[Paramedian dorsal syndrome of mesencephalic tegmentum]

Two cases of brainstem infarction involving a unilateral side of the midbrain tegmentum showed a peculiar ocular symptom complex. The ocular syndrome consisted of (1) oculomotor palsy ipsilateral to the lesion, (2) monocular eyelid retraction and upward gaze palsy contralateral to the lesion, and (3) conjugate downward gaze and convergence palsy. By computed tomography and cerebral angiography, the lesion shared by the two cases was identified in the territory of median mesencephalic rami originating from the posterior cerebral artery. The lesion involved oculomotor nucleus on a side. Contralateral monocular symptoms and conjugate palsies could be attributed to a damage in their supranuclear tracts. Considering with two similar cases in the literature, it is strongly suggested that a unilateral ischemic lesion of the paramedian dorsal part of the midbrain tegmentum is responsible for this syndrome. Bilateral or unilateral eyelid retraction (Collier's sign) was considered to locate a lesion in the posterior commisure by Collier himself. The posterior commisure is, however, not involved in our two cases, and a paramedian lesion of the midbrain tegmentum deviated to a side may cause contralateral eyelid retraction. A combination of ophthalmoplegia ipsilateral to the lesion, upward or lateral (in the opposite direction to the lesion) gaze palsy, and hemiataxia on the contralateral side resembling our second case is sometimes erroneously called Nothnagel's syndrome. Nothnagel mentioned symptomatology of the quadrigeminal bodies for local diagnosis in his text in which he did not describe this combination of signs.