lateral rectus as separate entities. METHODS We conducted a systematic literature search on the topic of supernumerary abducens nerve, using PubMed and Google Scholar. RESULTS After screening, 16 studies were included: 11 cadaveric studies and 6 case reports. CONCLUSIONS In this paper, we review the literature on variations found, discuss current hypotheses and clinical relevance, and propose future studies. Neurosurgeons should be aware of such nerve variants when viewing imaging or operating in the regions traversed by the abducens nerve.
Collapse
Affiliation(s)
- Joy M H Wang
- Department of Anatomical Sciences, St. George's University, Grenada, West Indies.
| | - Bryan Adam Edwards
- Department of Anatomical Sciences, St. George's University, Grenada, West Indies
| | - Marios Loukas
- Department of Anatomical Sciences, St. George's University, Grenada, West Indies
| | | | - R Shane Tubbs
- Seattle Science Foundation, Seattle, Washington, USA
| |
Collapse
|
14
|
Abstract
PURPOSE OF REVIEW To review the most recent literature regarding the clinical experience of imaging modalities in strabismus. RECENT FINDINGS MRI of extraocular muscles (EOMs) has elucidated the roles of variation in compartmental contraction of EOMs and further evidence of EOM pulley heterotopy in various strabismus patterns, which may contribute to the clinical and surgical management of patients as this mode of imaging becomes more readily available. Ultrasound biomicroscopy (UBM) and anterior-segment optical coherence tomography (AS-OCT) may play a role in determining the location of EOMs which could also aid in devising a preoperative surgical plan, especially in those who have had prior strabismus surgery. SUMMARY Although MRI, UBM, and AS-OCT show promise in the formulation of a treatment plan in complex strabismus, more research regarding the role and limitations of these imaging modalities is required before they become the mainstay of strabismus evaluation.
Collapse
|
15
|
Nam YS, Kim IB, Shin SY. Detailed anatomy of the abducens nerve in the lateral rectus muscle. Clin Anat 2017; 30:873-877. [PMID: 28514515 DOI: 10.1002/ca.22918] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 04/25/2017] [Accepted: 04/27/2017] [Indexed: 11/10/2022]
Abstract
The aims of this study were to elucidate the detailed anatomy of the abducens nerve in the lateral rectus muscle (LRM) and the intramuscular innervation pattern using Sihler staining. In this cohort study, 32 eyes of 16 cadavers were assessed. Dissection was performed from the LRM origin to its insertion. The following distances were measured: from LRM insertion to the bifurcation point of the abducens nerve, from LRM insertion to the entry site of the superior branch or inferior branch, from the upper border of the LRM to the entry site of the superior branch, from the lower border of LRM to the entry site of inferior branch, and the widths of the main trunk and superior and inferior branches. The single trunk of the abducens nerve divided into two branches 37 mm from insertion of the LRM, and 22 of 32 (68.8%) orbits showed only two superior and inferior branches with no subdivision. The superior branch entered the LRM more anteriorly (P = 0.037) and the superior branch was thinner than the inferior branch (P = 0.040). The most distally located intramuscular nerve ending was observed at 52.9 ± 3.5% of the length of each muscle. Non-overlap between the superior and inferior intramuscular arborization of the nerve was detected in 27 of 32 cases (84.4%). Five cases (15.6%) showed definite overlap of the superior and inferior zones. This study revealed the detailed anatomy of the abducens nerve in the LRM and provides helpful information to understand abducens nerve palsy. Clin. Anat. 30:873-877, 2017. © 2017 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Yong Seok Nam
- Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - In-Beom Kim
- Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sun Young Shin
- Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea
| |
Collapse
|
16
|
Patel VA, Zacharia TT, Goldenberg D, McGinn JD. End-organ radiographic manifestations of cranial neuropathies: A concise review. Clin Imaging 2017; 44:5-11. [PMID: 28364580 DOI: 10.1016/j.clinimag.2017.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 02/02/2017] [Accepted: 03/22/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cranial neuropathies are a spectrum of disorders associated with dysfunction of one or more of the twelve cranial nerves and the subsequent anatomic structures they innervate. OBJECTIVE The purpose of this article is to review radiographic imaging findings of end-organ aberrations secondary to cranial neuropathies. METHOD All articles related to cranial neuropathies were retrieved through the PubMed MEDLINE NCBI database from January 1, 1991 to August 31, 2014. These manuscripts were analyzed for their relation to cranial nerve end-organ disease pathogenesis and radiographic imaging. RESULTS The present review reveals detectable end-organ changes on CT and/or MRI for the following cranial nerves: olfactory nerve, optic nerve, oculomotor nerve, trochlear nerve, trigeminal nerve, abducens nerve, facial nerve, vestibulocochlear nerve, glossopharyngeal nerve, vagus nerve, accessory nerve, and hypoglossal nerve. CONCLUSION Radiographic imaging can assist in the detailed evaluation of end-organ involvement, often revealing a corresponding cranial nerve injury with high sensitivity and diagnostic accuracy. A thorough understanding of the distal manifestations of cranial nerve disease can optimize early pathologic detection as well as dictate further clinical management.
