# Eight-and-a-Half Syndrome Secondary to Acute Brainstem Infarction

## TL;DR

This paper reports a rare case of eight-and-a-half syndrome caused by a brainstem stroke and highlights the potential for recovery with timely treatment.

## Contribution

The paper presents a novel clinical case of eight-and-a-half syndrome due to acute brainstem infarction and emphasizes recovery outcomes.

## Key findings

- Eight-and-a-half syndrome was diagnosed via MRI showing infarction in the left thalamus and brainstem.
- The patient showed complete resolution of ophthalmoplegia after three months of treatment.
- Minimal residual facial nerve weakness was observed despite significant recovery.

## Abstract

Eight-and-a-half syndrome is a rare neuro-ophthalmologic condition, which is characterized by ipsilateral horizontal gaze palsy, internuclear ophthalmoplegia (INO), and ipsilateral lower motor neuron facial palsy. We report a case of eight-and-a-half syndrome secondary to acute brainstem infarction.

A 55-year-old gentleman with underlying diabetes mellitus and hypertension presented with a sudden onset of double vision in the right lateral gaze for one day. On examination, there was a limitation in the left eye horizontal eye movement with limited right eye adduction. Further neurological examination revealed left lower motor neuron facial nerve palsy. Magnetic resonance imaging (MRI) of the brain showed an acute infarct involving the left side of the thalamus extending to the left side of the midbrain, pons, and medulla. He was diagnosed with eight-and-a-half syndrome secondary to acute brainstem infarction. The patient was referred to the neuromedical team, where he was treated with anti-platelet medications. He showed gradual improvement on follow-up and had complete resolution of ophthalmoplegia after three months. There was only minimal residual facial nerve weakness.

Eight-and-a-half syndrome has a localizing value to the dorsal tegmentum of the pons. It requires thorough neurological examination and imaging studies for accurate diagnosis and management. This case highlights the potential for a significant recovery in patients with eight-and-a-half syndrome when timely and appropriate treatment is administered.