Conjugate gaze palsies are neurological disorders affecting the ability to move both eyes in the same direction.
These palsies can affect gaze in a horizontal, upward, or downward direction.
These palsies overlap with ophthalmoparesis and ophthalmoplegia.
Symptoms of conjugate gaze palsies include the impairment of gaze in various directions and different types of movement, depending on the type of gaze palsy.
Patients with a gaze palsy may be frequent movement of the head instead of the eyes.
An abnormality in the brain stem tissue, due to injury or disease, disrupts the transmission of signals from the brain to the eye.
Conjugate gaze palsies originate in the brain stem, usually the midbrain, or pons.
Causes of such lesions include: stroke, or conditions such as Koerber-Salus-Elschnig syndrome, Progressive supranuclear palsy, Olivopontocerebellar syndrome, or Niemann-Pick Disease, Type C.
The specific location of the lesion determines the type of palsy.
Lesions in the abducens nucleus cause nonselective horizontal gaze palsies
Cranial nerve VI goes to the lateral rectus muscle, which controls eye movement horizontally away from the midline of the body.
The cranial nerve VI also has interneurons connecting to the medial rectus, which controls horizontal eye movement towards from the midline of the body.
Since the lateral rectus controls movement away from the center of the body.
The abducens nucleus disrupts the pathways controlling outward movements, not allowing the right eye to move right and the left eye to move left.
Nerve VI has the longest subarachnoid distance to its target tissue, making it susceptible to lesions.
Lesions anywhere in the abducens nucleus, cranial nerve VI neurons, or interneurons can affect eye movement towards the side of the lesion.
Lesions on both sides of the abducens nucleus can cause a total loss of horizontal eye movement.
Horizontal saccadic palsy is another type of gaze palsy associated with quick involuntary eye movements.
The paramedian pontine reticular formation in the pons is responsible for saccadic movement.
Diagnosed by demonstrating inability to move both eyes in one direction.
Conjugate gaze palsies can be classified into palsies affecting horizontal gaze and vertical gaze.
Horizontal gaze palsies are generally caused by a lesion in the brain stem and connecting nerves.
Horizontal gaze palsies affect gaze of both eyes either toward or away from the midline of the body.
Vertical gaze palsies affect movement of one or both eyes either in upward direction, up and down direction, or more rarely only downward direction.
There is no treatment of conjugate gaze palsy per se, but the disease or condition causing the gaze palsy must be treated.
Some of the conditions such as Progressive supra nuclear palsy are not curable.
Stroke victims with conjugate gaze palsies may be treated with fibrinolytic therapy if the patent presents early enough, or with a surgical procedure for other cases.
The prognosis depends on the nature of the lesion, recovery may happen rapidly or never.