Eight-and-a-Half Syndrome: An Uncommon but Potentially Life-Threatening Disease Secondary to Acute Brainstem Infarction

A localized pontine lesion affecting the abducens nucleus or paramedian pontine reticular formation (PPRF), the medial longitudinal fasciculus (MLF), and the facial nerve fascicle results in eight-and-a-half syndrome, a rare neurological condition. It manifests as ipsilateral peripheral facial nerve palsy, internuclear ophthalmoplegia (INO), and horizontal gaze palsy. This condition typically indicates a minor but well-placed infarct in the dorsal pons. We diagnosed eight-and-a-half syndrome in a patient who presented with dizziness and double vision, with a background history of hypertension and type 2 diabetes mellitus. A neurological examination showed right-sided lower motor neuron face paralysis, INO in the contralateral eye, and horizontal gaze palsy to the right, all of which are indicative of eight-and-a-half syndrome. An acute ischemic infarct was seen on magnetic resonance imaging (MRI) in the right posterior pons, which is next to the fourth ventricle. The patient started on a high-dose statin, dual antiplatelet therapy, and supportive care. His symptoms gradually improved over the next few weeks. The clinical significance of eight-and-a-half syndrome as a sign of localized pontine infarction is demonstrated by this instance. Neuroimaging and early detection are crucial for diagnosis and prompt stroke treatment.