| Identifier |
thalamic_esotropia_lee |
| Title |
Thalamic Esotropia |
| Creator |
Andrew G. Lee, MD; Spencer Barrett |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (SB) Class of 2022, Baylor College of Medicine, Houston, Texas |
| Subject |
Midbrain; Pons; Vertical Gaze |
| Description |
Summary: • Thalamic Esotropia o Anatomical Review > CN III/IV in the midbrain > CN VI in the pons > Thalamo-mesencephalic junction > Vertical gaze control center o Pathophysiology of Thalamic Esotropia > Convergence Center: • Synkinetic Triad and Edinger-Westphal Nucleus > Over-activity of convergence center (CN III) > No paresis of CN VI o Epidemiology > Exceedingly rare finding > Should be considered in patients with thalamic lesions and esotropia |
| Transcript |
So today we're going to be talking about thalamic esotropia, and the thalamus is like a "way-station" for the convergence of information- both going up and coming down. So it's receiving a lot of information, it's processing a lot of information, and it's also the substation that modulates that information. So there's a lot of action going on in the thalamus. So even though the cranial nerves (CN III, CN IV, and CN VI) do not live in the thalamus-CN III and CN IV live in the midbrain and CN VI lives in the pons - the motor control for some supranuclear movements is mediated in the thalamus. So the two you need to know about are at the thalamo-mesencephalic junction. We have the control centers for the vertical gaze. You should look at that video on vertical gaze deviations. So patients who have dorsal midbrain syndromes, thalamic strokes, thalamo-mesencephalic junction lesions often have vertical gaze abnormalities because the vertical gaze center lives in the thalamo-mesencephalic junction. That is the rostral, interstitial, medial longitudinal fasciculus as well as the interstitial nucleus of Cajal: the vertical gaze center. That vertical gaze center is talking to cranial nerves III and IV. But today's topic is actually esotropia; that's because the near convergence center is also rostral to the dorsal midbrain. We don't know exactly where the conversion center is, but the convergence center is above the Edinger-Westphal nucleus in the midbrain. So we have the thalamo-mesencephalic near-and-convergence center talks to the third nerve nucleus, including the Edinger-Westphal in the midbrain, to both constrict the pupils and to converge, and that is a synkinetic triad at near. So when we look at something at near our pupil get smaller, we converge, and we change the accommodated power of our lens so we can read at near. That synkinetic triad is probably being mediated at the level of the thalamus in the near convergence center. Therefore you can get convergence spasm leading to an esotropia, even though that has nothing to do with the six nerve which lives in the pons. It's over-action of the medial rectus, rather than under-action of the lateral rectus. So sometimes with a thalamic lesion we can get an esotropia, but that's from too much medial rectus firing. Probably from too much convergence from the convergence center to the third nerve in the midbrain. So thalamic esotropia is a very uncommon finding. However, you should be considering it in patients who have thalamic lesions, who have anesotropia, and the mechanism is probably convergent spasm and not paresisor related in the six nerve and all, which lives in the pons. |
| Date |
2021-04 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Andrew G. Lee Collection: https://novel.utah.edu/Lee/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah, 10 N 1900 E SLC, UT 84112-5890 |
| Rights Management |
Copyright 2019. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s6h47p48 |
| Setname |
ehsl_novel_lee |
| ID |
1680631 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s6h47p48 |
