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Head and Neck Muscles
Published in Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Handbook of Muscle Variations and Anomalies in Humans, 2022
Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Warrenkevin Henderson, Hannah Jacobson, Noelle Purcell, Kylar Wiltz
The absence of lateral rectus may be associated with convergent strabismus (Macalister 1875; Whitnall 1921; Sandall and Morrison 1979; Zöller et al. 2001). Park and Oh (2003) found that an accessory lateral rectus was associated with exotropia, ptosis, pupil dilation, and limited eye movement. Symptoms associated with accessory lateral rectus muscles may be diagnosed as exotropic Duane syndrome (Pineles and Velez 2015; Neves and Curi 2019).
Cranial Neuropathies II, III, IV, and VI
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Tanyatuth Padungkiatsagul, Heather E. Moss
The nucleus of the CN VI is located in the dorsal pons (Figures 22.20, 22.21). The genu of the CN VII fascicle wraps around it, corresponding with facial colliculus on external surface of the pons. The CN VI fascicles travel through the body of the pons ventrally, passing through the cortical spinal tracts. In the posterior fossa, the CN VI ascends from the pontomedullary junction along clivus and passed under Gruber's ligament into Dorello's canal and the cavernous sinus. While in the cavernous sinus, the postganglionic sympathetic fibers to the pupil join the CN VI for a short distance. Ultimately, it innervates the ipsilateral lateral rectus muscle in each eye.
Practice exam 2: Answers
Published in Euan Kevelighan, Jeremy Gasson, Makiya Ashraf, Get Through MRCOG Part 2: Short Answer Questions, 2020
Euan Kevelighan, Jeremy Gasson, Makiya Ashraf
Wernicke’s encephalopathy is caused by a deficiency in vitamin B1 (thiamine). Clinical features include diplopia, abnormal ocular movements, including sixth-nerve palsy [lateral rectus muscle], nystagmus, ataxia and confusion (1). [Features on magnetic resonance imaging are symmetrical lesions around the aqueduct and fourth ventricle.] Prophylactic administration of thiamine to patients with hyperemesis gravidarum and not giving intravenous fluids containing dextrose can prevent Wernicke’s encephalopathy (2).
Objective excyclotorsion increases with aging in adults
Published in Strabismus, 2022
Two reasons can be proposed as the causes of this increase in the cyclotorsion of older people. The first is age-related sagging of the lateral rectus muscle due to connective attrition of the lateral rectus and superior rectus (LR-SR) band.17 The sagging of the lateral rectus muscle shifts its pulling direction. This shift may produce deorsum- and excycloduction as new secondary actions of the lateral rectus muscle, which is found in sagging eye syndrome.17 The second is the decrease in phoria adaptation with age.18,19 Excyclophoria is the baseline state of binocular alignment in adults,16,20 and a decrease in phoria adaptation after prolonged monocular occlusion uncovers this latent excyclophoria.20 Older people still have a good cyclofusion ability.16 Good fusional ability enables older people to overcome the increased DFA (or increased excyclophoria) and prevent suffering from cyclotorsion diplopia.
Comparison of Unilateral and Bilateral Surgical Approaches for the Treatment of Age-Related Divergence Insufficiency Esotropia
Published in Journal of Binocular Vision and Ocular Motility, 2022
Chavisa Bunyavee, Steven M. Archer, Chris Y. Wu, Monte A. Del Monte
Divergence insufficiency is a form of esodeviation that measures greater at distance, less or absent at near. Diplopia is often present only at distance fixation.1–3 Its clinical description first appeared in the medical literature more than a century ago and has been classified mostly depending on the presence of an associated neurologic pathology.4,5 Divergence insufficiency found in older adults without any neurologic sign is defined as age-related divergence insufficiency esotropia (ARDIE). It is also known as age-related distance esotropia,6 divergence insufficiency pattern esotropia,7 or divergence paralysis esotropia as a manifestation of sagging eye syndrome.8,9 Proposed etiologies include central or peripheral microvascular 6th nerve palsy, abnormal position of rest, decreased medial rectus muscle elasticity, increased convergence tonus with resulting shortening of the medial rectus muscles, and degeneration of the intermuscular connective tissue band between the lateral and superior rectus muscles resulting in the inferior displacement of the lateral rectus muscles (sagging eye syndrome).10–13 ARDIE has been increasingly diagnosed in the past decade, and symptoms can markedly affect patients’ quality of life.14
Clinical Features of Crowded Orbital Syndrome on Magnetic Resonance Imaging
Published in Neuro-Ophthalmology, 2021
Mayumi Iwasa, Masato Wakakura, Hiromi Kohmoto, Sonoko Tatsui, Hitoshi Ishikawa
The COS group in this study usually showed no temporal tilting of the lateral rectus muscle, unlike in sagging eye syndrome.5,6 However, the lateral rectus muscle was in contact with the eyeball, as observed in patients with heavy eye syndrome (Figure 3).7,8 It is also observed in relatively young people, who are not expected to have sagging eye syndrome. These young patients do not have deep superior sulci in the upper eyelids. In terms of MRI characteristics, the COS group might overlap with heavy eye syndrome. Many patients in the COS group who were mildly affected had shorter ocular axes and smaller dislocation angles than those with heavy eye syndrome reported previously.2,3,7 According to Tan et al.,8 heavy eye syndrome presents with esotropia and limited abduction due to the superotemporal globe shift relative to the extraocular muscles. In general, heavy eye syndrome refers to strabismus fixus or a state similar to it. COS differs from heavy eye syndrome in that it does not have associated eye movement disorders.