The author reviews the various manifestations and causes of vertical gaze palsy. These can affect upgaze, downgaze, or both, usually affecting saccades primarily. When acquired, they imply lesions of supranuclear vertical gaze structures in the rostral midbrain and can be associated with other signs of the pretectal (Parinaud) syndrome. Degenerative disorders like progressive supranuclear palsy and metabolic disorders like Niemann-Pick type C are other causes of vertical gaze palsy.
| || |
• Vertical gaze palsies are due to damage to pre-motor structures in the midbrain, namely the rostral interstitial nucleus of the medial longitudinal fasciculus and the interstitial nuclear of Cajal.
| || |
• Vertical gaze palsies can involve upgaze, downgaze, or both.
| || |
• Parkinsonian conditions with vertical gaze palsies are most often due to tauopathies, such as progressive supranuclear palsy and corticobasal degeneration.
| || |
• Several genetic defects can cause cerebellar ataxia with vertical gaze palsies, chief of which is Niemann Pick type C disease.
Historical note and terminology
The term “gaze palsy” is best restricted to deficits in conjugate eye movements that affect both eyes. Thus, strictly unilateral problems such as palsies of cranial nerves III, IV, or VI are not gaze palsies, even though they do affect gaze. Likewise, impairments in vergence control, such as convergence or divergence insufficiency, are not gaze palsies, as they do not involve conjugate eye movements.
A fundamental distinction is between vertical and horizontal gaze palsies. Most gaze palsies affect 1 direction in 1 plane of eye movement only, reflecting the separation of the prenuclear control systems for vertical and horizontal eye movement. Reduction of eye movements in all planes is best termed “generalized ophthalmoparesis” and typically has an etiology distinct from those causing gaze palsies. These reductions are most commonly myopathic, occurring with mitochondrial disorders (chronic progressive external ophthalmoplegia, Kearns-Sayre syndrome, MELAS), muscular dystrophies (myotonic dystrophy, oculopharyngeal dystrophy, congenital fibrosis), myasthenia gravis, or thyroid eye disease, among others.
The term “gaze palsy” requires further elaboration. There are many different types of conjugate eye movements, including saccades, pursuit, optokinetic, and vestibulo-ocular responses. The anatomic systems that control these diverge and converge at various levels, and it is possible for some lesions to impair some eye movement systems and spare others. Hence, a left saccadic palsy is a selective gaze palsy affecting only leftward saccades but not leftward pursuit or vestibulo-ocular response. A palsy affecting all types of eye movements should be designated as a nonselective gaze palsy. Most vertical gaze palsies are selective in nature.
In contrast, the terms “partial” or “complete” when applied to gaze palsy indicate whether some motion across midline in the paretic direction is present.