Introduction:
A gaze palsy refers to an abnormality in eye movement in which the two eyes move together but have limited movement in one direction. For example, malfunctioning cortical gaze centers can lead to supranuclear gaze palsy, whereas malfunctioning the brainstem gaze center can lead to nuclear gaze palsy.
Vertical gaze palsy includes Parinaud's syndrome, progressive supranuclear palsy, and skew deviation. Paralysis of the upward vertical gaze palsy is the most common vertical gaze palsy, followed by paralysis of both the upward and downward gaze, and finally, paralysis of downward gaze alone. Failure of upgaze is caused by an upper brainstem lesion such as a supratentorial mass or a brainstem tumor. When the pupillary convergence reflex fails in addition, this is called Parinaud's syndrome.
The syndrome occurs in dorsal midbrain lesion that usually involves the rostral interstitial nucleus and the third nuclear complex. In addition, convergence or retraction nystagmus can occur. Defective upgaze also develops in certain degenerative disorders, such as progressive supranuclear palsy.
It is a progressive neurodegenerative disorder that affects the elderly. It initially impairs the downgaze, then the upgaze, followed by loss of horizontal, saccadic, and pursuit eye movements. Individuals may also develop pseudobulbar palsy, parkinsonism, and dementia. Some impairment of upgaze may also occur as a result of normal aging.
Three pathways control eye movement:
-
The supranuclear pathway from the brain's cortex to the oculomotor nuclei in the brainstem.
-
Ocular motor nuclei.
-
The intranuclear pathway from the oculomotor nuclei to the peripheral nerve, neuromuscular junction, and extraocular muscles.
What Are the Causes of Vertical Gaze Palsy?
Vertical gaze palsy can occur from a variety of causes, such as
-
Tumors of the quadrigeminal region, such as pineal germinoma or teratoma, tectal glioma, pineocytoma, pineoblastoma,
-
Hydrocephalus aqueductal stenosis will lead to dilatation of the third ventricle and suprapineal recess enlargement with pressure on the posterior commissure.
-
Drugs such as Carbamazepine, barbiturates, and neuroleptic agents.
-
Metabolic disorders include Niemann Pick syndrome, maple syrup urine diseases, Tay Sachs disease, kernicterus, and Wilson's disease.
-
Degenerative diseases such as Huntington's, diffuse Lewy body disease, basal cortical degeneration, hereditary spastic ataxia, parkinsonism, and progressive supranuclear palsy.
-
Infectious diseases include tuberculosis, syphilis, encephalitis, and Whipple disease.
-
Others - Mesencephalic cleft, hypoxia, trauma, and multiple sclerosis.
What Is the Pathophysiology of Vertical Gaze?
Three main structures control the vertical gaze center. They are
-
Rostral Interstitial Nucleus of the Medial Longitudinal Fasciculus: It is situated in the midbrain and aids in vertical and torsional saccades. The bilateral rostral interstitial nucleus of medial longitudinal fasciculus structures is connected dorsally through the posterior commissure. It normally has bilateral effects on the elevator muscles, like the superior rectus and the inferior oblique muscles, and unilateral effects on depressor muscles, such as the inferior rectus and the superior oblique muscles, thus lesions to the rostral interstitial nucleus will have more effect on downward than up saccades.
-
Interstitial Nucleus of Cajal (INC): It is situated in the midbrain and aids in coordinating all vertical eye movements except saccades. Unilateral lesions mostly result in an ocular tilt reaction and defects in vertical pursuit and gaze holding. The ocular tilt reaction has a characteristic presentation as ipsilateral hypertropia and intorsion, along with contralateral extorsion and head tilt. Bilateral lesions may cause reduced range in all vertical eye movements except saccades.
-
Posterior Commissure: It is situated on the dorsal aspect of the cerebral aqueduct and is involved with all vertical eye movements, specifically upward eye movement. The upward gaze fibers cross at the posterior commissure; therefore, single lesions in this location can produce upgaze vertical gaze palsy. Lesions eventually lead to impairment of all vertical eye movements, especially upward, with loss of vertical gaze-holding function.
What Are the Signs and Symptoms of Vertical Gaze Palsy?
Signs and symptoms include
-
Blurred vision.
-
Decreased visual acuity.
-
Ocillopsia or bouncing images.
-
Dizziness.
-
Postural imbalance.
-
Gait disturbances.
-
Ataxia.
-
Increased chances of fall.
Vertical gaze palsy usually selectively affects saccades. Upgaze palsy is the most common, combined upgaze and downgaze, followed by downgaze palsy. Suppose the rostral interstitial nucleus of the medial longitudinal fasciculus is affected. Other signs and symptoms include ocular motor signs of third nerve palsies, including wall-eyed bilateral internuclear ophthalmoplegia, skew deviation, and impaired convergence. If there is thalamic damage, behavioral disturbances may be observed, like hemineglect, slowness of thoughts, akinetic mutism, and subcortical demented states with apathy. If the posterior commissure is affected, pathologic lid retraction while looking straight ahead (Collier tucked lid sign) may be present along with mid-dilated pupils that show a lesser reaction to light than to near stimulus (light-near dissociation). Attempted upward saccades producing convergence-retraction nystagmus may also be present.
What Is the Diagnosis for Vertical Gaze Palsy?
The diagnosis of vertical gaze palsy is based on the following:
-
Cerebrospinal Fluid (CSF) Study: It reveals a lymphocytic pleocytosis with normal protein and sugar. CSF oligoclonal bands were negative.
-
Magnetic Resonance Imaging (MRI): It shows areas of asymmetrical hyperintensities involving bilateral parietal areas with the involvement of the corpus callosum. It also shows areas of demyelination in the brainstem.
What Is the Management of Vertical Gaze Palsy?
Vertical gaze palsy is usually managed by treating the underlying causes. Vascular causes may be managed with antiplatelet or anticoagulant administration. Niemann-pick disease may have an improved prognosis with Miglustat.
Parkinson’s disease may be treated with Levodopa, which helps improve the ophthalmic manifestation, like saccadic accuracy. In addition, surgical management may be done in cases of neoplasms or refractory symptoms.
Diplopia and other ophthalmic symptoms are treated conservatively and may involve refractive correction, a Fresnel prism, or ground-in prism glasses. In conjunction with physical and occupational therapy, vision rehabilitation therapies may be beneficial in some cases. Single-vision glasses and readers should be used in patients with downgaze palsy who cannot use bifocal or progressive add lenses effectively.
Conclusion
Patient with vertical gaze palsy requires thorough clinical neuro-ophthalmological examination and neuroimaging to establish the cause and investigate the location of the lesion. Ruling out the etiology to reach a diagnosis is always helpful in such cases, along with a well-detailed history taking, clinical findings, and investigations. MRI examination is always helpful in diagnosing the underlying demyelination.
