Abnormal Imaging Indicates Surgery in Intractable Epilepsy

Kate Johnson

June 25, 2013

MONTREAL, Quebec, Canada — Abnormal neuroimaging in children with early medically intractable epilepsy is a strong indication for surgical rather than medical treatment, new research suggests.

"The goal here is to identify which kids who appear medically intractable early in the course of epilepsy will not remit and thus should be considered for early surgery to prevent associated comorbidities of epilepsy," lead author Elaine Wirrell, MD, told Medscape Medical News in an interview. "It is a dilemma as surgery is considered quite invasive and higher risk."

Parents often want to wait and make sure their child doesn't just outgrow the seizures, said Dr. Wirrell, who is professor of neurology at the Mayo Clinic in Rochester, Minnesota, "but this finding is really concrete. We can say if your child is medically intractable and has abnormal imaging the likelihood that they will be seizure free without surgery is less than 9%."

She presented their findings here at the 30th International Epilepsy Congress (IEC).

Early Medical Intractability

The retrospective study included a population-based cohort of 381 children aged 1 month to 17 years, who were diagnosed with new-onset epilepsy in Olmsted County, Minnesota, during a 30-year period (1980-2009) and followed for at least 3 years.

Slightly more than half (54%) of the cohort was male, with a median age at epilepsy onset of 6 years.

A total of 75 patients (19.7% of the cohort) were diagnosed with early medical intractability during the first 2 years after diagnosis of epilepsy, defined as 2 failed antiepileptic medications and ongoing seizures at a frequency of at least every 6 months.

Multivariate analysis showed 3 significant predictors of early intractability, including abnormal neuroimaging (risk ratio [RR], 2.70; P = .0004), abnormal neurologic examination (RR, 1.87; P = .015) and mode of onset, with focal mode of onset less likely to be associated with early intractability compared with generalized (RR, 0.35; P < .0001), she said.

After a median follow-up of 11.7 years, 48 of the 75 patients with early intractability had enduring intractability (defined as having ongoing seizures or having undergone epilepsy surgery), while 27 achieved seizure freedom without surgical intervention.

Multivariate analysis showed that enduring intractability was predicted by only 1 variable: neuroimaging abnormality (RR, 7.0; P =.0006), she reported. Among the 48 patients with enduring intractability, 32 had abnormal neuroimaging, while only 3 of the 27 patients who remitted had this finding.

The findings offer guidance to clinicians and parents who face the dilemma of whether to choose surgery in children with early intractability, Dr. Wirrell told Medscape Medical News.

"We found that children with early intractability who had an imaging abnormality are very unlikely to achieve seizure freedom without surgery — that only occurred in 8.6%. And so in that group early surgical intervention is strongly advised to limit comorbidities of ongoing intractable seizures."

But for neuroimaging to meaningfully predict outcome, it must be done correctly, she added.

"If a child has medically intractable seizures, in other words, they have failed to respond to 2 antiepileptic medications at appropriate doses, that child should be referred to an epilepsy center where chances are they will be imaged using proper technology. It has to be high-quality MRI with a seizure protocol. If it's a standard method done in a small community hospital it's probably not going to be adequate and may miss things," she said.

Useful for Clinicians and Families

Commenting on the findings for Medscape Medical News, Peter Camfield, MD, called them potentially "very useful" to clinicians and families.

"The study needs to be replicated because there are small numbers," said Dr. Camfield, who is professor of neurology and pediatrics at Dalhousie University in Halifax, Nova Scotia, Canada. "But it shows that if you've had 2 years of treatment and you have a lesion on MRI, it just isn't going to go away, so by that time you should decide to proceed with a surgical option. There's no point in waiting longer. That's always the struggle with children and parents who say 'just wait a little longer.'"

One of the things Dr. Wirrell didn't comment on is that the risks from epilepsy surgery in children are "very tiny," Dr. Camfield added. "So you're waiting and waiting for something where the risk of intervention is not that great, while the risk of waiting is probably greater."

He said while some previous studies have suggested predictors of enduring medical intractability, none have been population-based, "which is the tremendous power of the Mayo Clinic study, and the other studies haven't necessarily used MRI so they're not as good, not as robust."

Dr. Wirrell and Dr. Camfield have disclosed no relevant financial relationships.

30th International Epilepsy Congress (IEC). Abstract 001. Presented June 24, 2013.


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