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A horizontal gaze palsy is a subtype of gaze palsy in which conjugate, horizontal eye movements are limited by neurologic deficits. Horizontal gaze palsies typically result from an ipsilateral pontine lesion or a contralateral frontal lobe lesion.
The location of the lesion determines the type of palsy. Nonselective horizontal gaze palsies are caused by lesions in the Abducens nucleus.This is where the cranial nerve VI leaves on its way to the Lateral rectus muscle, which controls eye movement horizontally away from the midline of the body.
Destructive lesions of the PPRF cause ipsilateral horizontal conjugate gaze palsy and mostly impair ipsilateral horizontal saccades, however, other horizontal and vertical eye movements may also be affected as the PPRF contains multiple distinct populations of neurons important in saccade generation, as well as being traversed by nerve fibers ...
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.
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.
Conjugate gaze palsy: Conjugate gaze palsies typically affect horizontal gaze, although some affect upward gaze. Few affect downward gaze. Few affect downward gaze. These effects can range in severity from a complete lack of voluntary eye movement to mild impairments in speed, accuracy or range of eye movement.
Damage to the abducens nucleus does not produce an isolated sixth nerve palsy, but rather a horizontal gaze palsy that affects both eyes simultaneously. The abducens nucleus contains two types of cells: motor neurons that control the lateral rectus muscle on the same side, and interneurons that cross the midline and connect to the contralateral ...
This produces ipsilateral horizontal gaze palsy and facial nerve palsy and contralateral hemiparesis, hemisensory loss, and internuclear ophthalmoplegia. [ citation needed ] Diagnosis