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Background The intricate microanatomy of the human brainstem is clinically appreciable in a host of vascular syndromes which can be neuroradiologically correlated with known arterial territories. Isolated punctate infarcts of individual brainstem structures are much less common.Methods An 82-year-old ex-smoker developed acute vomiting and unsteadiness shortly after an elective coronary angiogram. There were no signs of lateral medullary ischaemia on examination, but right-sided internuclear-ophthalmoplegia (INO) with convergence insufficiency was present. The MRI brain revealed a 3mm infarct in the dorsal, paramedian region of the rostral pontine tegmentum. We reviewed the relevant neuroanatomy and associated literature to help correlate our findings.Results Lesions disrupting medial-longitudinal-fasciculus (MLF) interneurons connecting the abducens and contralateral oculomotor nuclei are well-known to cause INO. Concurrent convergence insufficiency denotes more rostral involvement. Dizziness and gait instability in these cases have been attributed to involvement of ascending MLF otolithic fibres that are involved in the vestibulo-ocular-reflex pathway.Isolated unilateral ischaemic INO has been considered a ‘unique clinical stroke syndrome’ (Kim, 2004) with variable pathogeneses. The risk of microemboli after coronary angiography, the end-artery properties of fine perforating vessels supplying the upper brainstem, and the susceptibility of heavily myelinated MLF nerve fibres to damage from any cause may all contribute to this unique stroke syndrome.Conclusion The clinical assessment of posterior-fossa vascular syndromes requires careful neuroanatomical correlation. Small strategic infarcts of isolated structures present unique opportunities to clinically demonstrate the physiological significance of individual tracts. As Charles Miller-Fisher (1913–2012) would fondly say: ‘we learn neurology stroke by stroke.’