Mortality, Morbidity Low After Surgery for Intractable Epilepsy

Pauline Anderson

March 03, 2011

March 3, 2011 — Anterior temporal lobectomy (ATL) for intractable temporal lobe epilepsy (TLE) is associated with a low morbidity rate and no mortality during a 16-year period, a new study has found.

The retrospective study found an 8% incidence of morbidity after the surgery, a rate that likely includes transient complications. The risk for postoperative morbidity increased with more medical comorbidities and also with increasing patient age and lack of private insurance.

The results should alleviate concerns of some neurologists that this surgery may be too risky, said lead study author, Shearwood McClelland III, MD, from the Department of Neurological Surgery at Boston University School of Medicine in Massachusetts and the Program in Health Disparities Research at the University of Minnesota in Minneapolis.

"Given that this study is over a long period time, that it's not just 1 surgeon's experience but rather a sample over the entire US, and that it's pretty consistent with what surgeons have already published in their 1- or 2-center series, I think that it will help neurologists have a better look at the facts behind the surgery."

The study was published online February 14 in the Archives of Neurology.

Postoperative Complications

Previous research has shown surgery eliminates seizures in 60% to 80% of TLE patients compared with only 10% of patients who receive additional medications instead of surgery, said Dr. McClelland.

The current analysis used hospital discharge data from the Nationwide Inpatient Sample (NIS), which represents about 20% of all inpatient admissions to nonfederal hospitals in the United States. The NIS contains data on all patients discharged from sampled hospitals and can be used to obtain the annual total volume of specified procedures at individual hospitals. Researchers searched the database to identify admissions for temporal lobectomy for intractable TLE on patients 18 years or older from 1988 to 2003.

The study included 736 patients who received ATL at 190 hospitals. Of these, 8% had postoperative complications, including neurologic complications (2.7%), transfusion of packed red blood cells (2.3%), and hematoma (1.2%). There was no mortality, and no patients had a deep vein thrombosis or pulmonary embolism.

Some of these complications could be transient, Dr. McClelland noted. "If you had an infection that was treated with antibiotics and it went away in a week, that would still count as a complication."

The incidence of postoperative morbidity directly correlated with increasing patient comorbidity, the study authors report. The complication rate was 7.8% among those with no comorbidities compared with 25.0% in those with 3 comorbidities. Most patients were relatively healthy: 82.3% had no comorbidities, only 0.5% had 3 comorbidities, and no patient had more than 3 comorbidities.

The study also found a 4% rate of adverse discharge disposition, defined as discharge to rehabilitation before going home, and a 10.8% overall morbidity, which included postoperative morbidity and/or adverse discharge disposition. Of the 677 patients with available discharge data, 3 needed short-term rehabilitation and 24 required long-term rehabilitation.

The complication rate reported in the published literature ranges from about 7% to about 20%, said Dr. McClelland.

In this study, race, sex, and hospital volume had no effect on the rate of complications. Private insurance, however, was associated with significant decreases in both postoperative morbidity and adverse discharge disposition.

Table 1. Effect of Private Insurance on Postoperative Morbidity and Adverse Discharge Disposition After Epilepsy Surgery

Factor Odds Ratio (95% CI) P
Postoperative morbidity 0.52 (0.28 – 0.98) .04
Adverse discharge disposition 0.31 (0.12 – 0.82) .02

CI = confidence interval

Increasing age, conversely, was associated with both increased postoperative morbidity and adverse discharge disposition.

Table 2. Effect of Increasing Age on Postoperative Morbidity and Adverse Discharge Disposition After Epilepsy Surgery

Factor Odds Ratio (95% CI) P
Postoperative morbidity 1.04 (1.01 – 1.07) .03
Adverse discharge disposition 1.08 (1.02 - 1.13) .004

CI = confidence interval

Previous research showed that patients with private insurance are more likely to get surgery. "Unlike race, which predicted disparities in getting surgery but not in outcomes afterwards, private insurance predicted disparities not only in getting surgery but also in outcomes," said Dr. McClelland.

Dr. McClelland believes a number of factors contribute to these low morbidity rates. "Number 1, we know what we're going after; number 2, it's a relatively short procedure; number 3, compared to large tumor surgeries, there's not a lot of brain being taken out; and number 4, the patients are relatively healthy."

In 2001, a Canadian group demonstrated superiority of this surgery compared to medical therapy for patients with intractable epilepsy in a randomized controlled trial (Wiebe S, et al. N Engl J Med. 2001;345:311-318). In that study, there was no mortality in the surgery group, whereas 3% of the medical group died.

Reluctance to Refer

Even with this class 1 evidence, some neurologists are reluctant to refer patients with TLE in whom 2 drug trials have failed to surgery. "A lot of these neurologists trained in the 1960s, '70s, and even early '80s, when the surgical techniques weren't as advanced as they are now, so surgery was a lot riskier then," said Dr. McClelland.

Asked for comment on these new results, Dennis D. Spencer, MD, chair of neurosurgery at Yale University, New Haven, Connecticut, and director of the Surgery Epilepsy Program, who also sits on the board of the American Epilepsy Society, pointed out that the study doesn't indicate the transient nature of the complications experienced by the patients or how they may have affected quality of life.

"We only have limited knowledge about which of these issues had long-term consequences; it appears that most of them are short term and transient," he said.

Some postoperative morbidity, for example, transfusions and hematomas (which are often an accumulation of blood under the bone), are relatively common surgical complications, noted Dr. Spencer.

The infection rate in the study, at 0.8%, could be misleading, he added. "Most infections are skin and bone infections, which don't have any CNS [central nervous system] long-term consequences."

He suspects there is a fair amount of overlap or duplication in the list of complications. "For instance, the incidence of hydrocephalus is 0.4% and then the incidence of ventriculostomy is 0.1% and postoperative infection is 0.8%. That must be the same person. Often, the person who gets an infection then has to have a catheter placed for drainage and then develops hydrocephalus afterwards."

The 3 patients sent for short-term rehabilitation "probably had a stroke from the surgery" that required physical therapy, he added.

He's concerned that physicians will be alarmed by an overall complication rate of over 10%. "If I was going to get my hernia repaired and someone told me there was a 10% chance of significant long-term morbidity, I'd live with the hernia."

I'm hoping people will understand that this operation has been around for long time and is the only epilepsy surgery that had class 1 evidence-based outcome.

At his center, physicians quote a much lower post-ATL morbidity rate of 1% to 2%.

"I'm hoping people will understand that this operation has been around for long time and is the only epilepsy surgery that had class 1 evidence-based outcome."

Dr. Spencer noted that the code in the database for medically intractable epilepsy of temporal lobe origin "can be very, very broad" and include a wide range of operations other than standard surgical temporal lobe procedure.

The improved outcome of patients with private insurance noted in the study is a "surprise" and could be linked to other risk factors, such as age and comorbidity, said Dr. Spencer, who added that insurance status is not a factor in his own institution.

"Someone may not get into the system until they're much older because they don't have insurance, and then their morbidity goes up because of age, or if they're obese or have cardiovascular disease," he said. "It would be a big red flag if this study is saying that if you have insurance we're going to take care of you better in the operating room than if you don't have insurance. That just doesn't happen."

The study authors have disclosed no relevant financial relationships.

Arch Neurol. Published online February 14, 2011.

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