Nystagmus can be easily identified in patients, but differentiating between dangerous and benign types can be challenging. Here are a few pearls to aid in your decision to order neuroimaging or other tests when you encounter nystagmus.
1. Characterize the nystagmus.
Taking a video of the nystagmus and watching it in slow motion can be helpful. Watch the video for at least two minutes because it’s important to rule out periodic alternating nystagmus.
Otherwise, is it intermittent or constant? High or low frequency? Large or small amplitude? Horizontal, vertical, or torsional (rotational)? Do the eyes move together or separately (conjugate or disconjugate)? Is the movement pendular (slow phases in both directions) or jerky (slow phase in one direction and fast phase in opposite direction)? Or is it a saccadic intrusion (fast movements only)? Do these characteristics change with different gaze positions?
Characterizing the nystagmus may enable localization. For example, seesaw nystagmus, which comprises elevation and incyclotorsion of one eye and depression and excyclotorsion of the other eye, localizes the pathology to the parasellar region and warrants neuroimaging.
2. Determine chronicity.
Longstanding congenital nystagmus does not typically require further workup. If a patient does not recall when the nystagmus began, look for a face turn that places the eyes in a null zone where they are moving the slowest (and maximizes the vision for the patient). If there are old photos that show the patient making the same face turn, it suggests that the nystagmus is longstanding. Conversely, an important sign that nystagmus is acquired is the presence of oscillopsia.
3. Search for a sensory issue.
Nystagmus that can be explained by poor vision with a known ocular cause requires further investigation only if indicated by the underlying sensory problem. Sensory nystagmus is usually congenital, but it can be acquired. In children, look for common causes of sensory nystagmus, such as optic nerve hypoplasia and ocular or oculocutaneous albinism (see photo below).
4. Identify associated ocular motor abnormalities.
Nystagmus caused by lesions in the brain stem or cerebellum may be accompanied by certain types of strabismus, such as skew deviation, cranial nerve palsies or gaze palsies. In contrast, other forms of strabismus indicate a non-neurologic, congenital cause. For example, dissociated vertical deviation (DVD) and congenital esotropia are often associated with latent or manifest latent nystagmus.
5. Look at the palate.
Oculopalatal myoclonus is characterized by a vertical pendular nystagmus associated with rhythmic movements of the soft palate of the throat. This syndrome occurs as a late consequence of a lesion affecting the Guillain-Mollaret triangle, which consists of the red nucleus, inferior olivary nucleus and contralateral cerebellar dentate nucleus (the dentato-rubro-olivary pathway). In patients without a known history of damage in this region (most commonly stroke), neuroimaging is necessary.
6. Look for other neurologic symptoms.
The presence of nausea, vertigo, tinnitus and hearing loss suggest a peripheral vestibular problem. Recurrent sensory, motor, gait, and/or bowel or bladder incontinence may indicate a demyelinating process, such as multiple sclerosis. Unmanageable bouts of hiccups, nausea, and vomiting can be symptoms that the medulla is affected by neuromyelitis optica spectrum disorder (NMOSD). Ataxia and changes in mental status are associated with vertical nystagmus in Wernicke’s encephalopathy.
7. Ask about medications, tobacco and substance abuse.
Illicit drugs, alcohol and medications (lithium and anti-seizure medications in particular) are a common cause of nystagmus. Paraneoplastic syndromes may be associated with opsoclonus (a saccadic intrusion) or other forms of nystagmus. In adults, small-cell lung cancer is a frequent culprit, so getting a smoking history is important.
8. Special considerations in pediatric patients.
Children with genetic and metabolic disorders may show signs of nystagmus. New-onset strabismus, optic atrophy, developmental delay or regression, neurologic symptoms such as ataxia and/or positive family history should prompt neuroimaging.
Tumors in children also occur more commonly in the posterior fossa, which can lead to nystagmus when the brain stem or cerebellar is involved. Certain types of nystagmus are suspicious for neoplasms in children (e.g. convergence retraction "nystagmus" occurs in dorsal mid-brain syndrome, which frequently results from a tumor such as a germinoma, or tumor-related hydrocephalus).
Spasmus nutans, a high-frequency low-amplitude dissociated nystagmus that is associated with torticollis and head bobbing, is benign and resolves by the time a child reaches 3 to 4 years old. However, certain tumors, including optic pathway gliomas, may result in nystagmus that masquerades as spasmus nutans. Neuroimaging may be necessary for children with apparent spasmus nutans, especially those with atypical features.
Consider neuro-imaging or additional testing if:
- There is a vertical component
- The nystagmus is new
- There are any other accompanying neurological signs or symptoms like palate involvement, nausea, or vomiting
Ocular and oculocutaneous albinism are common causes of sensory nystagmus in children. A) Wide-angle fundus photograph of a child with ocular albinism demonstrates peripheral hypopigmentation and foveal hypoplasia, which may be difficult to appreciate on examination. B) Optical coherence tomography (OCT) confirms foveal hypoplasia, with absence of the normal foveal pit. Photo courtesy of Aaron Nagiel, MD, PhD
About the author: Melinda Chang, MD, is a member of the North American Neuro-Ophthalmology Society’s Young Neuro-Ophthalmologists Committee (YONO). She is a pediatric neuro-ophthalmologist at Children's Hospital Los Angeles and the University of Southern California Roski Eye Institute. She completed her ophthalmology residency, pediatric ophthalmology fellowship and neuro-ophthalmology fellowship at the Stein and Doheny Eye Institutes at the University of California, Los Angeles.
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