A rare neuro-ophthalmological presentation of Nine syndrome: clinical radiological-anatomical correlation

Abstract

Nine syndrome is a very rare neuro-ophthalmological entity resulting from combined involvement of the abducens nucleus or paramedian pontine reticular formation (PPRF), the medial longitudinal fasciculus (MLF), the facial colliculus, and the corticospinal tract. This constellation produces the combination of horizontal gaze palsy, internuclear ophthalmoplegia, ipsilateral facial palsy, and contralateral hemiparesis/ hemianesthesia/ hemiataxia together constitute Nine syndrome (7^th nerve+1 and 1/2 syndrome+1/2 hemiparesis/ hemianesthesia/ hemiataxia). Our objective was to present a case of nine syndrome providing a comprehensive clinical examination, detailed radiological evaluation and anatomical correlation to explain the neurological findings. This case highlights the importance of recognizing characteristic neuro-anatomical correlations in pontine stroke syndromes. We report a case of a 57-year-old male who presented with sudden-onset left hemiplegia, dysarthria, and binocular diplopia. Neurological examination revealed right horizontal conjugate gaze palsy, right internuclear ophthalmoplegia, right lower motor neuron facial palsy, and left hemiplegia-clinically consistent with nine syndrome. MRI brain revealed an acute right paramedian pontine infarct with basilar artery aneurysm. The patient was managed with antiplatelet therapy, high-intensity statin, glycemic control, and supportive care. Clinical improvement was noted over the following days. This case highlights the importance of recognizing combined cranial nerve and long-tract signs in localizing pontine lesions. Nine syndrome, though rare, should be considered in patients presenting with horizontal gaze palsies and contralateral hemiparesis and aggressive vascular risk-factor management is critical for preventing recurrence.