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Graefe's Archive For Clinical and... Nov 2022Extraocular muscle enlargement can occur secondary to a range of orbital and systemic diseases. Although the most common cause of extraocular muscle enlargement is... (Review)
Review
Extraocular muscle enlargement can occur secondary to a range of orbital and systemic diseases. Although the most common cause of extraocular muscle enlargement is thyroid eye disease, a range of other inflammatory, infective, neoplastic, and vascular conditions can alter the size and shape of the extraocular muscles. Imaging with computed tomography and magnetic resonance imaging plays an essential role in the workup of these conditions. This article provides an image-rich review of the wide range of pathology that can cause enlargement of the extraocular muscles.
Topics: Humans; Oculomotor Muscles; Tomography, X-Ray Computed; Graves Ophthalmopathy; Magnetic Resonance Imaging; Hypertrophy
PubMed: 35713708
DOI: 10.1007/s00417-022-05727-1 -
Experimental Physiology Jan 2024Proprioception is the sense that lets us perceive the location, movement and action of the body parts. The proprioceptive apparatus includes specialized sense organs... (Review)
Review
Proprioception is the sense that lets us perceive the location, movement and action of the body parts. The proprioceptive apparatus includes specialized sense organs (proprioceptors) which are embedded in the skeletal muscles. The eyeballs are moved by six pairs of eye muscles and binocular vision depends on fine-tuned coordination of the optical axes of both eyes. Although experimental studies indicate that the brain has access to eye position information, both classical proprioceptors (muscle spindles and Golgi tendon organ) are absent in the extraocular muscles of most mammalian species. This paradox of monitoring extraocular muscle activity in the absence of typical proprioceptors seemed to be resolved when a particular nerve specialization (the palisade ending) was detected in the extraocular muscles of mammals. In fact, for decades there was consensus that palisade endings were sensory structures that provide eye position information. The sensory function was called into question when recent studies revealed the molecular phenotype and the origin of palisade endings. Today we are faced with the fact that palisade endings exhibit sensory as well as motor features. This review aims to evaluate the literature on extraocular muscle proprioceptors and palisade endings and to reconsider current knowledge of their structure and function.
Topics: Animals; Oculomotor Muscles; Sensory Receptor Cells; Mechanoreceptors; Proprioception; Muscle Spindles; Mammals
PubMed: 36869596
DOI: 10.1113/EP090765 -
Asia-Pacific Journal of Ophthalmology... 2018Myasthenia gravis is a relatively common neuromuscular disorder, with ocular myasthenia gravis being a subset defined as myasthenia gravis limited to the orbicularis,... (Review)
Review
Myasthenia gravis is a relatively common neuromuscular disorder, with ocular myasthenia gravis being a subset defined as myasthenia gravis limited to the orbicularis, levator, and extraocular muscles. Patients with ocular myasthenia gravis can have disabling diplopia or functional blindness from ptosis and in most cases treatment is required. Like generalized myasthenia gravis, there are a variety of treatments available that include pyridostigmine, immunosuppression, intravenous immunoglobulin, plasmapheresis, thymectomy, lid crutches, ptosis surgery, and extraocular muscle surgery. Unfortunately, there is limited data on the use of individual treatments in ocular myasthenia gravis and no data comparing treatments. Using a combination of available data on treatment of generalized myasthenia gravis, data on treatment of ocular myasthenia gravis, best practices, and clinical experience we will provide a rational framework for treatment of ocular myasthenia gravis.
Topics: Eye Movements; Humans; Immunosuppression Therapy; Myasthenia Gravis; Oculomotor Muscles; Ophthalmologic Surgical Procedures; Plasmapheresis; Prognosis; Visual Acuity
PubMed: 30044061
DOI: 10.22608/APO.2018301 -
AJNR. American Journal of Neuroradiology Apr 2022While Graves disease is the most common cause of extraocular muscle enlargement, case reports have also associated growth hormone-secretory pituitary adenomas with this...
BACKGROUND AND PURPOSE
While Graves disease is the most common cause of extraocular muscle enlargement, case reports have also associated growth hormone-secretory pituitary adenomas with this same phenomenon. We investigated the prevalence and response to treatment of extraocular muscle enlargement in patients with growth hormone-secretory pituitary adenomas.
MATERIALS AND METHODS
We retrospectively reviewed extraocular muscle sizes using MR imaging in patients with growth hormone-secretory pituitary adenomas who underwent a transsphenoidal surgical resection compared with a matched control group with nonsecretory pituitary adenomas. Descriptive and comparative statistics were used to evaluate patient characteristics and extraocular muscle sizes between the 2 groups.
