LITT May Trump Standard Surgical Approaches to Epilepsy

Meg Barbor

October 14, 2015

NEW ORLEANS — Open resection has been proven effective for the treatment of mesial temporal lobe epilepsy (MTLE), but there is now growing evidence touting the advantages of laser interstitial thermal therapy (LITT), a less invasive approach.

Epilepsy is diagnosed in an estimated 150,000 Americans each year, or 48 of every 100,000 people. Although about two thirds of patients with epilepsy achieve good seizure control with antiepileptic medications, the remaining one third may be potential candidates for epilepsy surgery. Surgery is most often considered and most frequently successful in patients with mesial temporal lobe epilepsy.

Jason Schwalb, MD, a neurosurgeon at Henry Ford Hospital in Detroit, Michigan, presented current evidence regarding the pros and cons of existing surgical treatment options for MTLE, including standard anterior temporal lobectomy (ATL), selective amygdalohippocampectomy (SAH), and LITT.

He presented the case for each approach here at the Congress of Neurological Surgeons (CNS) 2015 Annual Meeting.

Standard ATL: Pros and Cons

The greatest evidence of benefit for the treatment of MTLE exists with the use of ATL, Dr Schwalb noted.

"This evidence comes from multiple randomized controlled trials and long-standing series with long follow-up that are well designed. In other words, we know it works," he said.

Lateral neocortical resection can be tailored depending on where critical structures are and where the seizures seem to be coming from, he explained.

In addition, standard ATL addresses potential lateral and basal neocortical foci because "sometimes the culprit for the important part of the circuit involved in the epilepsy is not the mesial temporal structures."

However, this procedure is associated with potential neurocognitive and other morbidities.

"Even with what we consider as the 'standard ATL,' there is some heterogeneity, and it is always a balance as to how much lateral tissue to take out to try and maximize the likelihood of the patient being seizure-free," said Dr Schwalb.

"If a patient is still having a seizure a month, even if that's down from 10 a month, they may be happy, but usually you don't make a huge difference in quality of life unless that patient is seizure-free."

SAH: Fewer Cognitive Deficits?

A large variety of methods fall under this technique, including transsylvian, trans-middle temporal gyrus, and subtemporal approaches.

"We think the culprits in most of our patients with temporal lobe epilepsy are the hippocampus, parahippocampus, amygdala, and entorhinal cortex," Dr Schwalb explained. "The promise of this method has been to try and take out less tissue and thereby reduce the risk of postoperative cognitive deficits."

However, multiple studies in the literature have shown that ATL seems to be more effective than SAH at making patients seizure-free.

"Even in cases of radiographic hippocampal sclerosis, where it seems a lot more clear that you're going to get good results from doing a selective approach, you still see some advantage of ATL over selective."

Further, both patients and clinicians are reluctant to undergo more extensive resection if the patient is not Engel 1 (on the Engel Epilepsy Surgery Outcome Scale, class 1 to 4) after selective resection because there are increased difficulty and risk in repeating the surgery.

Finally, the literature does not support decreased cognitive risks after selective surgery. "Part of that may be because patients with uncontrolled epilepsy get worse neurocognitively over time, so it may be a bit of a wash on the neurocognitive side," Dr. Schwalb said.

"So how can we do this in a way that helps neurocognitively but doesn't burn bridges? Through minimally invasive amygdalohippocampectomy, but with the caveat that you generally can't completely ablate the amygdala — we tend to be happy if we get more than 50% of it," he said.

With this modality, a surgeon is able to stereotactically implant a laser probe into the epileptogenic zone via a 3-mm incision and a twist drill. Tissue damage can be monitored in real time with magnetic resonance thermography.

However, it can sometimes be difficult to get a good trajectory with use of this method, and it will not work if the epileptogenic focus is not the amygdala and hippocampus. Also, the cost is high, and this method has yet to stand the test of time, he warned.

"We have to beware that this is a new therapy, just as radiosurgery was a new therapy," said Robert E. Gross, MD, PhD, moderator of the session and MBNA Bowman Chair and Professor at Emory University Department of Neurosurgery in Atlanta, Georgia. "There's a learning curve."

"So that's the point of having these discussions," he told the audience. "And I think it's important that we compare this surgery, LITT, to open standard resections."

Advantages of LITT

Theoretically, this approach should lead to decreased risk for stroke and visual field cuts, as well as decreased length of hospital stay, decreased discomfort, and much faster recovery (when compared with 4 to 6 weeks minimum recovery time after ATL).

"And I think the big thing, unlike after you do a selective, is if you do this and it doesn't work, you can go back and do an ATL and you're not dealing with a scarred region — it's no more technically difficult than going in fresh," Dr Schwalb said. "And, in general, the patients are not averse to doing that because they don't have all the pain from the cutting of the temporalis muscle and from the recovery from the first surgery."

The literature has also shown neuropsychological advantages of LITT when compared to ATL or selective resection and also suggests that it may be an option for patients with dominant temporal lobe epilepsy and normal (or near-normal) verbal memory.

"I think one of the most significant promises is that this is potentially an option for a patient who might not even be previously considered for SAH or ATL," said Dr Schwab.

Dr Schwalb is co-investigator, National Institutes of Health/National Institute of Biomedical Imaging and Bioengineering 1 R01 EB013227-01A1: Decision Support System for Temporal Lobe Epilepsy (principal investigator: Hamid Soltanian-Zadeh, PhD). Visualase and Monteris systems are Food and Drug Administration approved to necrotize or coagulate soft tissue in neurosurgery. Dr Gross consults for Deep Brain Innovations, Medtronic, MRI Interventions, Neurospace, St. Jude Medical Corporation, and Visualase.

Congress of Neurological Surgeons (CNS) 2015 Annual Meeting. Presented September 29, 2015.

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