Introduction: Surgical resection of the mesial temporal lobe is the standard of care for medically intractable epilepsy arising from mesial temporal sclerosis. Despite its highly favorable risk-benefit ratio, temporal craniotomy carries certain risks, including retraction injury, stroke, and cognitive dysfunction from white matter tract disruption. Many of these complications are related to exposure of the lateral temporal lobe. In cadaveric specimens, we investigated transorbital endoscopic amygdalo-hippocampectomy (TEA) as an alternative to open craniotomy. This approach provides a direct route to the temporal pole and mesial temporal structures via the lateral orbital wall.
Methods: Dissections were performed in two cadaveric heads (four hemispheres) that were fixed with alcohol and injected with latex for blood vessel visualization. Standard neuroendoscopes provided visualization of the intracranial space. Pre- and post-dissection computed tomography (CT) and magnetic resonance (MR) images were obtained for the purposes of neuro-navigation and recording the extent of resection. Quantitative predictions of the limits of exposure based on pre-dissection imaging were compared to intra-dissection measurements and validated with images from 10 epilepsy patients undergoing surgical evaluation.
Results: The transorbital approach permitted up to 97% of the hippocampal formation to be resected with no brain retraction and minimal globe retraction (6.0 ± 1.4 mm). Temporal lobe white tracts were preserved. A wide range of intracranial structures could be accessed with TEA methods. No significant differences were found between MRI-based predictions of angles of exposures and intra-dissection measurements.
Conclusions: TEA is a feasible alternative to standard craniotomy for near-total amygdalo-hippocampectomy. The transorbital approach could result in better patient outcomes because it spares the lateral temporal lobe and white matter pathways and removes the need for brain retraction. These results support further investigation of this novel surgical approach.
Patient Care: Our proposed surgical alternative to conventional open craniotomy for mesial temporal lobe surgical has the potential to improve patient outcomes by (1) avoiding the complications associated with open temporal lobe exposure and (2) reducing cognitive deficits by preserving temporal white matter tracts.
Learning Objectives: By the conclusion of this session, participants should be able to: (1) Describe the complications associated with open craniotomy for temporal lobe access, (2) understand the technique of transorbital endoscopic amygdalo-hippocampectomy (TEA), and (3) define the benefits and potential risks of the TEA approach.