Lateral transsulcal approach to asymptomatic trigonal meningiomas with correlative microsurgical anatomy: technical case report.

OBJECTIVE: We introduce the lateral transsulcal approach to asymptomatic trigonal meningiomas.
METHODS: The approach was studied in two cadaver brains and three asymptomatic patients with trigonal meningiomas. The posterior part of the sylvian fissure, or superior temporal sulcus, is opened to the bottom. Through a small horizontal cortical incision, the trigone of the lateral ventricle is exposed in the shortest distance. The trigonal meningiomas are detached from the choroid plexus and removed.
RESULTS: In patients with meningiomas on the nondominant side, the transsylvian approach was adopted. In patients with meningiomas on the dominant side, the transsylvian approach was adopted for patients with a wide sylvian cistern, and the approach through the superior temporal sulcus was adopted for patients with a narrow sylvian cistern. The transverse gyrus of Heschl was a good anatomic landmark in the operative field of the transsylvian approach. Patients with meningiomas on the dominant side exhibited transient amnestic aphasia and dyscalculia, but the symptoms disappeared in a few days or weeks. These patients were discharged without any neurological deficits. Although there are potential risks of damaging association fibers, optic radiation, the transverse gyrus of Heschl, and the parietal lobe, a thorough understanding of the topographical anatomy and careful dissection techniques can avoid morbidity. Wide opening of the sylvian fissure and debulking of the tumor are other important factors to reduce the retraction of the parietal and temporal lobes.
CONCLUSION: The lateral transsulcal approach is applicable for small asymptomatic trigonal meningiomas with an acceptable risk of morbidity, even in the dominant hemisphere.