A 50-year-old man presents with inability to look to the right with either eye, plus failure of adduction of the right eye on attempted left gaze. The only remaining horizontal eye movement is abduction of the left eye with nystagmus. This is called:

• A Bilateral internuclear ophthalmoplegia
• B Millard-Gubler syndrome
• C Parinaud dorsal midbrain syndrome
• D One-and-a-half syndrome ✓

Explanation

One-and-a-half syndrome consists of a horizontal gaze palsy in one direction (the 'one') plus an internuclear ophthalmoplegia in the other direction (the 'half'). It results from a single pontine lesion affecting both the abducens nucleus (or PPRF) and the ipsilateral MLF. Millard-Gubler involves CN VI and VII palsy with contralateral hemiparesis. Parinaud syndrome affects vertical gaze.

Reference: Clinical Neuroanatomy, 28th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.