What Are the Clinical Features of Idiopathic Infantile Nystagmus?

Patient Presentation
A 7-month-old female came to clinic with an upper respiratory illness and fever to 100.8°. The resident was concerned that the infant may also have acute otitis media. During the attending physican’s pertinent physical exam he noted right away that the patient had abnormal eye movements. He wasn’t sure exactly what the movement was so he carefully looked at the child’s eyes while examining the rest of the patient. The mother noticed that he was looking at her daughter’s eyes and offered, “She has congenital nystagmus.” “Oh, that explains it,” he remarked. The mother then told the physicians that the child was noted around the time of birth to have abnormal eye movements. “We thought she was blind, but we see the ophthalmologist who says she sees,” the mother commented. She continued, “So far she doesn’t seem to have a head turn and they say she may or may not get better with the movements of her eyes.”

The diagnosis of an upper respiratory infection without acute otitis media and congenital nystagmus was made. After the visit, the resident physician said that he had seen the eye movements but had forgotten to mention them during his presentation to the attending. The attending said that he didn’t know much about congenital nystagmus and would have to review it.

Discussion
Nystagmus is “…an involuntary, periodic eye movement caused by a slow drift of fixation. This drift may be followed by a fast refixation saccade…or a slow movement back to fixation….” The pathological movement is the slow phase, but nystagmus is described by the fast phase (i.e. horizontal nystagmus, vertical nystagmus). Both eyes usually move synchronously. Patients may turn or tilt their heads to improve visual acuity.

Nystagmus is categorized into 3 groupings – physiologic such as gaze evoked, caloric or opto-kinetic nystagmus, acquired such as neurological or ophthalmological diseases, or infantile nystagmus. Infantile is sometimes referred to as congenital because the onset occurs at birth or during infancy.

Full opthalmological evaluation of nystagmus or other abnormal eyes movements is appropriate as is the necessary followup. Warning signs include neurological signs such as nausea, vertigo or any focal defects, onset age after 4 months, asymmetric nystagmus, focal ophthalmological signs such as papilledema or pupillary defects, oscillopsia (i.e. visual field objects appear to oscillate), nystagmus that is asymmetric, and preserved opto-kinetic nystagmus (i.e. nystagmus induced by looking at objects moving across the visual field). These signs are more consistent with an acquired nystagmus and not infantile nystagmus.

Learning Point
Prevalence of infantile nystagmus is difficult to ascertain but studies have estimated it to be 1:1000 – 1:3000 in some studies and up to 17:10,000 in another. Infantile nystagmus has 4 types: idiopathic (see below), ocular nystagmus associated with albinism and ophthalmological malformations, latent type nystagmus occurring with esotropia, and spasmus nutans that appears later (6-12 months) has head nodding and disappears after 1-2 years.

Idiopathic infantile nystagmus presents in the first 6 months of life, but usually in the first 3-4 months. It has a low to medium frequency often horizontal in position but may have occasional torsional or vertical components. Its character may change with gaze position and increase with fixation and reading small print. A null gaze point may also be present. A null gaze point is an eye position where the nystagmus is much improved. Patients will often tilt or turn their head to maintain their eyes in this position to improve their visual acuity. Idiopathic infantile nystagmus does not abate but generally has improved amplitude over the first couple of years.

The genetics of infantile idiopathic nystagmus has mainly autosomal dominant and X-linked forms. Although it cannot be cured, treatment with magnifying visual aids and eye muscle surgery (for head posture or null gaze point improvement) may be helpful.

Questions for Further Discussion
1. Describe how to peform a screening eye examination on an infant?
2. What are the indications for evaluation by an ophthalmologist for an infant?
3. What is the difference between nystagmus and ocular motor apraxia? Click here
4. What are indications for neuroimaging with nystagmus?

Related Cases

Disease: Infantile Nystagmus | Eye Movement Disorders

Symptom/Presentation: Nystagmus

Specialty: Ophthalmology

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, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Eye Movement Disorders.

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.

Abel LA. Infantile nystagmus: current concepts in diagnosis and management. Clin Exp Optom. 2006 Mar;89(2):57-65.

Felius J, Fu VL, Birch EE, Hertle RW, Jost RM, Subramanian V. Quantifying nystagmus in infants and young children: relation between foveation and visual acuity deficit. Invest Ophthalmol Vis Sci. 2011 Nov 7;52(12):8724-31.

Ehrt O. Infantile and acquired nystagmus in childhood. Eur J Paediatr Neurol. 2012 Nov;16(6):567-72.

ACGME Competencies Highlighted by Case