A Rare Pontine Neuro-ophthalmic Syndrome: Eight-and-a-Half Syndrome

One-and-a half syndrome is seen in paramedian pontine lesions, and may also co-exist with cranial nerve paralysis. This clinical situation is called eight-and-a-half syndrome when facial nerve paralysis also accompanies this manifestation. A man aged 38 years was admitted with symptoms of sudden-onset binocular diplopia and dizziness. The patient had no known co-morbidities. Cranial magnetic resonance imaging showed a small-sized infarct in the left paramedian pontine tegmentum posterior area. In his neuro-ophthalmologic examination, total paresis of left eye horizontal movements, mild lateral deviation, and monocular nystagmus during abduction of the right eye were observed. The patient also had peripheral facial paralysis on the left side; therefore, no signs of motor deficit of his extremities were examined. Eight-and-a-half syndrome is a rare disorder that is seen in localized-small pons lesions, mostly accompanied by infarcts. This clinical manifestation is called eight-and-a-half syndrome and arises within lesions in both the parapontine reticular formation and the medial longitudinal fasciculus in the inferior pons tegmentum where horizontal eye movements are controlled, and facial axons adjacent to the nucleus of the sixth nerve. We wanted to present this case to emphasize this rare situation.