Spasmus Nutans Syndrome
Spasmus nutans syndrome is a childhood nystagmus characterized by asymmetric, small-amplitude, high-frequency, “shimmering” eye movements, often accompanied by head nodding and an abnormal head posture (torticollis). The nystagmus may be dissociated (sometimes even monocular), and the amplitude and phase relationships of the eye movements may vary between the eyes over the course of a few seconds. The shimmering eye movements are often variable or intermittent; may occur in the horizontal, vertical, or oblique plane; and may increase in the abducted eye during lateral gaze. Head nodding, torticollis, or both occur in approximately 60% of patients and appear to damp the nystagmus and improve vision.
Spasmus nutans syndrome is typically acquired in the first year of life and spontaneously improves 2–8 years later. Secondary amblyopia and strabismus may occur in the more involved eye. The syndrome is sometimes familial and is associated with African American ethnicity, Hispanic ethnicity, and low socioeconomic status.
In general, spasmus nutans syndrome is distinguished from INS by the asymmetric or monocular, high-frequency, small-amplitude, shimmering, multiplanar, variable nature of the nystagmus. In contrast, INS consists of larger amplitude, lower frequency, bilateral, conjugate, symmetric, horizontal, constant ocular movements.
The etiology of spasmus nutans syndrome is unknown. Chiasmal/suprachiasmal tumors (eg, optic pathway gliomas), retinal dystrophies (eg, congenital stationary night blindness), and neurodegenerative disorders (eg, Pelizaeus-Merzbacher disease or Leigh disease) may result in an identical nystagmus. Therefore, neuroimaging is indicated for patients with presumed spasmus nutans syndrome to exclude a glioma of the anterior visual pathway or other parasellar or hypothalamic tumors. An electroretinogram should be obtained if the patient shows signs of a retinal dystrophy (eg, progressive visual loss, photophobia, nyctalopia, eye pressing, paradoxical pupils, or high refractive error). Progressive developmental delay requires an evaluation for neurodegenerative disease.
Patients with spasmus nutans syndrome should be monitored and treated for any associated amblyopia and strabismus. As noted earlier, the abnormal eye and head movements typically disappear after several years (usually by the end of the first decade of life). Lack of resolution or development of other neurologic problems should prompt appropriate evaluation, including neuroimaging.
Kiblinger GD, Wallace BS, Hines M, Siatkowski RM. Spasmus nutans-like nystagmus is often associated with underlying ocular, intracranial, or systemic abnormalities. J Neuroophthalmol. 2007:27(2):118–122.
Lambert SR, Newman NJ. Retinal disease masquerading as spasmus nutans. Neurology. 1993; 43(8):1607–1609.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.