See-saw nystagmus is an unusual but dramatic type of nystagmus that has both vertical and torsional components. The name derives from the action of the familiar playground device. If 2 eyes were placed on a see-saw, one at either end, they would “roll down the plank” as the see-saw rose, with the high eye intorting and the low eye extorting. As the direction of the see-saw changed, so would that of the eye movement. Thus, the eyes make alternating movements of elevation and intorsion followed by depression and extorsion.

This type of nystagmus is often associated with a lesion in the rostral midbrain or the suprasellar area. In children, the most likely associated intracranial tumor is a craniopharyngioma. Confrontation visual fields may elicit a bitemporal defect. Neuroradiologic evaluation is necessary. A congenital form of see-saw nystagmus is seen with complete or partial achiasma.

Vertical nystagmus

Vertical nystagmus is uncommon. Congenital vertical nystagmus is sometimes seen in infants with inherited retinal dystrophies. Downbeat nystagmus, one form of vertical nystagmus, may occur as a congenital disorder associated with good vision and normal neurologic findings. This jerk nystagmus has a downward fast component and often a null point in upgaze. More commonly, vertical nystagmus is acquired and secondary to structural abnormalities such as the Arnold-Chiari malformation. Medications such as codeine, lithium, tranquilizers, and anticonvulsants may also cause this condition. Neurologic evaluation is usually indicated in patients with acquired vertical nystagmus.

Monocular nystagmus

Monocular nystagmus has been reported to occur in severely amblyopic and blind eyes (HeimannBielschowsky phenomenon). The oscillations are pendular, chiefly vertical, slow, variable in amplitude, and irregular in frequency.

Nystagmus-Like Disorders

Convergence-Retraction Nystagmus

Convergence-retraction nystagmus (induced convergence-retraction) is part of the dorsal midbrain syndrome, associated with paralysis of upward gaze, defective convergence, eyelid retraction, and pupillary light–near dissociation. In the pediatric age group, convergence-retraction nystagmus is commonly secondary to congenital aqueductal stenosis or a pinealoma. The nystagmus is best elicited on attempted upgaze saccades (eg, by asking the patient to track a downward-rotating OKN drum). Co-contraction of all horizontal extraocular muscles occurs, resulting in retraction of the globe. In addition, the medial rectus muscles overpower the lateral rectus muscles, causing the eyes to converge on attempted upgaze (hence the term convergence-retraction). However, voluntary convergence is minimal. The abnormal eye movements in convergence-retraction nystagmus are actually saccades. Therefore, convergence-retraction nystagmus is not a true nystagmus.

Opsoclonus

Opsoclonus is an eye movement disorder, not a true nystagmus. It consists of involuntary saccades that are rapid and multidirectional, often accompanied by somatic dyskinesias. Opsoclonus can occur intermittently and often presents as eye movements with very high frequency and large amplitude. Causes of opsoclonus in children include acute postinfectious cerebellar ataxia, viral encephalitis, and a paraneoplastic manifestation of neuroblastoma.