RESULTS
We identified 16 patients who presented with growth hormone-secreting pituitary adenomas and underwent transsphenoidal surgical resection from 2010 to 2019. The average diameter of the extraocular muscle at the time of diagnosis for the group with growth hormone-secretory pituitary adenomas was larger than that in the control group (4.7 versus 3.8 mm, < .001). Nine patients achieved insulin-like growth factor 1 level normalization at a median of 11.5 months before their most recent MR imaging evaluation. The average size of the extraocular muscles of patients who achieved a normalized insulin-like growth factor 1 was smaller compared with those that did not (difference, 0.7 mm; 95% CI, 0.3-1.2 mm; < .001), approaching the size of extraocular muscle in the control group.
CONCLUSIONS
We describe a high prevalence of extraocular muscle enlargement in patients with growth hormone-secreting pituitary adenomas. Additionally, we note that the size of extraocular muscles decreased with associated improvement in the biochemical control of acromegaly.
Topics: Adenoma; Growth Hormone-Secreting Pituitary Adenoma; Human Growth Hormone; Humans; Insulin-Like Growth Factor I; Oculomotor Muscles; Pituitary Neoplasms; Retrospective Studies; Treatment Outcome
PubMed: 35301224
DOI: 10.3174/ajnr.A7453 -
Eye (London, England) Feb 2015Ocular motor diversity exceeds capabilities of only six extraocular muscles (EOMs), but this deficiency is overcome by the plethora of fibers within individual EOMs... (Review)
Review
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.
Topics: Animals; Humans; Motor Neurons; Ocular Motility Disorders; Oculomotor Muscles
PubMed: 25341434
DOI: 10.1038/eye.2014.246 -
Japanese Journal of Ophthalmology May 2024This study aimed to investigate the factors affecting extraocular muscle enlargement in thyroid eye disease (TED).
PURPOSE
This study aimed to investigate the factors affecting extraocular muscle enlargement in thyroid eye disease (TED).
STUDY DESIGN
Retrospective study.
METHODS
The 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.
RESULTS
The 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.
CONCLUSIONS
TSAb 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.
Topics: Humans; Oculomotor Muscles; Male; Female; Retrospective Studies; Graves Ophthalmopathy; Middle Aged; Autoantibodies; Magnetic Resonance Imaging; Adult; Aged; Thyroid Gland; Immunoglobulins, Thyroid-Stimulating
PubMed: 38609717
DOI: 10.1007/s10384-024-01061-7 -
Investigative Ophthalmology & Visual... Nov 2022This study aimed to clarify the formation and fixation of the annulus of Zinn (AZ) and its relationship with the extraocular muscles by using ultrathin plastination and...
PURPOSE
This study aimed to clarify the formation and fixation of the annulus of Zinn (AZ) and its relationship with the extraocular muscles by using ultrathin plastination and three-dimensional models.
METHODS
Eighteen cadaveric heads (36 sides of the orbital apex) were plastinated to coronal (16 sides), sagittal (13 sides), and horizontal (5 sides) ultrathin plastination sections to be investigated at both macroscopic and microscopic levels. One cadaveric head was used for endoscopic dissection to identify anatomic landmarks.
RESULTS
There were two fibrous triangles adhered to both ends of the anterior surface of the optic strut. The superior rectus muscle originated from the superior fibrous triangle, and the lateral, inferior, and medial rectus muscles emerged from the inferior fibrous triangle. It was not until 5.46 ± 0.41 mm anterior to the optic strut that the complete tendinous ring composed of rectus muscles, optic nerve sheath, and periosteum was formed. The superior oblique and levator palpebrae superioris muscles originated from the medial fibrous band of the AZ. At the posterior of the AZ, there was a potential passage between the medial rectus muscle and the optic nerve.
CONCLUSIONS
The fixation of the AZ was composed of the connection of the annular tendon to the optic strut posteriorly and the attachment of the complete tendinous ring to the lesser and greater wings of the sphenoid bone anteriorly. The triangular route area between the optic nerve and medial rectus muscle was located on the anterior side of the base of the optic strut.
Topics: Humans; Oculomotor Muscles; Plastination; Tendons; Optic Nerve; Cadaver
PubMed: 36355368
DOI: 10.1167/iovs.63.12.16 -
Ophthalmic Research 2021Paralytic strabismus involves a functional loss of extraocular muscles resulting from muscular or neuronal disorders. Currently, only a limited number of drugs are...
INTRODUCTION
Paralytic strabismus involves a functional loss of extraocular muscles resulting from muscular or neuronal disorders. Currently, only a limited number of drugs are available for functional repair of extraocular muscles. Here, we investigated the effects of a novel drug, flavonoids sophoranone, on the differentiation of extraocular muscles as assessed in bothin vivo and in vitro models.
