One-and-a-half syndrome

= caused by lesions of the dorsal pons

Signs:

– ipsilateral conjugate horizontal gaze palsy

– internuclear ophthalmoplegia on contralateral gaze

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

Causes:

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

– pontine haemorrhage

– ischaemia – thromboembolic / vasculitis

– multiple sclerosis