Collapse
Affiliation(s)
- Vijay A Patel
- Department of Surgery, Division of Otolaryngology - Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, PA, USA
| | - Thomas T Zacharia
- Department of Radiology, The Pennsylvania State University, College of Medicine, Hershey, PA, USA
| | - David Goldenberg
- Department of Surgery, Division of Otolaryngology - Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, PA, USA
| | - Johnathan D McGinn
- Department of Surgery, Division of Otolaryngology - Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, PA, USA.
| |
Collapse
|
17
|
Suh SY, Clark RA, Le A, Demer JL. Extraocular Muscle Compartments in Superior Oblique Palsy. Invest Ophthalmol Vis Sci 2016; 57:5535-5540. [PMID: 27768791 PMCID: PMC5080936 DOI: 10.1167/iovs.16-20172] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Purpose To investigate changes in volumes of extraocular muscle (EOM) compartments in unilateral superior oblique (SO) palsy using magnetic resonance imaging (MRI). Methods High-resolution, surface-coil MRI was obtained in 19 patients with unilateral SO palsy and 19 age-matched orthotropic control subjects. Rectus EOMs and the SO were divided into two anatomic compartments for volume analysis in patients with unilateral SO palsy, allowing comparison of total compartmental volumes versus controls. Medial and lateral compartmental volumes of the SO muscle were compared in patients with isotropic (round shape) versus anisotropic (elongated shape) SO atrophy. Results The medial and lateral compartments of the ipsilesional SO muscles were equally atrophic in isotropic SO palsy, whereas the lateral compartment was significantly smaller than the medial in anisotropic SO palsy (P = 0.01). In contrast to the SO, there were no differential compartmental volume changes in rectus EOMs; however, there was significant total muscle hypertrophy in the ipsilesional inferior rectus (IR) and lateral rectus (LR) muscles and contralesional superior rectus (SR) muscles. Medial rectus (MR) volume was normal both ipsi- and contralesionally. Conclusions A subset of patients with SO palsy exhibit selective atrophy of the lateral, predominantly vertically acting SO compartment. Superior oblique atrophy is associated with whole-muscle volume changes in the ipsilesional IR, ipsilesional LR, and contralesional SR; however, SO muscle atrophy is not associated with compartmentally selective volume changes in the rectus EOMs. Selective compartmental SO pathology may provide an anatomic mechanism that explains some of the variability in clinical presentations of SO palsy.
