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

Introduction 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. Case Presentation A 50 years 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 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 House-Brackmann grade of 5. MRI brain shows there is a small focal infarct at right pontine tegmentum, hypointensity in T1 sequence, hyperintensity in T2 sequence, and restricted in DWI sequence. He was treated as eight-and-a-half syndrome secondary to acute ischemic 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. Conclusion Recognition of eight-and-a-half syndrome allows precise anatomical localisation of this pontine lesion. Imaging is often used as a confirmatory tool. A wide range of differential diagnoses has to be considered.