Faculty of Medicine
Library of the School of Health Sciences

2022-06-10

2022

Kemanetzoglou Elissavet

Ευαγγελία Καραρίζου, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ, Επιβλέπουσα
Νικόλαος Σμυρνής, Καθηγητής, Ιατρική Σχολ;h, ΕΚΠΑ
Κλειώ Χατζηστεφάνου, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Παναγιώτης Κοκοτής, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Μιχαήλ Ρέντζος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Αναστάσιος Μπονάκης, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Ανδρέας Κυρώζης, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ

Μελέτη των σακκαδικών οφθαλμικών κινήσεων σε ετερόπλευρη πάρεση έκτης εγκεφαλικής συζυγίας

Greek

Study of saccadic eye movements in unilateral sixth nerve palsy

INTRODUCTION: Despite the fact that abducens nerve palsy (ANP) is the most common ocular motor palsy, the literature on the respective saccade dynamics, both in the paretic and non-paretic eye, is scarce. AIMS AND METHODOLOGY: The aim of this study was to examine the maximum velocity, duration and accuracy of horizontal saccades, in individuals with unilateral ANP, and to compare them with normal controls. Binocular horizontal eye movements were recorded at 5, 10 and 15 degrees, using an infrared corneal reflection device from 21 adults with microvascular unilateral ANP during the acute and the chronic phase of the palsy, as well as 18 healthy adults. Non-parametric tests were used for statistical comparisons. RESULTS: The paretic eye, when compared to the non-paretic eye, presents a slightly lower saccadic amplitude and velocity/amplitude ratio and a higher duration/amplitude ratio. The non-paretic eye, compared to the healthy eye of the control group, showed consistently amplitude gain >1 while the velocity/amplitude ratio did not differ in either session. The duration/amplitude ratio tended to be higher in the non-paretic eye. The prism dioptres of the paretic eye did not appear to correlate with any parameter tested (amplitude gain, velocity/amplitude ratio, duration/amplitude ratio) of the open non-paretic eye, but the amplitude ratio was statistically lower during the 1st session when the non-paretic eye was kept covered and the duration/amplitude ratio decreased significantly. CONCLUSIONS: One of the main findings of the study is the increase in saccade duration during adaptation of ANP. Specifically, the non-paretic eye performed orthometric saccades with a longer duration than healthy controls. Given that the motor command reaches the ocular muscles by neural discharges with a "pulse-step" pattern, any adaptation reflects in a change of this pattern. Cerebellar learning leads to an increase in the pulse width of the neural discharge. This idiosyncratic response may be related to plastic changes in central structures that serve learning processes such as the cerebellum. Further research could provide more insight into the cerebellar plastic processes involved in the saccadic adaptation.

Health Sciences

Saccades, Unilateral abducens palsy, Diplopia, Pulse - step model saccade adaptation, Cerebellar learning

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https://pergamos.lib.uoa.gr/uoa/dl/object/3218364