Collapse
Affiliation(s)
- Soh Youn Suh
- Department of Ophthalmology, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California
| | - Robert A Clark
- Department of Ophthalmology, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 2David Geffen Medical School at University of California, Los Angeles, Los Angeles, California
| | - Alan Le
- Department of Ophthalmology, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 3Neuroscience Interdepartmental Program, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 4Bioengineering Interdepartmental Program, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California
| | - Joseph L Demer
- Department of Ophthalmology, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 2David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 3Neuroscience Interdepartmental Program, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 4Bioengineering Interdepartmental Program, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 5Stein Eye Institute, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California 6Department of Neurology, David Geffen Medical School at University of California, Los Angeles, Los Angeles, California
| |
Collapse
|
18
|
Demer JL. Optic Nerve Sheath as a Novel Mechanical Load on the Globe in Ocular Duction. Invest Ophthalmol Vis Sci 2016; 57:1826-38. [PMID: 27082297 PMCID: PMC4849549 DOI: 10.1167/iovs.15-18718] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Purpose The optic nerve (ON) sheath's role in limiting duction has been previously unappreciated. This study employed magnetic resonance imaging (MRI) to demonstrate this constraint on adduction. Methods High-resolution, surface coil axial MRI was obtained in 11 normal adults, 14 subjects with esotropia (ET) having normal axial length (AL) < 25.8 mm, 13 myopic subjects with ET and mean AL 29.3 ± 3.3 (SD) mm, and 7 subjects with exotropia (XT). Gaze angles and ON lengths were measured for scans employing eccentric lateral fixation in which an ON became completely straightened. Results In all groups, ON straightening occurred only in the adducting, not abducting, eye. Adduction at ON straightening was 26.0 ± 8.8° in normal subjects, not significantly different from XT at 22.2 ± 11.8°. However, there was significant increase in comparable adduction in ET to 36.3 ± 9.3°, and in myopic ET to 33.6 ± 10.7° (P < 0.04). Optic nerve length at straightening was 27.6 ± 2.7 mm in normals, not significantly different from 28.2 ± 2.8 mm in ET and 27.8 ± 2.7 mm in XT. In myopic ET, ON length at straightening was significantly reduced to 24.0 ± 2.9 mm (P < 0.002) and was associated with globe retraction in adduction, suggesting ON tethering. Conclusions Large adduction may exhaust length redundancy in the normally sinuous ON and sheath, so that additional adduction must stretch the sheath and retract or deform the globe. These mechanical effects are most significant in ET with axial myopia, but may also exert traction on the posterior sclera absent strabismus or myopia. Tethering by the ON sheath in adduction is an important, novel mechanical load on the globe.
Collapse
|
19
|
Yulek F, Demer JL. Isolated schwannoma involving extraocular muscles. J AAPOS 2016; 20:343-7. [PMID: 27424045 PMCID: PMC5003769 DOI: 10.1016/j.jaapos.2016.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/14/2016] [Accepted: 05/27/2016] [Indexed: 11/25/2022]
Abstract
BACKGROUND Progressive strabismus initially considered idiopathic may be caused by isolated schwannomas of motor nerves to extraocular muscles, detectable only on careful imaging. This study reviewed clinical experience of a referral practice in identifying schwannomas on magnetic resonance imaging (MRI). METHODS We reviewed 647 cases imaged for strabismus to identify presumed cranial nerve schwannomas, identified by gadodiamide-enhanced, high-resolution surface coil orbital MRI and thin-section cranial MRI. Clinical features and management were correlated with MRI. RESULTS Schwannomas were identified as fusiform intraneural enlargements in 8 cases: 1 affecting the trochlear nerve; 2, the abducens nerve; and 5 the oculomotor nerve. Involved muscles were atrophic. Both abducens schwannomas, 1 superior oblique, and 1 oculomotor schwannoma were subarachnoid; 3 were intraorbital, and bilateral oculomotor lesions of 1 case extended from cavernous sinus to orbit. Associated strabismus progressed for 3-17 years. Abducens schwannoma caused esotropia; trochlear schwannoma caused hypertropia and cyclotropia. Intracranial oculomotor schwannoma caused mydriasis and exotropia. Intraorbital schwannoma caused exotropia with or without hypertropia. Since lesion diameters were 3-9 mm, 6 had been previously missed on routine MRI. CONCLUSIONS Progressive, acquired strabismus may be caused by isolated cranial nerve schwannomas, representing about 1% of strabismus cases in this study, involving the oculomotor more than abducens nerve. Because most schwannomas are small and deep in the orbit, findings could be readily missed by routine imaging, leading to a possible diagnosis of idiopathic strabismus. Schwannomas should be suspected when extraocular muscles are atrophic, but the causative lesions themselves are identifiable only using targeted, high resolution MRI.
