Patient Presentation
A 4-month-old male came to clinic for his well child check. His parents reported that he was doing well. He was breastfeeding vigorously and was smiling and trying to roll over. The past medical history was non-contributory. The family history was negative for any neurological, ophthalmological or genetic problems.

The pertinent physical exam showed a smiley baby with growth parameters in the 10-50% and trending appropriately. Eye examination revealed pupils that were equal, round and reactive to light, normal red reflexes bilaterally. However, there was bilateral, intermittent, lateral, nystagmus that varied in amplitude. During the examination the nystagmus wouldn’t always occur. His head showed some very mild positional plagiocephaly on the right occiput without changes to the ear or face. There was a mild right sternocleidomastoid muscle torticollis as well. The neurological examination was normal. The diagnosis of nystagmus was made. With further questioning the parents said that a family member had noted it the previous week, but that they really didn’t think much of it as he overall seemed well. They denied any other unusual movements or posturing and no seizures. “His head is always turned toward the left and he always lays on that side,” his mother offered. The pediatrician discussed the findings and instructed the family how to improve the positioning for his plagiocephaly as well as starting to do some stretching exercises of his neck. An ophthalmologist examined the infant within the week and found bilateral, horizontal and vertical nystagmus that was intermittent and of low amplitude. Electroretinography was negative. He also noted head bobbing in the infant and the torticollis, and

the diagnosis of spasmus nutans was made. He ordered a head magnetic resonance imaging study that was negative. Over the next few weeks, the torticollis improved but needed more intensive physical therapy without cranial banding. At his 9 month examination, the patient still had intermittent nystagmus and head bobbing.

Discussion
Nystagmus is periodic eye movement that is involuntary where there is a slow drift of fixation. The slow drift can be followed by a fast saccade back to fixation. The pathological movement is the slow phase, but nystagmus is described by the fast phase (i.e. horizontal nystagmus, vertical nystagmus).

Spasmus nutans (SN) is a movement disorder that is rare. The classic triad includes nystagmus, head bobbing or titubation, and torticollis, with these problems being in the absence of any ophthalmological or neurological condition. Onset is in the first year of life but ranges from 6-36 months. Time to resolution is sometimes stated as 1-2 years, but others disagree citing longer time frames. There is no harm to visual acuity.

• The SN nystagmus is usually intermittent, high frequency of small or low amplitude. It is “…variably disconjugate or disjunctive, greater in the abducting eye, and may have a vertical component.” Amblyopia and strabismus may coexist with SN.
• The head bobbing is irregular may have both vertical and horizontal components.
• Torticollis occurs as the child moves the head to try to obtain better visual acuity. The differential diagnosis of torticollis can be reviewed here.

The differential diagnosis of SN includes ophthalmic problems such as congenital (infantile) nystagmus (a review can be found here), refractive disorders and retinal diseases, and problems of the central nervous system such as optic chiasm gliomas, diencephalic tumors, brain malformations, opsoclonus-myoclous, and bobble-head doll syndrome.

Learning Point
As SN is rare, reports of complications are even rarer but most concerning are potential underlying brain tumors particularly optic chiasm gliomas or neurological abnormalities. Rates of optic gliomas have been reported in small studies from 0% to 9%.

In a 2017 study of 40 patients with SN who had magnetic resonance imaging, 25 patients had normal findings, none had optic nerve gliomas or other masses, and 2 had optic nerve hypoplasia. Other patients, including many who were otherwise healthy, had a variety of imaging findings which could or could not be clinically significant. The authors concluded that “…the risk of optic gliomas in children without other neurological deficits or signs concerning for intracranial mass lesions is very low.”

In a 2018 long-term followup study of 22 patients, 17 had neuroimaging and all 17 were negative for any space occupying lesions, and 1 “…had findings suggesting hydrocephalus….”

In this same 2018 long-term followup study, their patients had an average age of SN onset of 9.7 months (range 3-33 months ) and followup of 62.6 months (range 7-156). Nystagmus “…resolved in 4 [patients], from 2 to 49 months after presentation (mean 20 months), at ages ranging from 11-54 months (mean 30 months).” Head bobbing “…resolved during follow-up ranging from 1 to 49 months (mean 20 months), at ages ranging form 10 to 54 months (mean 27 months).” Torticollis improved in only 1 of 7 children, 39 months after presentation at the age of 51 months. During the study, no patients developed additional problems such as myopia, photophobia, night blindness or specific retinal pathology. With this data, the authors state that they advise families “…that many children do well, assuming normal imaging, but that nystagmus, torticollis and even titubations may persist.”

Questions for Further Discussion
1. What causes strabismus?
2. What are common movement disorders in children? A review can be found here

Related Cases

Disease: Spasmus Nutans | Eye Movement Disorders

Symptom/Presentation: Nystagmus

Specialty: Ophthalmology | Neurology / Neurosurgery |

Age: Infant

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for this topic: Eye Movement Problems

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Delorme C, Gras D, Roze E. Spasmus Nutans: More Than Meets the Eye. Pediatr Neurol. 2015 Oct;53(4):367-8.

Bowen M, Peragallo JH, Kralik SF, Poretti A, Huisman TAGM, Soares BP. Magnetic resonance imaging findings in children with spasmus nutans. J AAPOS. 2017 Apr;21(2):127-130.

Parikh RN, Simon JW, Zobal-Ratner JL, Barry GP. Long-Term Follow-up of Spasmus Nutans. J Binocul Vis Ocul Motil. 2018 Oct-Dec;68(4):137-139.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa