Eight-and-a-Half Syndrome as Presentation of Pontine Infarct—A Case Report

Eight-and-a-half syndrome is a rare neuro-ophthalmologic syndrome in which the lesion is at the dorsal tegmentum of caudal pons. The syndrome comprises conjugate horizontal gaze palsy and ipsilateral internuclear ophthalmoplegia (one-and-a-half syndrome), coupled with ipsilateral facial nerve palsy. A 50-year-old male teacher with underlying uncontrolled diabetes mellitus and hypertension presented with abrupt onset of diplopia and right facial asymmetry. Clinically, he was alert and conscious. Examination revealed left eye exotropia, bilateral eye conjugate right gaze palsy, impaired adduction of the right eye, and left eye developed jerk nystagmus to the right upon abduction. There was binocular horizontal diplopia in all directions of gaze. Vestibulo-ocular reflex was absent in both eyes. Besides, he had right hemifacial palsy with a House-Brackmann grade of 5. MRI brain shows there is a small focal infarct at the right pontine tegmentum, hypointensity in the T1 sequence, hyperintensity in the T2 sequence, and restricted in the DWI sequence. He was treated for eight-and-a-half syndrome secondary to acute ischaemic stroke with the involvement of vertebrobasilar artery territory, causing lacunar infarct in the right pontine tegmentum. The risk factors were uncontrolled diabetes mellitus and hypertension. After 6 weeks of medical treatment, his facial weakness had improved significantly. The left eye extotropia and right eye adduction have completely resolved. Nonetheless, there is residual right gaze palsy. Recognition of eight-and-a-half syndrome allows precise anatomical localization of this pontine lesion. Imaging is often used as a confirmatory tool. A wide range of differential diagnoses has to be considered.