Collapse
Affiliation(s)
- Fatma Yulek
- Department of Ophthalmology, Stein Eye Institute, UCLA, Los Angeles, California
| | - Joseph L Demer
- Department of Ophthalmology, Stein Eye Institute, UCLA, Los Angeles, California; Department of Neurology, Neuroscience Interdepartmental Program, Bioengineering Interdepartmental Program, UCLA, Los Angeles, California.
| |
Collapse
|
20
|
Abstract
BACKGROUND Strabismus is commonly encountered in neuro-ophthalmology practice. Adult patients may present with symptoms including disabling diplopia and decreased quality of life. Although presentation to the neuro-ophthalmologist often prompts a thorough workup for a neurologic basis of ocular misalignment, advances in orbital imaging and understanding of orbital mechanics have revealed novel mechanical causes. A goal of this review is to clarify mechanical mechanisms of strabismus that were formerly assumed be neurologic in origin. EVIDENCE ACQUISITION The authors combine their own research and clinical experience with a literature review using PubMed. RESULTS Aberrant paths of the extraocular muscles can lead to strabismus. The extraocular muscles have connective tissue pulleys that control muscle paths and are, in turn, influenced by the extraocular muscle orbital layers. Orbital connective tissues, including the pulleys, constrain extraocular muscle paths. Abnormalities of these tissues may lead to strabismus that is not due to neurologic pathology. Some extraocular muscles are divided into independent neuromuscular compartments, so that partial motor nerve lesions may manifest as selective denervation of only 1 compartment, complicating the presentation of neuropathic strabismus. CONCLUSIONS Strabismus in adults due to nonneurologic causes can result from recently described abnormalities of the orbital connective tissue pulley system. Advances in understanding of compartmental extraocular muscle anatomy and innervation can explain cyclovertical strabismus in partial nerve palsies. Recognition of the underlying pathogenesis of the strabismus can lead to improved treatments.
Collapse
|
21
|
Clark RA, Demer JL. Functional morphometry demonstrates extraocular muscle compartmental contraction during vertical gaze changes. J Neurophysiol 2015; 115:370-8. [PMID: 26538608 DOI: 10.1152/jn.00825.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/02/2015] [Indexed: 01/08/2023] Open
Abstract
Anatomical studies demonstrate selective compartmental innervation of most human extraocular muscles (EOMs), suggesting the potential for differential compartmental control. This was supported by magnetic resonance imaging (MRI) demonstrating differential lateral rectus (LR) compartmental contraction during ocular counterrolling, differential medial rectus (MR) compartmental contraction during asymmetric convergence, and differential LR, inferior rectus (IR), and superior oblique (SO) compartmental contraction during vertical vergence. To ascertain possible differential compartmental EOM contraction during vertical ductions, surface coil MRI was performed over a range of target-controlled vertical gaze positions in 25 orbits of 13 normal volunteers. Cross-sectional areas and partial volumes of EOMs were analyzed in contiguous, quasi-coronal 2-mm image planes spanning origins to globe equator to determine morphometric features correlating best with contractility. Confirming and extending prior findings for horizontal EOMs during horizontal ductions, the percent change in posterior partial volume (PPV) of vertical EOMs from 8 to 14 mm posterior to the globe correlated best with vertical duction. EOMs were then divided into equal transverse compartments to evaluate the effect of vertical gaze on changes in PPV. Differential contractile changes were detected in the two compartments of the same EOM during infraduction for the IR medial vs. lateral (+4.4%, P = 0.03), LR inferior vs. superior (+4.0%, P = 0.0002), MR superior vs. inferior (-6.0%, P = 0.001), and SO lateral vs. medial (+9.7%, P = 0.007) compartments, with no differential contractile changes in the superior rectus. These findings suggest that differential compartmental activity occurs during normal vertical ductions. Thus all EOMs may contribute to cyclovertical actions.
