Hemiparkinsonism due to a pontomesencephalic cavernoma: improvement after resection. Case report.

Cavernous angiomas of the upper brainstem causing hemiparkinsonism are very rare. Due to their difficult-to-reach localization, brainstem cavernomas, in particular those in anterior locations, continue to present a therapeutic challenge. The authors report on a 16-year-old boy with a pontomesencephalic cavernoma who developed hemiparkinsonism and hemiparesis after hemorrhage. After complete surgical removal of the pontomesencephalic cavernoma via a pterional transsylvian approach, his symptoms resolved. Although pontomesencephalic cavernomas occupying the ventral portion of the brainstem are regarded as problematic for resection, the pterional transsylvian approach provides an excellent route for removal of cavernomas that are in contact with the ventral surface of the midbrain in the interpeduncular cistern. Surgical removal of this type of lesion is recommended because resolution of clinical symptoms, including hemiparkinsonism, can be achieved.