October 14, 2011 — For many patients with refractory focal epilepsy, neurosurgery can mean freedom from seizures, according to results of what is believed to be the largest and longest prospective study of epilepsy surgery outcomes ever conducted.
John S. Duncan, FMedSci, FRCP, professor of neurology, University College London Institute of Neurology, United Kingdom, and medical director, Epilepsy Society, worked on the study.
The results, published online October 15 in The Lancet, show that epilepsy surgery “can be life changing and curative,” Dr. Duncan said.”What is unique about this study,” he told Medscape Medical News, “is the comprehensive, annual long-term follow-up in our program going back over 19 years, and continuing (an advantage of the UK National Health Service), giving 5241 patient-years of follow-up.”
Practice-Changing?
The patients in the study had epilepsy for a median of nearly 21 years before surgery. The new data suggest that patients should be referred sooner, the authors say. “The inference is that surgery should be considered for focal epilepsy if 2 to 3 antiepileptic drugs have not controlled seizures, and this will usually be evident in 2 to 3 years,” Dr. Duncan said.
The authors of a linked comment agree. “In view of the long-term results of surgery shown, clinical practice needs to change with the early referral of appropriate patients,” write Ahmed-Ramadan Sadek, MD, and William Peter Gray, MD, from the University of Southampton, United Kingdom.
The study cohort included 615 men and women who had epilepsy surgery at the National Hospital for Neurology and Neurosurgery in London between February 15, 1990, and October 30, 2008.
There were 497 anterior temporal resections, 40 temporal lesionectomies, 40 extratemporal lesionectomies, 20 extratemporal resections, 11 hemispherectomies, and 7 palliative procedures (eg, corpus callosotomy, subpial transaction). The patients were followed-up annually for a median of 8 years, with a range of 1 to 19 years.
The investigators report that 2 years after surgery, nearly two thirds of patients were seizure-free, based on “usually cited criteria” of entirely seizure-free or simple partial seizures (SPS) only. At 5 and 10 years, about half of the patients continued to be seizure-free by this definition.
Table. Percentage Seizure-Free or With Simple Partial Seizures Only After Surgery
| Follow-Up | % (95% Confidence Interval) |
| 2 years | 63 (59 – 67) |
| 5 years | 52 (48 – 56) |
| 10 years | 47 (42 – 51) |
At each annual review, 68% to 73% of patients were seizure-free or had SPS only; 40% of patients were completely seizure-free throughout follow-up.
Predictors of Outcome Emerge
Anterior temporal resection was associated with a higher probability of seizure freedom than resection in other areas of the brain.
An initial and longer period free from seizures after surgery was the strongest predictor of good long-term outcome (seizure freedom). Conversely, in patients with prolonged postsurgery seizure activity, the likelihood of seizure remission was decreased.
The researchers also found that although the overall proportion of patients remaining seizure-free was “fairly stable,” every year there was a 3% to 15% change in seizure status, either from seizure-free to having seizures or from continuing seizures to seizure freedom.
The study also found that patients who continue to experience SPS in the first 2 years after surgery have a greater likelihood of subsequent seizures with impaired awareness than those with no SPS (hazard ratio, 2.4; 95% CI, 1.5 – 3.9). “[P]revious studies have not reported this finding,” the authors say.
This information might affect the decision to taper or continue antiepileptic drug therapy, they say. Most patients who were seizure-free after surgery chose to continue receiving an antiepileptic drug. Only about a quarter of seizure-free individuals had discontinued their antiepileptic medication at latest follow-up.
The researchers also found evidence that, for patients who continue to have seizures after surgery, introducing a previously untried antiepileptic drug may lead to remission.
No Worsening of Epilepsy
Importantly, note the researchers, no patient had substantial worsening of epilepsy after surgery.
Clinically relevant morbidity caused by the surgical procedures consisted of “46 superior quadrant visual field defects (8% of temporal lobe procedures); 28 (5%) wound infections needing antibiotics; three (<1%) hemipareses; 15 (2%) cases of frontalis muscle weakness; six (1%) cases of dysphasia; 19 (3%) cerebrospinal fluid leaks needing resuturing; and one deep venous thrombosis needing anticoagulation.”
This study, Dr. Duncan commented, provides long-term follow-up of epilepsy surgery, which is required to give “realistic expectations.” He emphasized that the evaluation of patients and surgery are “complicated and need a well-functioning multidisciplinary team.”
In their comment, Dr. Sadek and Dr. Gray say this study “validates the long-term effectiveness of epilepsy surgery showing that over 50% of all patients are rendered continuously long-term seizure free.” These data “will be useful for counselling patients and guiding their physicians,” they conclude.
The study was supported by the UK Department of Health National Institute for Health Research Biomedical Research Centres, Epilepsy Society, Dr. Marvin Weil Epilepsy Research Fund. Dr. Duncan has been consulted by and received fees to his institution for lectures from Eisai, GE Healthcare, Pfizer, GlaxoSmithKline, Sanofi- Aventis, and UCB, as well as departmental and grant support from MedTronic, Cyberonics, and VSM MedTech. A complete list of disclosures for study authors is listed with the original article. Dr. Sadek and Dr. Gray have disclosed no relevant financial relationships.
Lancet. 2011;378:1360-1362,1388-1395.
Source: Medscape News Today
