Conjugate gaze palsies or forced conjugate gaze may result from disease of the cerebrum, diencephalon, brain stem, cerebellum, or peripheral labyrinth apparatus.
Conjugate gaze palsies do not cause double vision. Patients usually do not know there is anything amiss with the way their eyes move in tandem. A decreased level of consciousness frequently accompanies a gaze palsy or forced conjugate gaze of acute onset.
When a patient has a conjugate gaze palsy to the left, he cannot look to the left of the midline with either eye but he does not have paresis of the left lateral rectus muscle or of the right medial rectus.
There is more than one way to demonstrate a gaze palsy, and the method is important; that is, if the patient cannot look to the left when asked, can he pursue an object moving to his left, or can he fix on a stationary object in front of him and keep looking at it as his chin is rotated to his right shoulder? Will his eyes move conjugately with stimulation of the labyrinth with hot or cold water? (See the section on eighth cranial nerve examination in Chapter 9.) Do his eyes respond normally to doll's eye testing (see below)? Therefore, a gaze palsy may be voluntary, pursuit, or reflex with different anatomical implications (supratentorial, brain stem, or peripheral).
Forced conjugate deviations are usually caused by acute lesions in seriously ill and often stuporous patients. All the centers concerned with conjugate gaze have opposing centers that have the opposite function. If the right cerebral hemisphere center concerned with conjugate gaze to the left is suddenly destroyed by a hemorrhage, the eyes will be forced to the right temporarily by the now unopposed left hemisphere center. Forced conjugate gaze is the result of either destruction or irritation of a nervous system gaze center or of a labyrinth lesion.
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