Neurosurgery for refractory focal epilepsy leaves half of adults free of seizures for up to 10 years, a prospective study showed.
Freedom from disabling seizures was 52% at five years and 47% at 10 years, John S. Duncan, MD, of the Institute of Neurology at University College London, and colleagues found. The strongest predictor of a good long-term outcome was an initial period of freedom from even the simple partial seizures that don’t impair consciousness, they reported in the Oct. 15 issue of The Lancet.
But only 28% of those who were seizure-free long term had discontinued antiepileptic medication and could thus be considered cured, the group noted.
Prior studies have tended to overestimate the number of patients who remain seizure-free after surgery, noted Ahmed-Ramadan Sadek, of Southampton University Hospitals, and William Peter Gray, MD, of the University of Southampton, England.
Surgery makes patients seizure-free
Yet the fact that more than half of patients remain continuously seizure-free long term validates the surgery, which has seen a resurgence in the past two decades, they pointed out in an accompanying editorial. A change in clinical practice to refer appropriate patients earlier for possible surgery was recommended by both the researchers and editorialists.
The study followed 615 adults prospectively with annual follow-up for a median of eight years after surgery for refractory focal epilepsy.
These surgeries predominantly were anterior temporal resections (497 of 615). The rest were divided among temporal or extratemporal lesionectomies, extratemporal resections, and hemispherectomies along with a handful of palliative corpus callosotomy and subpial transection procedures.
Seizure recurrence was more likely after extratemporal resection (hazard ratio 2.0,P=0.02) but not after lesionectomies, compared with anterior temporal resection.
Patients free from even simple partial seizures in the first two years after surgery were 2.4-fold more likely to remain free of more serious seizures long term (95% confidence interval 1.5 to 3.9).
The longer a person remained seizure-free, the less likely relapse was. While remission was also less likely the longer a person continued with seizures after surgery, there was some room for optimism.
Patients not rendered immediately seizure-free or with a short-lived relapse, 15% eventually gained remission and notably, no patient had a substantial worsening of epilepsy after surgery.
The overall proportion of seizure-free patients remained fairly stable at about 70% at any point, but 3% to 15% of patients shifted status in a typical year. Of the 93 late remissions, 18 (19%) occurred after introducing a previously untried anti-epileptic drug.
The researchers cautioned that their study had small numbers of patients in some surgical type groups, and surgical type was not randomly assigned. Also, small numbers and the observational design of the study limited conclusions on use of anti-epileptic drugs, they added, though noting that “if seizures continue after surgery, new drugs could be considered.”
The results are likely generalizable to patients treated at other major epilepsy surgery centers because procedures and process of surgery are similar, Duncan’s group suggested.