Teaching Video NeuroImages: Cerebellar esotropia - A pitfall in ophthalmology and neurology¶

Summary¶

• 17yo F
• c/c
  • slowly progressive binocular horizontal diplopia
• PEx
  • distance esotropia
  • gaze-evoked nystagmus
  • broken smooth pursuit
  • reduced horizontal optokinetic nystagmus
  • impaired vestibulo-ocular reflex supression (VORS)
• Ex
  • MRI
    • type 1 Chiari malformation

Further¶

Terminology¶

• esotropia: 内斜視
• flocculus: 片葉
• paraflocculus: 傍片葉

Original¶

A 17-year-old girl presented with slowly progressive binocular horizontal diplopia, worse for distance viewing. She had distance esotropia (video), gaze-evoked nystagmus, broken smooth pursuit, reduced horizontal optokinetic nystagmus, and impaired vestibulo-ocular reflex suppression (VORS; video), in keeping with cerebellar dysfunction. The patient had full abduction during monocular viewing and head rotations, and normal saccadic velocities, excluding a bilateral sixth nerve palsy. An MRI scan confirmed a type 1 Chiari malformation (figure). A careful oculomotor assessment in patients with esotropia, including bedside VORS,¹ may identify cerebellar signs that would suggest the tropia is cerebellar in origin.² Cerebellar esotropia may arise from dorsal vermis impairment,² or possibly from floccular and parafloccular dysfunction, explaining the associated abnormalities in smooth pursuit, optokinetic nystagmus, and VORS that share common neural pathways.

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