An 18-month-old boy develops fine, rapid, small-amplitude nystagmus that appears asymmetric in the two eyes, together with head nodding and an abnormal head posture. Neuroimaging is normal and the nystagmus resolves spontaneously by age 4 years. Which condition does this describe?
- A Congenital (infantile) motor nystagmus
- B Spasmus nutans ✓
- C Latent nystagmus associated with infantile esotropia
- D See-saw nystagmus of parasellar origin
Correct answer: B. Spasmus nutans
Explanation
Spasmus nutans is the classic triad of fine, fast, dissociated (asymmetric) nystagmus, head nodding, and torticollis, appearing between about 6 months and 3 years and resolving spontaneously by school age with normal development and imaging. Infantile motor nystagmus begins earlier, is conjugate rather than dissociated, persists lifelong, and often has a null point. Latent nystagmus appears only when one eye is occluded and accompanies early-onset strabismus, so its conjugate, persistent nature kills that distractor.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.