Collapse
Affiliation(s)
- Robert A Clark
- Stein Eye Institute and Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and
| | - Joseph L Demer
- Stein Eye Institute and Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and Department of Neurology, David Geffen Medical School, University of California, Los Angeles, California
| |
Collapse
|
22
|
Bhambhwani V, Pandey PK, Kadav M, C A. Superior Oblique Extraocular Muscle Shape in Superior Oblique Palsy. Am J Ophthalmol 2015; 160:846-7. [PMID: 26251124 DOI: 10.1016/j.ajo.2015.07.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 07/14/2015] [Indexed: 10/23/2022]
|
23
|
Chang MY, Pineles SL, Velez FG. Adjustable small-incision selective tenotomy and plication for correction of incomitant vertical strabismus and torsion. J AAPOS 2015; 19:410-6. [PMID: 26486021 PMCID: PMC4637275 DOI: 10.1016/j.jaapos.2015.07.290] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/23/2015] [Accepted: 07/28/2015] [Indexed: 11/16/2022]
Abstract
PURPOSE To evaluate the effectiveness of adjustable small-incision selective tenotomy and plication of vertical rectus muscles in correcting vertical strabismus incomitant in horizontal gaze positions and cyclotorsion. METHODS The medical records of all patients who underwent adjustable small-incision selective tenotomy or plication of a vertical rectus muscle for correction of horizontally incomitant vertical strabismus or cyclotorsion by a single surgeon at a single eye institute from July 2013 to September 2014 were retrospectively reviewed. Selective tenotomy and plication were performed on either the nasal or temporal side of vertical rectus muscles, based on the direction of cyclotorsion and incomitance of vertical strabismus. RESULTS Of 9 patients identified, 8 (89%) had successful correction of horizontally incomitant vertical strabismus, with postoperative vertical alignment within 4(Δ) of orthotropia in primary position, lateral gazes, and downgaze. Of the 8 patients with preoperative cyclotorsion, 4 (50%) were successfully corrected, with <5° of cyclotorsion postoperatively. Of the 4 patients in whom cyclotorsion did not improve, 3 had undergone prior strabismus surgery, and 2 had restrictive strabismus. Eight of the 9 patients (89%) reported postoperative resolution of diplopia. CONCLUSIONS Adjustable small-incision selective tenotomy and plication effectively treat horizontally incomitant vertical strabismus. These surgeries may be less effective for correcting cyclotorsion in patients with restriction or prior strabismus surgery. Advantages are that they may be performed in an adjustable manner and, in some cases, under topical anesthesia.
Collapse
Affiliation(s)
- Melinda Y Chang
- The Stein Eye Institute, University of California-Los Angeles, California
| | - Stacy L Pineles
- The Stein Eye Institute, University of California-Los Angeles, California
| | - Federico G Velez
- The Stein Eye Institute, University of California-Los Angeles, California; Doheny Eye Institute, University of California-Los Angeles, California; Olive View UCLA Medical Center, Sylmar, California.
