Samuel, an 8-week-old infant, presents to primary care with bilateral “shaky, jerky eyes.” The child had been developing normally but was observed by his mother to have “shaky, jerky eyes” when his eyes were opened.
Samuel was delivered via c-section at a gestational age of 38 weeks to multi-racial parents. His mother was of Asian descent, and his father was Dutch/German. There was no known family history of genetic disorders. He weighed 8 lbs 4 oz. The delivery was uncomplicated, and Samuel passed all his newborn screening tests. He had no signs of developmental delays and was adequately gaining weight after delivery.
When Samuel presented at 8 weeks, his vital signs were all within normal limits:
- Temperature: 98° F
- Weight: 15.7 lbs
- Pulse: 140 beats per minute
- Respiratory rate: 36 breaths per minute
- Head circumference: 38 cm
In general, he was alert, well-nourished, well-developed, and was in no acute distress. He cooed during examination and had a social smile. He became upset with the examination but was easily calmed by his parents.
Head: normocephalic, nontraumatic, anterior fontanelle was soft and flat
Eyes: pendular nystagmus bilaterally, red reflexes intact, pupils were equal and reactive to light bilaterally, conjunctiva were pink and sclera were white bilaterally
Nose, ears, and throat were normal.
Neck: no masses or lymphadenoapathy
Chest: clear to auscultation bilaterally, no wheezing/rhonchi
Abdomen: bowel sounds positive in all 4 quadrants, soft, no tenderness, no hepatosplenomegaly.
Neuro: face was symmetric. Strong sucking and rooting reflex. No muscle atrophy; he was able to move all extremities equally; normal tone; reflexes 2+ at patella, ankle, and biceps bilaterally; there was no head bobbing; tonic neck reflex was intact and symmetric.
Apart from the bilateral pendular nystagmus, Samuel’s physical examination was unremarkable. Nystagmus in an infant can represent both normal physiology and an alarming symptom for an underlying serious, but rare, disease. Though the majority of cases of nystagmus are considered congenital or infantile, 20% of nystagmus cases are acquired and require a full neurological workup.1 Infantile nystagmus occurs in the first 3 to 6 months of life, and acquired nystagmus develops after 6 months of life.2 Differentials for nystagmus in childhood vary from idiopathic, to ocular, and neurologic disorders (see Table 1).2 Therefore, primary care clinicians need to recognize and refer promptly if infantile nystagmus is observed, as it may be a symptom of a serious underlying disorder or a rare genetic disorder.
Table 1. Differentials for childhood nystagmus
|Infantile idiopathic nystagmus|
|Albinism associated: Achiasma|
|Retinal cone dystrophies: Achromatopsia; blue cone monochromatism; congenital stationary night blindness; Leber’s congenital amaurosis; Alstrom syndrome; Bardet-Biedl syndrome|
|Other ocular diseases: Retinopathy of prematurity; congenital cataracts; corneal opacities; optic nerve hypoplasia, atrophy, or coloboma; persistent hyperplastic primary vitreous; chorioretinal coloboma|
|Manifest latent nystagmus: Infantile squint syndrome|
|Neurologic diseases: Structural malformations; space-occupying lesions (glioma, craniopharyngioma); developmental diseases (Down syndrome, Noonan syndrome, Pelizaeus-Merzbacher disease, fetal alcohol syndrome, microcephaly); hydrocephalus; cerebral palsy; spinocerebellar ataxias; Chiari malformations; leukodystrophies; Joubert Syndrome|
Adapted from Papageorgiou, McLean, Gottlob.2
Evaluation and testing
Samuel was referred urgently to pediatric ophthalmology and pediatric neurology. Due to timing, he saw the ophthalmologist initially and was scheduled for an urgent MRI. His brain MRI was unremarkable and showed no evidence of cerebellar lesions. As a result, Samuel was diagnosed with congenital nystagmus and subsequently evaluated by a neurologist with recommendations to follow up in 1 month. At the 6-month well-child visit, the parents shared that they noticed that Samuel would always squint when exposed to any normal or bright light conditions. Samuel was reevaluated by the pediatric ophthalmologist, who discussed the possibility of a diagnosis of achromatopsia. Thus, Samuel was referred to a retina specialist for evaluation, diagnosis, and treatment recommendations.