Spasmus nutans syndrome
Spasmus nutans syndrome (spasmus nutans) is an idiopathic acquired nystagmus that manifests during the first 2 years of life, presenting as a triad of generally small-amplitude, high-frequency (“shimmering”), dysconjugate nystagmus; head nodding; and torticollis. The nystagmus is binocular but often asymmetric, sometimes appearing to be monocular. The plane of the nystagmus can be horizontal, vertical, or torsional; the nystagmus can vary with gaze position, and it is occasionally intermittent. The head nodding and torticollis appear to be compensatory movements that maximize vision. The natural history of spasmus nutans syndrome is diminution of the abnormal head and eye movements by 3–4 years of age. Spasmus nutans syndrome is a benign disorder in most cases, but there is a high incidence of associated strabismus, amblyopia, and developmental delay.
Spasmus nutans–like nystagmus has been seen with chiasmal or suprachiasmal tumors and retinal dystrophies such as congenital stationary night blindness. Neuroradiologic investigation is warranted when there is any evidence of optic nerve dysfunction (eg, disc pallor, relative afferent pupillary defect) or any sign of neurologic abnormality. Because subtle optic disc pallor and relative afferent pupillary defects can be difficult to assess in children, some investigators prefer neuroimaging for all young children with nystagmus resembling spasmus nutans syndrome.
See-saw nystagmus is an unusual but dramatic type of dysconjugate nystagmus that has both vertical and torsional components. If the 2 eyes are envisioned as being placed on an imaginary see-saw, one at either end, they “roll down the plank” as one end of the see-saw rises, with the high eye intorting and the low eye extorting. As the direction of the see-saw changes, so does that of the eye movement. Thus, the eyes make alternating movements of elevation and intorsion, followed by depression and extorsion (Video 13-4).
Courtesy of Agnes M.F. Wong, MD, PhD.
This type of nystagmus is often associated with rostral midbrain or suprasellar lesions, most often craniopharyngioma in children. Confrontation visual field testing may elicit a bitemporal defect. Neuroradiologic evaluation is necessary. A congenital form of see-saw nystagmus can be seen in disorders of decussation, such as Joubert syndrome.
Vertical nystagmus is uncommon. Congenital vertical nystagmus is sometimes seen in infants with inherited retinal dystrophies. Downbeat nystagmus (upward slow phase with downward fast phase) (Video 13-5), which often features a null point in upgaze, may occur as a congenital disorder associated with good vision and normal neurologic findings. More commonly, vertical nystagmus is acquired, secondary to structural abnormalities such as Arnold-Chiari malformations or use of medications such as codeine, lithium, anxiolytics, and anticonvulsants. Neurologic evaluation is usually indicated in patients with unexplained acquired vertical nystagmus.
Courtesy of Janet C. Rucker, MD.
Monocular nystagmus has been reported to occur in severely amblyopic or blind eyes (Heimann-Bielschowsky phenomenon). The oscillations are pendular, chiefly vertical, slow, variable in amplitude, and irregular in frequency.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.