Painful isolated Horner's syndrome caused by pontine ischaemia

Purpose. To alert ophthalmologists to the possibility of brainstem ischaemia in patients with isolated Horner's syndrome. Design. Observational case report. Methods. Neuro-ophthalmological and neuroimaging assessment of a 59-year-old woman presenting with an isolated Horner's syndrome after an episode of headache. Results. Horner's syndrome was pharmacologically localised to a first- or second-order sympathetic neuron on the right. Magnetic resonance imaging (MRI) showed a small ischaemic lesion at the transition between pons and midbrain, lateral to the anterolateral system involving the sympathetic tract on the right side. Conclusion. An isolated Horner's syndrome may be the presenting sign of a brainstem infarction. This case report stresses the importance of a rational approach to Horner's syndrome and the need to order accurate MRI.