MATERIALS AND METHODS
The effect of flavonoids sophoranone on C2C12 cells was examinedin vitro as evaluated with use of apoptosis, reactive oxygen species (ROS), and cell viability assays. Then, both in vivo and in vitro effects of this drug were examined on the differentiation of C2C12 and satellite cells within extraocular muscles in rabbits. For these latter experiments, RT-PCR and Western blot assays were used to determine expression levels of markers for myogenic differentiation.
RESULTS
With use of flavonoids sophoranone concentrations ranging from 0 to 10 μM, no effects were observed upon cell apoptosis, ROS, and cell cycle in C2C12 cells. Based on MTT assay results, flavonoids sophoranone was shown to increase C2C12 cell proliferation. Moreover, flavonoids sophoranone promoted the differentiation of C2C12 and satellite cells within extraocular muscles in rabbits, which were verified as based on cell morphology and expression levels of mRNA and protein markers of myogenic differentiation. Finally, flavonoids sophoranone treatment also increased gene expressions of Myh3, Myog, and MCK.
CONCLUSION
The capacity for flavonoids sophoranone to upgrade the differentiation of both C2C12 and satellite cells within extraocular muscles in rabbits at concentrations producing no adverse effects suggest that this drug may provide a safe and effective means to promote repair of damaged extraocular muscles.
Topics: Animals; Apoptosis; Cell Cycle; Cell Differentiation; Cell Proliferation; Cells, Cultured; Flavonoids; Models, Animal; Muscle Development; Myoblasts; Oculomotor Muscles; Rabbits; Reactive Oxygen Species
PubMed: 32344402
DOI: 10.1159/000508251 -
Sichuan Da Xue Xue Bao. Yi Xue Ban =... Nov 2021The superior oblique muscle has the longest tendon among the six extraocular muscles and serves complex functions. Surgery on the superior oblique muscle is considered... (Review)
Review
The superior oblique muscle has the longest tendon among the six extraocular muscles and serves complex functions. Surgery on the superior oblique muscle is considered the most complicated and difficult procedure in the field of strabismus. This article focuses on the history of superior oblique muscle surgeries, including superior oblique weakening procedure and superior oblique strengthening procedure. We discussed the advantages, disadvantages, and indications of each type of surgery, providing colleagues in the field of ophthalmology with a comprehensive understanding of superior oblique muscle surgery and facilitating the carefully weighed decision to choose and perform the procedure.
Topics: Humans; Oculomotor Muscles; Strabismus; Tendons
PubMed: 34841752
DOI: 10.12182/20211160201 -
Graefe's Archive For Clinical and... Jul 2023Strabismus is not a condition in itself but the consequence of an underlying problem. Eye misalignment can be caused by disease, injury, and/or abnormalities in any of... (Review)
Review
Strabismus is not a condition in itself but the consequence of an underlying problem. Eye misalignment can be caused by disease, injury, and/or abnormalities in any of the structures and processes involved in visual perception and oculomotor control, from the extraocular muscles and their innervations to the oculomotor and visual processing areas in the brain. A small percentage of all strabismus cases are the consequence of well-described genetic syndromes, acquired insult, or disease affecting the extraocular muscles (EOMs) or their innervations. We will refer to them as strabismus of peripheral origin since their etiology lies in the peripheral nervous system. However, in most strabismus cases, that is comitant, non-restrictive, non-paralytic strabismus, the EOMs and their innervations function properly. These cases are not related to specific syndromes and their precise causes remain poorly understood. They are generally believed to be caused by deficits in the central neural pathways involved in visual perception and oculomotor control. Therefore, we will refer to them as central strabismus. The goal of this narrative review is to discuss the possible causes behind this particular type of eye misalignment and to raise awareness among eyecare professionals about the important role the central nervous system plays in strabismus etiology, and the subsequent implications regarding its treatment. A non-systematic search was conducted using PubMed, Medline, Cochrane, and Google Scholar databases with the keywords "origins," "causes," and "etiology" combined with "strabismus." A snowball approach was also used to find relevant references. In the following article, we will first describe EOM integrity in central strabismus; next, we will address numerous reasons that support the idea of central nervous system (CNS) involvement in the origin of the deviation, followed by listing several possible central causes of the ocular misalignment. Finally, we will discuss the implications CNS etiology has on strabismus treatment.
Topics: Humans; Oculomotor Muscles; Syndrome; Strabismus; Eye Movements; Central Nervous System
PubMed: 36680614
DOI: 10.1007/s00417-022-05935-9