Gray matter overlying anterior basal temporal sulci as an intraoperative landmark for locating the temporal horn in amygdalohippocampectomies.

OBJECTIVE: Use of the gray matter overlying the anterior portions of the occipitotemporal and rhinal sulci as an intraoperative landmark for locating the temporal horn during amygdalohippocampectomies approached by the superior or lateral surface of the temporal lobe.
METHODS: The presence of occipitotemporal and rhinal sulci was analyzed in the magnetic resonance imaging scans of 165 patients who subsequently underwent mesial temporal resections, focusing on coronal slices up to 4 cm from the temporal pole. These sulci were used during surgery to locate the temporal horn in 150 surgeries. Five adult cadaveric heads whose vessels were perfused with colored silicone were used for photography.
RESULTS: These sulci are the principal sulci of the anterior basal temporal lobe. They were present in 154 out of 165 and 165 out of 165 patients, respectively. When approaching mesial temporal structures from the superior or lateral surface of the temporal lobe, dissection is initially performed through the white matter toward the floor of the middle fossa until the gray matter overlying an anterior basal sulcus is encountered. Dissection continues medially and superiorly from the top of the gray matter until the temporal horn is entered.
CONCLUSION: Gray matter overlying these sulci leads toward the anterior portion of the floor of the temporal horn and constitutes a landmark for locating the temporal horn. However, only the rhinal sulcus was always present. When both are present, the gray matter overlying the occipitotemporal sulcus is a reliable landmark. These landmarks are most suitable for mesial temporal resections without significant displacement of the temporal horn.