Optic pathways and brainstem involvement in posterior reversible encephalopathy syndrome

Posterior reversible encephalopathy syndrome (PRES) is a neurological syndrome manifesting with acute focal signs, and concomitant neuroimaging findings of vasogenic oedema. It affects the parieto-occipital regions in a vast majority of cases, although atypical variants have been described comprising the brainstem, basal ganglia or spinal cord. We report the case of a 41-year-old woman, admitted for persistent headache and inferior altitudinal field defect in the right eye. She presented with severe, non-medicated, hypertension. Brain MRI showed findings compatible with atypical PRES, involving the brainstem and optic pathways. With antihypertensive therapy the headache remitted, although visual field remained and was interpreted in the context of a vascular aetiology-non-arteritic anterior ischaemic optic neuropathy. MRI was repeated 3 weeks later and showed almost complete reversal of the previous changes.