In this patient, a left paramedian midbrain infarction, as shown by the restricted diffusion and T2 hyperintensity on MRI, resulted in an ipsilateral (left) oculomotor palsy and contralateral (right) trochlear palsy. The presence of right hypertropia and worse diplopia on left lateral gaze and on tilting the head to the right is consistent with right superior oblique weakness due to right trochlear palsy. The Hess chart, performed 2 weeks after presentation, demonstrates under action of the right superior oblique, and the similarity in right and left eye ‘‘box size” suggests a degree of compensation. The mild ipsilateral ataxia may have been due to involvement of fibres of the superior cerebellar peduncule, caudal to their decussation. Although midbrain infarction can lead to vertical ocular misalignment or skew deviation, this would be expected to result in contralateral eye hypodeviation – in this patient a right eye hypodeviation, rather than the observed right hypertropia. Furthermore, the head tilt test is usually negative in skew deviation, unless there is a spread of comitance. Intorsion of the uppermost and extorsion of the lowermost eye is expected, whereas in trochlear palsy, the uppermost eye is typically extorted. In the presence of an oculomotor palsy, a concomitant ipsilateral trochlear lesion can be identified if intorsion is impaired or absent; however, a concomitant contralateral trochlear lesion is difficult to discern as both lesions result in vertical misalignment, with the ipsilateral eye showing hypodeviation and the contralateral eye, hyperdeviation. The combination of left oculomotor and right trochlear palsies is puzzling until midbrain anatomy is recalled. Oculomotor fibres project ipsilaterally, but trochlear fibres decussate within the medullary vellum to innervate the contralateral superior oblique (Fig. 1). Similar presentations have been reported after dorsal paramedian infarction including ipsilateral internuclear ophthalmoplegia with contralateral trochlear palsy, ipsilateral Horner’s