A Rare Case of Eight-and-a-Half Syndrome Due to a Pontine Ischemic Stroke

Eight-and-a-half syndrome is an uncommon entity characterized by a combination of one-and-a-half syndrome and ipsilateral lower motor neuron facial palsy, typically resulting from a lesion in the dorsal pontine tegmentum. Although the clinical presentation may be striking, early diagnosis can be challenging due to subtle imaging findings in the hyperacute phase. We report the case of a 77-year-old man with no prior disability who presented to the emergency department (ED) with the sudden onset of headache, dizziness, vomiting, diplopia, dysarthria, and gait instability. Neurological examination revealed left lower motor neuron facial palsy, impaired ocular motility with limited adduction of the left eye, horizontal nystagmus, upbeat and downbeat nystagmus, and severe gait ataxia. The clinical constellation was consistent with eight-and-a-half syndrome. A non-contrast CT scan was unremarkable; however, given the acute presentation, intravenous thrombolysis was administered. An MRI performed later confirmed an ischemic lesion in the dorsal pons. The patient showed early neurological improvement and was discharged with a minimal increase in disability. At the three-month follow-up, he remained independent with partial resolution of cranial nerve deficits. We present this case to highlight the diagnostic value of detailed clinical examination in identifying uncommon brainstem syndromes, even when initial imaging is inconclusive. Recognition of eight-and-a-half syndrome at presentation can guide timely intervention and support clinical decision-making in the management of posterior circulation strokes. Documenting such cases enhances understanding of neuroanatomical correlations and reinforces the importance of clinical vigilance in acute stroke assessment.