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Horizontal gaze palsies can be caused by a lesion affecting any structure in these pathways. Lesions to abducens nucleus or PPRF typically create an ipsilateral gaze palsy, while lesions to MLF typically cause Internuclear ophthalmoplegia , a type of horizontal gaze palsy in which the affected eye cannot adduct in conjugation with the ...
As seen in horizontal saccadic palsy, the impairment of the contralateral side gaze is caused by the disrupted pathways coming from the PPRF, while the "half" impairment is from the signal passing through the medial longitudinal fascicles not being able to reach its target. One-and-a-Half syndrome is normally associated with horizontal gaze.
More formally, it is characterized by "a conjugate horizontal gaze palsy in one direction and an internuclear ophthalmoplegia in the other". [1] [2] Nystagmus is also present when the eye on the opposite side of the lesion is abducted. Convergence is classically spared as cranial nerve III (oculomotor nerve) and its nucleus is spared bilaterally.
Loss of horizontal saccades directed towards the side of the lesion, no matter the current position of gaze; Contralateral gaze deviation (acute lesions, such as early stroke, only) Gaze-evoked lateral nystagmus on looking away from the side of the lesion; Bilateral lesions produce horizontal gaze palsy and slowing of vertical saccades
The diagnostic criteria for Athabaskan brainstem dysgenesis syndrome include: [1] Verification of sensorineural deafness by brainstem auditory evoked responses. [1]Upon conjugate lateral gazing, there is horizontal gaze palsy; however, the medial gaze remains intact with convergence.
The conjugate gaze is the motion of both eyes in the same direction at the same time, and conjugate gaze palsy refers to an impairment of this function. The conjugate gaze is controlled by four different mechanisms: [4] the saccadic system that allows for voluntary direction of the gaze; the pursuit system that allows the subject to follow a ...
Patients will move their heads to adjust for the loss of peripheral vision caused by inability to abduct or adduct the eye. All directions of gaze are affected; however, downward gaze appears to be best spared. This is in contrast to progressive supranuclear palsy (PSP), which typically affects vertical gaze and spares horizontal gaze.
Foville's syndrome is caused by the blockage of the perforating branches of the basilar artery in the region of the brainstem known as the pons. [1] It is most frequently caused by lesions such as vascular disease and tumors involving the dorsal pons.