Which form is associated with dorsal midbrain syndrome?

• A. Spasmus nutans
• B. Latent nystagmus
• C. Gaze-evoked nystagmus
• D. Convergence-retraction syndrome

Answer: (D)

Dorsal midbrain syndrome disrupts the vertical gaze pathways in the upper midbrain and affects the pretectal area, which also mediates the light–near reflex. A defining feature of this syndrome is convergence–retraction during attempts at upgaze: the eyes instead converge and retract into the orbits due to abnormal co-contraction of the horizontal and medial rectus muscles when the upward gaze system is stimulated. This convergence–retraction phenomenon, along with upgaze palsy and light–near dissociation, is a classic sign of dorsal midbrain (Parinaud) syndrome, often from a dorsal midbrain or pineal region lesion. The other forms listed have different origins and don’t specifically characterize dorsal midbrain syndrome (for example, spasmus nutans is infantile nystagmus with head bobbing; latent nystagmus arises with binocular disruption; gaze-evoked nystagmus reflects a gaze-holding disruption).