“Sixteen syndrome”—a new pontine ophthalmo-neurological syndrome within the one-and-a-half syndrome spectrum of disorders: case report and literature review

The one-and-a-half syndrome is a term originally proposed by Fisher to describe a syndrome with ocular dyskinesia, exhibiting ipsilateral conjugate gaze palsy and ipsilateral internuclear ophthalmoplegia (INO) (1). The underlying pathological lesion is frequently at the level of the unilateral tegmentum, affecting the paramedian pontine reticular formation (PPRF), abducens nucleus, and medial longitudinal fasciculus (MLF). The lesion is mainly caused by cerebrovascular disease leading to pontocerebral infarction. After the first report of the one-anda-half syndrome, several numbered ophthalmo-pontine neurological syndromes have been reported with the clinical features of the one-and-a-half syndrome appearing in all subsequent reports. Accordingly, the clinical features of the numbered ophthalmo-pontine syndromes are indicative of the precise locus of the lesion, highlighting the clinical significance. We here report a case of “sixteen syndromes”, which we believe to be the first case of its kind to be reported in the literature.