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Neurology Today Conference Reporter: AES Annual Meeting

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Tuesday, December 4, 2018

New Data on Long-Term Outcomes for Laser Ablation for Mesial Temporal Lobe Epilepsy

BY THOMAS R. COLLINS

NEW ORLEANS—Laser interstitial thermal therapy, a less invasive treatment for patients with mesial temporal lobe epilepsy, is associated with neurocognitive deficits and visual field loss, according to a study of long-term outcomes presented here at the American Epilepsy Society annual meeting.

Researchers also found that patients with etiologies other than mesial temporal sclerosis are less likely to have freedom from seizures, said Akta Patel, DO, a clinical neurophysiology fellow at Mayo Clinic in Scottsdale, AZ.

These are the latest findings to shed light on the challenges that patients face after the surgery, and they could help prepare them as they consider their treatment options, Dr. Patel said.

"Based on our results, patients with mesial temporal lobe sclerosis have the best outcomes," she said. "This is also generally true for patients who undergo anterior temporal lobectomy according to the literature. Additionally, laser ablation, on average, has shorter hospital stays and lower perioperative side effects. It will be helpful to have more information for our patients when having discussions about which procedure is best for them."

Researchers reviewed charts for 25 patients who underwent magnetic resonance-guided laser interstitial thermal therapy, with an average follow-up ranging from eight days to about four years. On average, they had follow-up data for about 1.5 years after surgery.

MRI scans showed that 12 patients had findings of medial temporal sclerosis, and eight of those patients showed freedom from disabling seizures, while none of the other 13 patients with either normal or other magnetic resonance imaging findings were seizure-free.

The researchers also found that eight of the 10 patients for whom they had pre- and post-surgery assessments showed declines on neuropsychometric testing. And five out of 11 patients who had formal visual field testing had post-operative deficits.

Because of ongoing seizures, researchers found, one patient returned for further anterior temporal lobe ablation (ATL), two for anterior temporal lobectomy, and one patient was scheduled for ATL.

Dr. Patel said the procedure continues to be a viable option for many patients, but ongoing monitoring of long-term results is needed.

"I think the seizure freedom outcome will be the most interesting factor to follow beyond 1.5 years — the goal is to achieve seizure freedom with the lowest side effects for all our patients," she said. "This information will hopefully enable us to make more individualized plans. Also, it will be interesting (to see) how cognitive deficits compare in patients who achieve seizure freedom to those who do not. It will also be important to look at hemispheric dominance moving forward when looking at cognitive decline."

Despite the deficits found in some patients, the results are not disappointing, said Sarah Bandt, MD, assistant professor of neurological surgery at Northwestern University.

"These results help us understand who is ideally served with the minimally invasive laser technology and who may still need to be considered for a temporal lobectomy," she said.

She cautioned that the study was small and retrospective, and that the bigger picture should not be lost when it comes to the visual field deficits — these deficits should be viewed in the broader context of all patients undergoing the procedure, not just those with post-operative vision concerns.

"Finally, a number of important missing variables limit the interpretation of the neuropsychological findings, including the side surgery was performed on and baseline neuropsychological scores relative to post-operative findings," Dr. Bandt said. "Despite these limitations, I do think this study provides further clarity on the importance of pre-operative MRI findings in patient selection for laser ablation versus temporal lobectomy."

Dr. Patel reported no disclosures. Dr. Bandt has received a stipend from the NFL for consulting work on neurotrauma and from Monteris for travel-related expenses.

LINK UP FOR RELATED INFORMATION

AES Abstract 3.323: Patel A, Dawit S, George M, et al. Long-term outcomes in patients with intractable mesial temporal lobe epilepsy who undergo laser ablation.