Gaurav Jindal, MD | Yale–New Haven Hospital, New Haven, Connecticut Aubrey Gilbert, MD, PhD | Massachusetts Eye and Ear Infirmary, Boston, Massachusetts Rafeeque Bhadelia, MD | Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts Nurhan Torun, MD | Division of Ophthalmology, Department of Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts
A provisional clinical diagnosis was made of right trochlear nerve palsy and left abducens nerve palsy, with the assumption that one was chronic and the other new, because simultaneous onset seemed unlikely. Axial T1 postcontrast magnetic resonance imaging (MRI) revealed an enhancing lesion in the right ambient cistern along the course of the trochlear nerve, consistent with right trochlear nerve schwannoma (Figure 1) and thin section axial FIESTA images revealed left abducens nerve compression by an anterior inferior cerebellar artery (AICA) aneurysm (Figure 2).
Axial T1 postcontrast image revealing an enhancing lesion in the right ambient cistern along the course of the right trochlear nerve (white arrow) consistent with right fourth nerve schwannoma.
Thin-section axial FIESTA image revealing left sixth nerve compression by an anterior inferior cerebellar artery aneurysm (black arrowhead). The cisternal segment of the normal sixth nerve is seen on the right (black arrow).