Characteristics of vestibular corrective saccades in patients with slow visual saccades, vestibular disorders and controls: A descriptive analysis

Abstract

ObjectiveOur aim was to determine whether overt catch up saccades (OS) provoked by vestibular stimuli, as observed in the video head impulse test (vHIT), have comparable metrics as visually triggered horizontal saccades (VS), indicating a common saccadic brainstem generator.MethodsThree groups of patients were studied: patients with neurological disorders causing slow saccades (group 1, n = 12), patients with peripheral vestibular lesions (group 2, n = 43), and normal controls (group 3, = 24). All patients underwent vHIT and Videooculographic testing. OS velocity, acceleration, amplitude and duration and VS velocity in this group was compared between the groups.ResultsThere was significant reduction in the velocity of visually guided saccades in group 1, as expected from the patient selection constraints of this study. Group 1 also exhibited saccades which were longer in duration and of reduced acceleration when compared to subjects without saccadic slowing to visual targets (Group 2 and 3). There were significant positive correlations between OS acceleration and amplitude in both normal saccade groups (2 and 3) which was not observed in the slow saccade group (1).ConclusionsThe metrics of overt saccades measured by the vHIT in patients with slow saccades and normal controls are similar to visually guided saccades. This supports the hypothesis that overt saccades associated with vestibular stimuli and visually triggered saccades share common circuitry that controls metrics.

Simultaneous Presentation of Definite Vestibular Migraine and Definite Ménière's Disease: Overlapping Syndrome of Two Diseases

“…At least 8 valid head impulses were recorded in each plane of each semicircular canal. The VOR gains during the vHIT (eye velocity/head velocity) were automatically measured using software that computed the slope of the regression between head and eye velocity ( 13 ). When a mean gain in vHIT of < 0.7 for the vertical canals or < 0.8 for the lateral canals was detected and catch-up (corrective) saccades were observed, the relevant canal was regarded to be functioning abnormally ( 14 ).…”

Aging and Eye Tracking: in the Quest for Objective Biomarkers

“…Thus, saccades can be analyzed and studied in relation with the tasks and stimuli. Involuntary saccades may occur during sleep (rapid eye movements) [30], in the form of microsaccades, and as vestibular ocular reflex (catch-up saccades) [31,32]. There are experimental paradigms that enable different forms of saccades including express saccades with shorter latencies than other types of saccades [33].…”

Sensibilidade e especificidade do video head impulse test no diagnóstico do recrutamento vestibular pós-calórico

“…Na fase aguda e descompensada da lesão vestibular, essas sacadas são descobertas e acontecem após o término do movimento da cabeça. Durante o processo de compensação vestibular as sacadas apresentam latências cada vez mais próximas à resposta do reflexo e passam a ocorrer durante o movimento da cabeça (Weber et al, 2009;Yacovino et al, 2018a). Estas sacadas, que acontecem antes do término do movimento cefálico, são denominadas sacadas cobertas.…”

“…Durante o processo de compensação vestibular essa sacada apresenta latências cada vez mais próximas do retorno da cabeça ao repouso e passa a ocorrer durante o movimento da cabeça. A sacada passa a ocorrer precocemente, com latência em torno de 100 ms. E recebe agora o nome de sacada coberta (covert) (Weber et al, 2009;Yacovino et al, 2018a). As sacadas cobertas são atribuídas a um sistema de compensação central que antecipa a posição final do olho em função do movimento cefálico esperado (Tjernstro et al, 2012) e colaborapara manter a acuidade visual dinâmica (Hermann et al, 2018).…”

“…Levando em consideração esse fato, Barin (2019) propôs que o cálculo da média dos ganhos direito e esquerdo possa estimar a perda da função vestibular, estimativa que apresenta alta precisão em lesões vestibulares unilaterais. (Yacovino et al, 2018a).…”