may deviate ipsilateral to the side of the lesion because of a relative increase in input from the unaffected FEF on the opposite side of the brain.

Transient and conjugate downward or upward ocular deviation may occur in healthy newborns. In these cases, vertical doll’s head maneuver can move the eyes out of their tonically held position. Tonic downgaze in premature newborns, however, can be associated with serious neurologic disease, especially when intraventricular hemorrhage expands the third ventricle and presses on the pretectum. Tonic deviation of the eyes combined with retraction of the eyelids is the setting sun sign; it is primarily observed in children as part of dorsal midbrain syndrome (Parinaud syndrome). Conjugate paresis of upgaze is an associated finding, and in these cases, the doll’s head maneuver cannot induce upward movements of the eyes.

Oculogyric crisis is a tonic upward eye-movement deviation, sometimes directed toward the right or left, that does not disrupt a patient’s ability to move the eyes within the involved area. Patients find it difficult to direct their eyes downward. This disorder primarily is found as an idiosyncratic reaction to neuroleptic drugs, especially the higher-potency antipsychotic drugs like haloperidol and fluphenazine, as well as antiemetics such as metoclopramide, which are strong dopaminergic-blocking drugs. These drugs alter the supranuclear influences onto the ocular motoneurons and thus create a tonic deviation of the eyes. The crisis may persist for hours if not treated. In the early 1900s, patients with postencephalitic parkinsonism often experienced oculogyric crisis, but this syndrome is not seen in the modern era. Very occasionally, patients with Wilson disease may have an oculogyric crisis. Administration of anticholinergic drugs (such as prochlorperazine) promptly stops the eye deviation.

Caplan LR. “Top of the basilar” syndrome. Neurology. 1980;30(1):72–79.

Keane JR. The pretectal syndrome: 206 patients. Neurology. 1990;40(4):684–690.

Pursuit Dysfunction

Two main types of pursuit dysfunction occur: subnormal gain and poor initiation. Subnormal gain is the more common; it is typically observed in older patients without other definable neurologic problems or secondary to use of a wide range of medications. The subnormal gain results in eye movements that trail the target (ie, the motor output is not commensurate with the speed of the moving target), which prompts initiation of catch-up saccades to maintain visual fixation. (This combination of too-slow pursuit movements with interposed saccades is also called cogwheel, or saccadic, pursuit.) With age, reduced gain decreases the smoothness of smooth pursuit, although frankly saccadic pursuit is pathologic. Deficient ability to initiate smooth pursuit eye movements is associated with relatively large lateralizing lesions of the posterior hemisphere or frontal lobes or of their underlying white matter. In such cases, the pursuit deficit is to the side of the lesion (and can be observed with use of the OKN drum). Pursuit movements made into a blind hemifield are often poor or absent. Smooth pursuit deficits are usually present in both horizontal and vertical planes, although the vertical plane may be involved selectively in patients who have bilateral internuclear ophthalmoplegia or PSP.

Vergence Disorders

Although vergence disorders are common, their diagnosis can be challenging because convergence

depends heavily on patient effort. These disorders most commonly are classified as convergence insufficiency, convergence spasm, or divergence insufficiency. Unlike other supranuclear disorders, vergence disorders usually result in diplopic symptoms.

Convergence insufficiency

Convergence insufficiency is a common cause of diplopia during near point tasks in patients older than 50 years and is often an isolated finding. In the absence of other neurologic symptoms, further workup is not needed. Nonetheless, many neurologic conditions are associated with convergence insufficiency, most notably extrapyramidal disorders such as Parkinson disease and PSP. Lesions of the pretectal area may also be associated with convergence insufficiency; however, such lesions are typically accompanied by other features of the dorsal midbrain syndrome. Lesions of the midbrain (within the mesencephalic reticular formation and just dorsal to the third nerve nuclei) may cause convergence insufficiency with normal third nerve function. Closed head trauma may also nonspecifically produce convergence insufficiency.

Convergence spasm

Excessive convergence tone is typically observed in younger patients who have an inborn convergence abnormality (ie, a high accommodative convergence to accommodation [AC/A] ratio, which produces an excessive amount of convergence for a given amount of accommodation) that manifests as an early-onset esotropia (see BCSC Section 6, Pediatric Ophthalmology and Strabismus). Isolated intermittent convergence spasm is almost never related to organic disease. However, convergence spasm associated with other abnormalities, especially convergence-retraction nystagmus and reduced conjugate upgaze (as in the dorsal midbrain syndrome), indicates organic neurologic impairment. Acquired convergence spasm also can be observed in patients with lesions at the junction of the diencephalon and mesencephalon (eg, thalamic esotropia due to thalamic hemorrhage) and lower brainstem and cerebellar disorders in association with other signs and symptoms related to lesion location (eg, Wernicke encephalopathy, Arnold-Chiari malformation, multiple sclerosis).

Divergence insufficiency

Divergence insufficiency is an acquired disorder that produces comitant esodeviation that is greater at distance than at near. This disorder is usually benign, but it can be confused with bilateral sixth nerve palsy, although sixth nerve palsy is associated with abnormal speed and amplitude of abducting saccades. Divergence paralysis also may occur as an incipient manifestation of a unilateral sixth nerve palsy or appear during the resolving phase of a sixth nerve palsy; it has also been reported in association with altered intracranial pressure, midbrain tumors, craniocervical junction lesions, or spinocerebellar ataxia. When it is an isolated neurologic finding, divergence insufficiency does not require further workup, although patients should be observed for development of other neurologic signs.

Jacobson DM. Divergence insufficiency revisited: natural history of idiopathic cases and neurologic associations. Arch Ophthalmol. 2000;118(9):1237–1241.