| |
Collapse
|
24
|
Le A, Poukens V, Ying H, Rootman D, Goldberg RA, Demer JL. Compartmental Innervation of the Superior Oblique Muscle in Mammals. Invest Ophthalmol Vis Sci 2015; 56:6237-46. [PMID: 26426404 PMCID: PMC4594531 DOI: 10.1167/iovs.15-17602] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 08/21/2015] [Indexed: 01/13/2023] Open
Abstract
PURPOSE Intramuscular innervation of mammalian horizontal rectus extraocular muscles (EOMs) is compartmental. We sought evidence of similar compartmental innervation of the superior oblique (SO) muscle. METHODS Three fresh bovine orbits and one human orbit were dissected to trace continuity of SO muscle and tendon fibers to the scleral insertions. Whole orbits were also obtained from four humans (two adults, a 17-month-old child, and a 33-week stillborn fetus), two rhesus monkeys, one rabbit, and one cow. Orbits were formalin fixed, embedded whole in paraffin, serially sectioned in the coronal plane at 10-μm thickness, and stained with Masson trichrome. Extraocular muscle fibers and branches of the trochlear nerve (CN4) were traced in serial sections and reconstructed in three dimensions. RESULTS In the human, the lateral SO belly is in continuity with tendon fibers inserting more posteriorly on the sclera for infraducting mechanical advantage, while the medial belly is continuous with anteriorly inserting fibers having mechanical advantage for incycloduction. Fibers in the monkey superior SO insert more posteriorly on the sclera to favor infraduction, while the inferior portion inserts more anteriorly to favor incycloduction. In all species, CN4 bifurcates prior to penetrating the SO belly. Each branch innervates a nonoverlapping compartment of EOM fibers, consisting of medial and lateral compartments in humans and monkeys, and superior and inferior compartments in cows and rabbits. CONCLUSIONS The SO muscle of humans and other mammals is compartmentally innervated in a manner that could permit separate CN4 branches to selectively influence vertical versus torsional action.
Collapse
Affiliation(s)
- Alan Le
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, California, United States
- Biomedical Engineering Interdepartmental Program, University of California, Los Angeles, California, United States
| | - Vadims Poukens
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, California, United States
| | - Howard Ying
- Department of Ophthalmology, Johns Hopkins University, Baltimore, Maryland, United States
| | - Daniel Rootman
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, California, United States
| | - Robert A. Goldberg
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, California, United States
| | - Joseph L. Demer
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, California, United States
- Biomedical Engineering Interdepartmental Program, University of California, Los Angeles, California, United States
- Neuroscience Interdepartmental Program, University of California, Los Angeles, California, United States
- Department of Neurology, University of California, Los Angeles, California, United States
| |
Collapse
|
25
|
Pandey PK, Bhambhwani V, Thirumalai S, Ranjith PC, Gupta P. Lateral Rectus Superior Compartment Palsy. Am J Ophthalmol 2015; 160:205-6. [PMID: 26054471 DOI: 10.1016/j.ajo.2015.03.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 03/25/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
|
26
|
Shin SY, Demer JL. Superior oblique extraocular muscle shape in superior oblique palsy. Am J Ophthalmol 2015; 159:1169-1179.e2. [PMID: 25747676 DOI: 10.1016/j.ajo.2015.02.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Revised: 02/24/2015] [Accepted: 02/25/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE To investigate the superior oblique (SO) extraocular muscle cross section in normal controls and in SO palsy using high-resolution magnetic resonance imaging (MRI). DESIGN Prospective observational study. METHODS At a single academic medical center, high-resolution MRI was obtained at 312 μm in-plane resolution using surface coils in multiple, contiguous, quasi-coronal planes perpendicular to the orbital axis in 12 controls and 62 subjects with SO palsy. Previous strabismus surgery was excluded. Imaging was repeated in central gaze and infraduction. In each image plane along the SO, its cross section was outlined to compute cross-sectional area and the major and minor axes of the best-fitting ellipse. Main outcome measures were SO morphology and ocular motility. RESULTS The major and minor axes, cross-sectional area distributions, and volume of the SO belly were subnormal in orbits with SO palsy at most anteroposterior locations (P = .001), but discriminant analysis showed that palsied SO cross sections segregated distinctly into round and elongate shapes representing isotropic vs anisotropic atrophy, respectively. The major axis was relatively preserved in anisotropic atrophy (P = .0146). Cases with isotropic atrophy exhibited greater hypertropia in infraversion than central gaze, as well as greater excyclotorsion, than cases with anisotropic atrophy (P < .05 for all). CONCLUSIONS Characteristic differences in shape of the palsied SO belly correlate with different clinical features, and may reflect both the degree of differential pathology in the medial vs lateral neuromuscular SO compartments and the basis for diversity in patterns of resulting hypertropia.
