Abstracts

Rationale:
MRI-guided laser ablation therapy is a very target specific relatively new surgical technique that offers a minimally-invasive option for treatment of drug resistant temporal lobe epilepsy.  Because it is more targeted than temporal lobectomy, more specific patient factors that may influence surgical outcomes with this technique need to be identified. We explored factors that yield the best surgical outcomes.
Method:
We prospectively tracked and retrospectively reviewed consecutive laser ablation surgeries for mesial temporal epilepsy (including but not limited to hippocampal sclerosis) from January 2013 to November 2018 at Harborview Regional Epilepsy Center of University of Washington.  A total of 107 laser ablations were performed on patients ages 17-80 years for medically refractory temporal lobe epilepsy We collected Engel outcome (both at 1-year and last follow-up), pre-operative seizure frequency, seizure semiology, EEG findings, MRI, other imaging (when available), and neuropsychology results. Furthermore, we retrospectively did a blinded review of pre-operative MRI images, and categorized preoperative findings such as seizure semiology.
Results:
Of the 107 cases, 3 underwent a second ablation of the same region.  This results in 104 individual patients. The outcomes for these 3 cases are reported here after the second ablation (based on review of MRI data from the first ablation).  One other patient was excluded from the analysis since she had bitemporal epilepsy and the ablation was done for palliative purposes (after failed responsive neuro-stimulation).  Outcome data was obtained for these 103 patients.  One year Engel outcome data was available for 93 patients. A total of 41 out of 93 (44%) patients achieved an Engel Class I outcome at 1-year follow up.  A majority (65 of the 93 cases) were performed on the left, presumably because of patient and provider preferences for a limited tissue removal for dominant hemisphere epilepsy. Presence of clear ipsilateral MTS was associated with a better outcome.  Lack of interictal epileptiform abnormalities was associated with worse outcome.  There was a trend towards frequent GTC seizures being associated with worse outcomes but was not statistically significant at p 0.05.  There were other small differences though these were not near statistical significance.
Conclusion:
The findings of this study suggest that hippocampus laser ablation is a great option for patients with clear ipsilateral MTS on MRI as well as interictal evidence of temporal lobe epilepsy.  Other patients with temporal lobe epilepsy seem to benefit though seizure freedom rates may be lower.  Additional selection criteria need to be verified with larger dataset. 
Funding:
:None