Minimal Resection Effective for Some Patients With Epilepsy

Nancy A. Melville

January 03, 2013

San Diego, California — Smaller lesionectomy resections in the surgical treatment of seizures appear to be just as effective as larger resections in select children, sparing patients the functional and developmental deficits associated with the larger resections, a new study suggests.

Lesionectomy, or removal of abnormal lesions seen on MRI, has been well documented to control seizures for the majority of patients with epilepsy; however, when patients with intractable epilepsy have normal MRI findings, the procedure is more complicated, lead author Prasanna Jayakar, MD, director of the Neuroscience Center and chairman of the Brain Institute at Miami Children's Hospital in Florida, told Medscape Medical News.

"In children with normal MRIs, surgeries are guided by functional abnormalities that are often diffuse and lead to large resections involving an entire lobe or multiple lobes," he said. Although large resections are better for controlling seizures, they may involve critical regions and risk functional outcomes.

To determine whether such large resections can be safely avoided, Dr. Jayakar and his team developed a minimally resective strategy, dubbed "functional lesionectomy," in which integrated data from various modalities helps identify the "epicenter" of functional abnormalities for removal.

Their early findings with this novel technique offer important evidence suggesting that the approach does not compromise outcomes.

"Generally most centers believe that children with normal MRI require large resections in order to achieve seizure control," he said. "To our knowledge this is the first such report of restricted resections in this patient population."

Their findings were presented here at the American Epilepsy Society (AES) 66th Annual Meeting.

Intractable Partial Epilepsy

The researchers reported on the outcomes of 25 children with MRI-negative, intractable partial epilepsy who underwent focal corticectomies at Miami Children's Hospital between 2005 and 2011.

The modalities used to identify the epileptogenic region included 3-dimensional electroencephalography (EEG) source localization, single-photon emission computed tomography (SPECT), positron emission tomography (PET), and invasive EEG data that used co-registration software.

The results showed seizure freedom in 3 of 7 (43%) children with type I focal cortical dysplasia, 7 of 12 (58%) children with type II focal cortical dysplasia, and 3 of 6 (50%) with mild malformations of cortical development.

Resections were considered complete in 7 patients and incomplete in 18; however, the outcomes were unrelated to completeness of resection, suggesting that smaller resections did not worsen outcomes.

A greater number of convergent functional modalities was associated with improved outcome, and all 3 of the histopathologic classes were seen in each Engel outcome class.

Most children with Engel class IV outcomes showed data convergence of fewer functional modalities than that seen in almost all children in more favorable outcome classes.

In all cases, the corticectomies were convergent with scalp EEG, and 11 of 12 cases used 3-dimensional EEG for the localization of scalp interictal data.

Ictal SPECT scans showed convergent, focal hyperfusion in 10 of 15 patients, and 12 of 17 patients who underwent PET had convergent regions of hypometabolism. Two had highly localized, convergent hypermetabolic areas.

Intraoperative electrocorticography showed convergent interictal or ictal discharges in 23 children, and 24 experienced ictal onset in corresponding regions in extraoperative subdural monitoring.

Spark Interest

According to epilepsy expert Sanjeev Kothare, MD, the functional lesionectomy concept is indeed in its early stages, but the approach's potential should spark interest.

"As of now, small is not good because we believe that one should resection the entire epileptogenic zone for seizure freedom, [but] there may be a role for this approach in select cases," said Dr. Kothare, senior epileptologist at Boston Children's Hospital and associate professor at Harvard Medical School in Massachusetts.

"If proved by other centers and by a larger series of patients, it would mean that minimal resection of the seizure onset zone could help in reduction of seizure burden, and improved quality of life, without irreversible damage to eloquent cortex and irreversible loss of function, such as vision, language, motor and memory."

The study did not receive outside funding. Dr. Jayakar and Dr. Kothare have disclosed no relevant financial relationships.

American Epilepsy Society 66th Annual Meeting. Abstract 1.280.

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