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

Abstract

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 < .05). Two-laser trajectories achieved full ablation of MTL cortical structures at physiologically realistic burn radii, whereas one-laser trajectories could not. Five patients with at least 1 year of follow-up (mean = 21.8 months) experienced Engel class I outcomes; 6 patients with less than 1 year of follow-up (mean = 6.6 months) are on track for Engel class I outcomes.

Seizure onset patterns predict outcome after stereotactic electroencephalography-guided laser amygdalohippocampotomy

“…40 Another analysis of 28 patients found that patients with Engel I outcomes had a higher percentage of PHG ablated, 41 and a recent study of 11 patients undergoing a two-trajectory approach to target the piriform and entorhinal cortex suggested improved outcomes. 42 Conversely, other studies have found no correlation with ablation of these regions and outcome. 43,44 Some centers now use two fibers including an oblique lateral entry point to cover the amygdala and entorhinal cortex.…”

Temporal lobe epilepsy surgery: Piriform cortex resection impacts seizure control in the long‐term

“…In the recently published study, Liu et al. showed that additional trajectory to achieve more extensive ablation of hippocampus, amygdala, and PiC in LITT procedures is more likely associated with seizure freedom 20 . Despite the progress in the field of minimally invasive surgical techniques, the selective epilepsy surgery procedures including tsSAHE remain effective and safe treatment options in mTLE.…”

Quelling the Area Tempesta: Removal of the Piriform Cortex Improves the Outcomes of Surgery for Temporal Lobe Epilepsy

“…Liu et al showed how a two-trajectory laser amygdalohippocampotomy including hippocampus, amygdala, and piriform/entorhinal/perirhinal cortex was superior in full ablation and seizure outcomes. 12 This more extensive ablation including the PC was correlated with the outcome of seizure freedom. Hwang et al performed preablation and postablation volumetric analyses of hippocampus, amygdala, PC, and ablation volumes in 39 patients with mTLE who underwent LITT and found that with multivariable logistic regression only percent PC ablation was a significant predictor of seizure freedom at 6 months (Odds Ratio (OR) 1.085, 95% Confidence Interval (CI) [1.012-1.193], P = .019) and at 1 year (OR 1.074, 95% CI [1.003-1.178], P = .041).…”