The daily educational pearl – One-and-a-half syndrome

One-and-a-half syndrome

= caused by lesions of the dorsal pons


– ipsilateral conjugate horizontal gaze palsy

– internuclear ophthalmoplegia on contralateral gaze

– exotropia of the eye opposite to the side of the lesion


– any lesions causing compression of the dorsal pons – trauma, neoplasms, hydrocephalus

– pontine haemorrhage

– ischaemia – thromboembolic / vasculitis

– multiple sclerosis