Superior oblique paresis with contralateral relative afferent pupillary defect.

Background: The purpose of this study is to report a case of superior oblique paresis and contralateral relative afferent pupillary defect (RAPD) with normal vision in a patient with brainstem astrocytoma.
Methods: We correlated the patient's clinical findings with anatomical substrates on magnetic resonance imaging (MRI) findings.
Results: The patient had right-sided superior oblique paresis. There was a left-sided RAPD, although visual acuities and visual fields were normal in both eyes. T1-weighted, gadolinium-enhanced MRI demonstrated a hyperintense area in the right dorsal midbrain.
Conclusion: It is suggested that the lesion damaged both the pretectal afferent pupillary pathway and fascicles of the trochlear nerve, causing a unique combination of neuro-ophthalmologic findings.