Dissociated Palsy of Vertical Saccades: Loss of Voluntary and Visually Guided Saccades With Preservation of Reflexive Vestibular Quick Phases

Abstract

A patient with a diencephalic infarct displayed a persistent palsy of voluntary and visually guided vertical saccades with preserved vertical quick phases of vestibular nystagmus on magnetic search coil oculography. Vertical smooth pursuit had very low velocity in both directions without catch-up saccades. Vertical and torsional vestibulo-ocular reflex gains were normal. Preservation of vertical and torsional quick phases signifies integrity of the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). This case is the first to provide evidence that disruption of descending cerebral corticofugal pathways to the riMLF with preserved ascending projections from the paramedian pontine reticular formation to the riMLF can cause a dissociated palsy of vertical fast eye movements.

Aging Increases Compensatory Saccade Amplitude in the Video Head Impulse Test

“…Increased levels of cerebellar disinhibition in older adults may contribute to reduced VOR calibration and generation of over-compensatory saccades ( 27 ). Maladaptive interaction between the paramedian pontine reticular formation and the vestibular nuclei may also contribute to the relationship between VOR gain and saccade amplitude reported here ( 28 , 29 ). Although saccades triggered by target-driven head free gaze shifts were observed to be smaller and slower in older adults ( 30 ), compensatory saccades triggered by retinal slip or position error due to VOR insufficiency may result from a different neural mechanism or behave differently in the context of aging.…”

Vertikale Blickparesen bei dorsalem Mittelhirnsyndrom und anderen Erkrankungen

“…Es ist gut nachvollziehbar, dass sich dadurch bei Mittelhirnläsionen verschiedenartige Ausprägungen einer vBP mit diversen Begleitsymptomen ergeben können. So verursachen beispielsweise auch einseitige Mittelhirnläsionen unter Einbeziehung von riMLF und INC aber mit Aussparung der PC eine vBP nach oben oder in beide Richtungen mit oder ohne Dissoziation einzelner Blickmodalitäten [12][13][14][15][16][17] oder auch ein DMS [18,19]. Auch einseitige Thalamusläsionen können eine vBP in eine oder beide Richtungen verursachen [20].…”