Comparison of Muscle Volume Between Congenital and Acquired Superior Oblique Palsies by Magnetic Resonance Imaging

Sato, M.; Yagasaki, Teiji; Kora, Toshitake; Awaya, S

doi:10.1016/s0021-5155(98)00044-6

Cited by 29 publications

(18 citation statements)

References 5 publications

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“…It must be recognized that muscle force has two separate components: active contractile force controlled by innervation, and passive elastic force determined by stiffness and muscle stretching. 31 In the present study as well as in previous studies, 8,10 MRI demonstrated that about half of the subjects exhibited a normal cross-sectional size. Demer 10 reported that the pattern of binocular misalignment observed in such cases is explainable by passive elastic abnormalities of the SO.…”

Section: Discussionsupporting

confidence: 80%

Displacement of the rectus muscle pulleys simulating superior oblique palsy

et al. 2008

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Section: Discussionsupporting

confidence: 80%

Displacement of the rectus muscle pulleys simulating superior oblique palsy

et al. 2008

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“…13,56,57 On the basis of the present results, it would be anticipated that appropriate orbital MRI in humans would demonstrate neurogenic atrophy of the deep SO belly within 5 weeks of denervation. The fine time scale of this prediction remains to be confirmed in humans.…”

Section: Discussionmentioning

confidence: 72%

Effects of Intracranial Trochlear Neurectomy on the Structure of the Primate Superior Oblique Muscle

Demer

Poukens²,

Ying³

et al. 2010

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Although cyclovertical strabismus in humans is frequently attributed to superior oblique (SO) palsy, anatomic effects of SO denervation have not been studied. Magnetic resonance imaging (MRI) and orbital histology was used to study the effects of acute trochlear (CN4) denervation on the monkey SO. METHODS. Five juvenile macaque monkeys were perfused with formalin for 5 weeks: 15 months after unilateral or bilateral 10-mm intracranial trochlear neurectomy. Denervated and fellow orbits were imaged by MRI, embedded whole in paraffin, serially sectioned at 10-mum thickness, and stained with Masson trichrome. Whole muscle and individual fiber cross sections were quantified in SO muscles throughout the orbit and traced larger fibers in one specimen where they were present. RESULTS. MRI demonstrated marked reduction in midorbital cross section in denervated SO muscles, with anterior shift of SO mass preserving overall volume. Muscle fibers exhibited variable atrophy along their lengths. Denervated orbital layer (OL) fiber cross sections were slightly but significantly reduced from control at most anteroposterior locations, but this reduction was much more profound in global layer (GL) fibers. Intraorbital and intramuscular CN4 were uniformly fibrotic. In one animal, there were scattered clusters of markedly hypertrophic GL fibers that exhibited only sparse myomyous junctions only anteriorly. CONCLUSIONS. CN4 denervation produces predominantly SO GL atrophy with relative OL sparing. Overall midorbital SO atrophy was evident by MRI as early as 5 weeks after denervation, as denervated SO volume shifted anteriorly. Occasional GL fiber hypertrophy suggests that at least some SO fibers extend essentially the full muscle length after trochlear neurectomy.

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“…However, the present study found the SO to be smaller in congenital than in acquired SO palsy, confirming the report of Sato et al . 28 This difference in SO size may be due to the different etiologies, with the smaller SO in congenital palsy perhaps caused either by primary hypoplasia or by denervation atrophy, 27, 29, 37, 38 but the latter perhaps the sole cause in acquired palsy. 16 …”

Section: Discussionmentioning

confidence: 99%

Rectus Pulley Displacements without Abnormal Oblique Contractility Explain Strabismus in Superior Oblique Palsy

Suh

Clark

et al. 2016

Ophthalmology

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Purpose Using high-resolution magnetic resonance imaging (MRI), we investigated whether rectus pulleys are significantly displaced in superior oblique (SO) palsy, and if displacements account for strabismus patterns. Design Prospective, case-control study. Participants Twenty-four patients diagnosed with SO palsy based on atrophy of SO muscle on MRI, and 19 age-matched orthotropic control subjects. Methods High resolution, surface coil MRI was obtained in multiple, contiguous, quasicoronal planes during monocular central gaze fixation. Pulley locations in oculocentric coordinates in the following subgroups of patients with SO palsy were compared with normal in subgroups of patients with SO palsy: unilateral vs bilateral, congenital vs acquired, and isotropic (round shape) vs anisotropic (elongated shape) SO atrophy. Expected effects of pulley displacements were modeled using Orbit 1.8® computational simulation. Main outcome measures Rectus pulley positions and ocular torsion. Results Rectus pulleys were typically displaced in SO palsy. In unilateral SO palsy, on average the medial rectus (MR) pulley was displaced 1.1 mm superiorly, the superior rectus (SR) pulley 0.8 mm temporally, and the inferior rectus (IR) pulley 0.6 mm superior and 0.9 mm nasal from normal. Displacements were similar in bilateral SO palsy, with SR pulley additionally displaced 0.9 mm superiorly. However, the lateral rectus (LR) pulley was not displaced in either unilateral or bilateral SO palsy. The SR and MR pulleys were displaced in congenital SO palsy, while the IR and MR pulleys were displaced in acquired palsy. Pulley positions did not differ between isotropic and anisotropic palsy, or between patients with cyclotropia <7° versus ≥7°. Simulations predicted that the observed pulley displacements alone could cause patterns of incomitant strabismus typical of SO palsy, without requiring any abnormality of SO or inferior oblique strength. Conclusion Rectus pulley displacements alone, without abnormal oblique muscle contractility, can create the clinical patterns of incomitant strabismus in SO palsy. This finding supports accumulating evidence that clinical binocular misalignment patterns are not reliable indicators of contractile function of the SO muscle. Ocular torsion does not correlate with and thus cannot account for pulley displacements in SO palsy.

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Comparison of Muscle Volume Between Congenital and Acquired Superior Oblique Palsies by Magnetic Resonance Imaging

Cited by 29 publications

References 5 publications

Displacement of the rectus muscle pulleys simulating superior oblique palsy

Displacement of the rectus muscle pulleys simulating superior oblique palsy

Effects of Intracranial Trochlear Neurectomy on the Structure of the Primate Superior Oblique Muscle

Rectus Pulley Displacements without Abnormal Oblique Contractility Explain Strabismus in Superior Oblique Palsy

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