Two‐trajectory laser amygdalohippocampotomy: Anatomic modeling and initial seizure outcomes

Objective Laser interstitial thermal therapy (LITT) for mesial temporal lobe epilepsy (mTLE) is typically performed with one trajectory to target the medial temporal lobe (MTL). MTL structures such as piriform and entorhinal cortex are epileptogenic, but due to their relative geometry, they are difficult to target with one trajectory while simultaneously maintaining adequate ablation of the amygdala and hippocampus. We hypothesized that a two‐trajectory approach could improve ablation of all relevant MTL structures. First, we created large‐scale computer simulations to compare idealized one‐ vs two‐trajectory approaches. A two‐trajectory approach was then validated in an initial cohort of patients. Methods We used magnetic resonance imaging (MRI) from the Human Connectome Project (HCP) to create subject‐specific target structures consisting of hippocampus, amygdala, and piriform/entorhinal/perirhinal cortex. An algorithm searched for safe potential trajectories along the hippocampal axis (catheter one) and along the amygdala‐piriform axis (catheter two) and compared this to a single trajectory optimized over all structures. The proportion of each structure ablated at various burn radii was evaluated. A cohort of 11 consecutive patients with mTLE received two‐trajectory LITT; demographic, operative, and outcome data were collected. Results The two‐trajectory approach was superior to the one‐trajectory approach at nearly all burn radii for all hippocampal subfields and amygdala nuclei (p