Atypical "nine" syndrome in bilateral pontine infarction: A case report

"Nine" syndrome, that is "eight-and-a-half" syndrome associated with hemiplegia and hemidysesthesia, is a rare disorder. This study aimed to report a Chinese patient with acute bilateral pontine infarction manifesting as eight-and-a-half syndrome plus hemiplegia (atypical nine syndrome), and also the clinical and neuroimaging findings were explained and discussed with review of the literature.

A 79-year-old woman experienced sudden vertigo, nausea, vomiting, and weakness at her left arm and leg. The neurological examination disclosed her right horizontal gaze palsy, internuclear ophtalmoplegia (INO), and right-sided peripheral facial paralysis combined with slight left-sided hemiplegia, which were consistent with atypical nine syndrome.

Cranial magnetic resonance imaging (MRI) displayed acute multiple ischemic infarction, involving bilateral pontine tegmentum, basilar part of right paramedian pontine, and left cerebellar hemisphere. Intracranial MR angiography (MRA) revealed right middle cerebral artery occlusion, no clear visualization of bilateral vertebral arteries, and basilar artery hypoplasia with stenotic segments.

Thrombolysis could not be performed due to the time window. The patient was given low molecular weight heparin for anticoagulation because of posterior circulation and progressive stroke.

The vertigo disappeared, and a notable improvement with minimal restriction in the right horizontal gaze and partial relief of her facial paralysis were found at discharge, while her left hemiparesis was fully resolved. No recurrence of cerebral infarction was observed during follow-up as well.

This case report with atypical nine syndrome is fairly rare. Nine syndrome may refer to the lesion located in unilateral tegmentum of the caudal pontine plus paramedian pontine, with an important localization value.