Collapse
|
27
|
Demer JL. Compartmentalization of extraocular muscle function. Eye (Lond) 2015; 29:157-62. [PMID: 25341434 PMCID: PMC4330271 DOI: 10.1038/eye.2014.246] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 08/29/2014] [Indexed: 01/18/2023] Open
Abstract
Ocular motor diversity exceeds capabilities of only six extraocular muscles (EOMs), but this deficiency is overcome by the plethora of fibers within individual EOMs surpassing requirements of homogeneous actuators. This paper reviews emerging evidence that regions of individual EOMs can be differentially innervated to exert independent oculorotary torques, broadening the oculomotor repertoire, and potentially explaining diverse strabismus pathophysiology. Parallel structure characterizes EOM and tendon fibers, with little transverse coupling of experimentally imposed or actively generated tension. This arrangement enables arbitrary groupings of tendon and muscle fibers to act relatively independently. Coordinated force generation among EOM fibers occurs only upon potentially mutable coordination of innervational commands, whose central basis is suggested by preliminary findings of apparent compartmental segregation of abducens motor neuron pools. Humans, monkeys, and other mammals demonstrate separate, nonoverlapping intramuscular nerve arborizations in the superior vs inferior compartments of the medial rectus (MR) and lateral rectus (LR) EOMs that could apply force at the superior vs inferior portions of scleral insertions, and in the medial vs lateral compartments of the superior oblique that act at the equatorial vs posterior scleral insertions that might preferentially implement incycloduction vs infraduction. Magnetic resonance imaging of the MR during several physiological ocular motor behaviors indicates differential compartmental function. Differential compartmental pathology can influence clinical strabismus. Partial abducens palsy commonly affects the superior LR compartment more than the inferior, inducing vertical strabismus that might erroneously be attributed to cyclovertical EOM pathology. Surgery may selectively manipulate EOM compartments.
Collapse
Affiliation(s)
- J L Demer
- Departments of Ophthalmology and Neurology, Stein Eye Institute, David Geffen Medical School, University of California, Los Angeles, CA, USA
| |
Collapse
|
28
|
Demer JL, Clark RA. Magnetic resonance imaging demonstrates compartmental muscle mechanisms of human vertical fusional vergence. J Neurophysiol 2015; 113:2150-63. [PMID: 25589593 DOI: 10.1152/jn.00871.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 01/09/2015] [Indexed: 11/22/2022] Open
Abstract
Vertical fusional vergence (VFV) normally compensates for slight vertical heterophorias. We employed magnetic resonance imaging to clarify extraocular muscle contributions to VFV induced by monocular two-prism diopter (1.15°) base-up prism in 14 normal adults. Fusion during prism viewing requires monocular infraduction. Scans were repeated without prism, and with prism shifted contralaterally. Contractility indicated by morphometric indexes was separately analyzed in medial and lateral vertical rectus and superior oblique (SO) putative compartments, and superior and inferior horizontal rectus extraocular muscle putative compartments, but in the whole inferior oblique (IO). Images confirmed appropriate VFV that was implemented by the inferior rectus (IR) medial compartment contracting ipsilateral and relaxing contralateral to prism. There was no significant contractility in the IR lateral compartment. The superior but not inferior lateral rectus (LR) compartment contracted significantly in the prism viewing eye, but not contralateral to prism. The IO contracted ipsilateral but not contralateral to the prism. In the infraducting eye, the SO medial compartment relaxed significantly, while the lateral compartment was unchanged; contralateral to prism, the SO lateral compartment contracted, while the medial compartment was unchanged. There was no contractility in the superior or medial rectus muscles in either eye. There was no globe retraction. We conclude that the vertical component of VFV is primarily implemented by IR medial compartment contraction. Since appropriate vertical rotation is not directly implemented, or is opposed, by associated differential LR and SO compartmental activity, and IO contraction, these actions probably implement a torsional component of VFV.
