Adaptations and deficits in the vestibulo-ocular reflex after sixth nerve palsy.
Notice bibliographique
Résumé
PURPOSE: The effects of paralytic strabismus on the vestibulo-ocular reflex (VOR) have not been systematically investigated in humans. The purpose of this study was to analyze the VOR in patients with unilateral peripheral sixth nerve palsy. METHODS: Twenty-one patients with unilateral peripheral sixth nerve palsy (6 severe, 7 moderate, 8 mild) and 15 normal subjects were studied. Subjects made sinusoidal +/-10 degrees head-on-body rotations in yaw and pitch at approximately 0.5 and 2 Hz, and in roll at approximately 0.5, 1, and 2 Hz. Eye movement recordings were obtained using magnetic scleral search coils in each eye in darkness and during monocular viewing in light. Static torsional VOR gains, defined as change in torsional eye position divided by change in head position during sustained head roll, were also measured. RESULTS: In all patients, horizontal VOR gains in darkness were decreased in the paretic eye in both abduction and adduction, but remained normal in the nonparetic eye in both directions. In light, horizontal visually enhanced VOR (VVOR) gains were normal in both eyes in moderate and mild palsy. In severe palsy, horizontal VVOR gains remained low in the paretic eye during viewing with either eye, whereas those in the nonparetic eye were higher than normal when the paretic eye viewed. Vertical VOR and VVOR were normal, but dynamic and static torsional VOR and VVOR gains were reduced in both eyes in all patients. CONCLUSIONS: In darkness, horizontal VOR gains were reduced during abduction of the paretic eye in all patients, as anticipated in sixth nerve palsy. Gains were also reduced during adduction of the paretic eye, suggesting that innervation to the medial rectus has changed. After severe palsy, vision did not increase abducting or adducting horizontal VVOR gains to normal in the paretic eye, but caused secondary increase in VVOR gains to values above unity in the nonparetic eye, when the paretic eye fixated. In mild and moderate palsy, vision enhanced the VOR in the paretic eye but caused no change in the nonparetic eye, suggesting a monocular readjustment of innervation selectively to the paretic eye. Vertical VOR and VVOR gains were normal, indicating that the lateral rectus did not have significant vertical actions through the excursions that we tested (+/-10 degrees ). Reduced torsional VOR gains in the paretic eye can be explained by the esotropia in sixth nerve palsy. Torsional VOR gain normally varies with vergence. We attribute the reduced torsional gains in the paretic eye to the mechanism that normally lowers it during convergence. The low torsional gains in the nonparetic eye may be an adaptation to reduce torsional disparity between the two eyes.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».