Clinicoradiologic Correlation in Bilateral Internuclear Ophthalmoplegia Revealing a Ruptured Pontine Abscess.

Internuclear ophthalmoplegia (INO) is an uncommon but well-recognized clinical sign, most frequently associated with demyelinating disorders or brainstem infarction. Its occurrence in the context of an infectious process, particularly a brainstem abscess, is exceptional. We report the case of a previously healthy 37-year-old man who presented with acute meningeal signs and binocular horizontal diplopia. Magnetic resonance imaging (MRI) revealed a ring-enhancing pontine lesion with diffusion restriction and posterior interruption of enhancement at the interface with the fourth ventricle, consistent with a ruptured brainstem abscess. The patient responded favorably to empirical intravenous antibiotic therapy and achieved complete clinical recovery. This case is noteworthy because of the unusual anatomical location of the abscess and its distinctive clinical presentation, underscoring the crucial role of imaging in early diagnosis. It further emphasizes that infectious etiologies should be considered in patients presenting with INO and shows how specific MRI features can help in distinguishing infectious from non-infectious pontine lesions.