Nine Syndrome: Case Report and Review of Clinical Signs in Internuclear Ophthalmoplegia

The pathologic involvement of brainstem and midbrain nuclei and white matter tracts in various combinations may result in a spectrum of arithmetically derived syndromes. They include ‘one and a half syndrome’, ‘eight and a half syndrome’ and ‘fifteen and a half syndrome’. We report a case of ‘nine syndrome’, which has been reported more recently, caused by caused by acute pontine infarcts and characterised clinically by a combination of internuclear ophthalmolplegia, ipsilateral horizontal gaze palsy, lower motor neuron type of facial palsy, contralateral hemiparesis and hemianesthesia. We highlight the genesis of this combination of clinical signs, revisit the different variants of INO and review the literature on ‘Nine syndrome’.