Laser thermal ablation for mesiotemporal epilepsy: Analysis of ablation volumes and trajectories

Abstract

Objective To identify features of ablations and trajectories that correlate with optimal seizure control and minimize the risk of neurocognitive deficits in patients undergoing laser interstitial thermal therapy (LiTT) for mesiotemporal epilepsy (mTLE). Methods Clinical and radiographic data were reviewed from a prospectively maintained database of all patients undergoing LiTT for the treatment of mTLE at the University of Miami Hospital. Standard pre- and post-operative evaluations, including contrast-enhanced MRI and neuropsychological testing, were performed in all patients. Laser trajectory and ablation volumes were computed both by manual tracing of mesiotemporal structures and by non-rigid registration of ablation cavities to a common reference system based on 7T MRI data. Results Among 23 patients with at least one-year follow-up, 15 (65%) were free of disabling seizures since the time of their surgery. Sparing of mesial hippocampal head was significantly correlated with persistent disabling seizures (p = 0.01). A lateral trajectory through the hippocampus showed a trend for poor seizure outcome (p = 0.08). Comparison of baseline and postoperative neurocognitive testing revealed areas of both improvement and worsening, which were not associated with ablation volume or trajectory. Significance At one-year follow-up, LiTT appears to be a safe and effective tool for the treatment of mTLE, though a longer follow-up period is necessary to confirm these observations. Better understanding of the impact of ablation volume and location could potentially fine-tune this technique to improve seizure freedom rates and associated neurological and cognitive changes.

Stereotactic EEG-guided laser interstitial thermal therapy for mesial temporal lobe epilepsy

“…In the most recently published study which was not included in the mini-review, class I outcome was achieved in 11 (73%) of 15 patients with MTS and in 5 (62%) of 8 patients without MTS. There was no statistical difference of class I outcome in patients with MTS and without MTS 25. When combining all the published cases including those in the current study, class I seizure outcome was achieved in 36 (67%) of 54 patients with MTS and 9 (38%) of 24 patients without MTS.…”

Laser ablation is effective for temporal lobe epilepsy with and without mesial temporal sclerosis if hippocampal seizure onsets are localized by stereoelectroencephalography

“…The largest and most favorable experience is reported in Jermakowicz et al 6 In their series of 23 SLAH patients, 5 of 8 (63%) without MTS were seizurefree with a minimum 1-year follow-up. Use of intracranial depth electrodes to confirm seizure onset in this population is variable.…”

“…Patients unwilling to consider open surgery may be more amenable to a minimally invasive approach. Oneyear seizure freedom rates have been reported in fewer than 50 patients, [2][3][4][5][6]13 and it will be several years before the results of the Stereotactic Laser Ablation for Temporal Lobe Epilepsy (SLATE) trial-an ongoing, large prospective cohort study-are available. 3,5 Some have suggested that SLAH may be the preferable first-line surgical option for MTLE, with open surgery reserved for those with persistent seizures after one or more failed ablations.…”

Curative and palliative MRI-guided laser ablation for drug-resistant epilepsy

“…LITT typically includes ablation of tissue anterior to the hippocampus, while the posterior margin is limited to avoid damaging optic radiations that might lead to visual field deficits. A recent report indicated that sparing of the medial parts of the hippocampal head significantly decreased the likelihood for good seizure outcome17; however, future research is needed to confirm this. Likewise, the ideal trajectories for mesial temporal ablation are unclear.…”

“…Further analysis of ablations within this area in 23 patients found that the sparing of the medial hippocampal head was associated with significantly worse seizure outcome 17. This raises the question of whether, when a single trajectory approach is used, it should always be angled in such a way that ablation of the medial hippocampal head is accomplished.…”