Collapse
Affiliation(s)
- Joseph L Demer
- Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and Department of Neurology, David Geffen Medical School, University of California, Los Angeles, California
| | - Robert A Clark
- Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and
| |
Collapse
|
29
|
Shin A, Yoo L, Demer JL. Independent active contraction of extraocular muscle compartments. Invest Ophthalmol Vis Sci 2014; 56:199-206. [PMID: 25503460 DOI: 10.1167/iovs.14-15968] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE Intramuscular innervation of horizontal rectus extraocular muscle (EOMs) is segregated into superior and inferior (transverse) compartments, whereas all EOMs are also divided into global (GL) and orbital (OL) layers with scleral and pulley insertions, respectively. Mechanical independence between both types of compartments has been demonstrated during passive tensile loading. We examined coupling between EOM compartments during active, ex vivo contraction. METHODS Fresh bovine EOMs were removed, and one compartment of each was coated with hydrophobic petrolatum. Contraction of the uncoated compartment was induced by immersion in a solution of 50 mM CaCl2 at 38°C labeled with sodium fluorescein dye, whereas tensions in both compartments were monitored by strain gauges. Control experiments omitted petrolatum so that the entire EOM contracted. After physiological experiments, EOMs were sectioned transversely to demonstrate specificity of CaCl2 permeation by yellow fluorescence dye excited by blue light. RESULTS In control experiments without petrolatum, both transverse and GL and OL compartments contracted similarly. Selective compartmental omission of petrolatum caused markedly independent compartmental contraction whether measured at the GL or the OL insertions or for transverse compartments at the scleral insertion. Although some CaCl2 spread occurred, mean (±SD) tension in the coated compartments averaged only 10.5 ± 3.3% and 6.0 ± 1.5% in GL/OL and transverse compartments, respectively relative to uncoated compartments. Fluorescein penetration confirmed selective CaCl2 permeation. CONCLUSIONS These data confirm passive tensile findings of mechanical independence of EOM compartments and extend results to active contraction. EOMs behave actively as if composed of mechanically independent parallel fiber bundles having different insertional targets, consistent with the active pulley and transverse compartmental hypotheses.
Collapse
Affiliation(s)
- Andrew Shin
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, California, United States
| | - Lawrence Yoo
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, California, United States
| | - Joseph L Demer
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, California, United States
| |
Collapse
|
30
|
Hypertropia in unilateral isolated abducens palsy. J AAPOS 2014; 18:235-40. [PMID: 24924275 PMCID: PMC4079534 DOI: 10.1016/j.jaapos.2014.01.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 12/29/2013] [Accepted: 01/05/2014] [Indexed: 11/22/2022]
Abstract
PURPOSE To evaluate the incidence and features of hypertropia in abducens nerve palsy. METHODS The records of consecutive patients with unilateral, isolated, previously unoperated abducens nerve palsy were reviewed for binocular alignment on cover testing, Krimsky measurement, or Hess screen testing. Patients with associated cranial nerve palsy (including bilateral abducens palsies), orbital disease, myasthenia gravis, Horner syndrome, hemiplegia, cerebellar signs, arteritis, or previous strabismus surgery were excluded. Control subjects underwent complete examination to confirm normality. RESULTS A total of 79 patients were included (40 males; mean age 49.2 years). Hypertropia in lateral or central gazes was present in 15 of 79 cases (19%) on alternate cover or Krimsky testing, in 32 of 56 cases (57%) on Hess screen testing, and absent in all 30 normal controls. Of cases with hypertropia, the mean of the greatest hypertropia in lateral or central gaze on was 5.0(Δ) ± 2.3(Δ) (standard deviation; range, 1(Δ)-8(Δ)) routine clinical examination, and 5.8(Δ) ± 4.2(Δ) (range, 2(Δ)-24(Δ)) on Hess screen testing. Of 39 cases with partial abducens palsy evaluated by Hess screen testing, the ipsilesional eye was hypertropic in 24 (61%) and hypotropic in 15 cases (39%). CONCLUSIONS Small-angle hypertropia is common in isolated, unilateral abducens and does not imply existence of multiple cranial neuropathies or skew deviation.
Collapse
|