Epilepsy surgery indications
Epilepsy surgery is an established safe and effective treatment for selected candidates with drug-resistant epilepsy. In a opinion piece, Hale et al. from the Children’s of Alabama, Great Ormond Street Hospital, Nemours Children’s Hospital outlined the clinical and experimental evidence for selectively considering epilepsy surgery prior to drug resistance. The rationale for expedited surgery is based on the observations that, 1) a high proportion of patients with lesional epilepsies (e.g. focal cortical dysplasia, epilepsy associated tumours) will progress to drug-resistance, 2) surgical treatment of these lesions, especially in non-eloquent areas of brain, is safe, and 3) earlier surgery may be associated with better seizure outcomes. Potential benefits beyond seizure reduction or elimination include less exposure to anticonvulsants (ASM), which may lead to improved developmental trajectories in children and optimize long-term neurocognitive outcomes and quality of life. Further, there exists emerging experimental evidence that brain network dysfunction exists at the onset of epilepsy, where continuing dysfunctional activity could exacerbate network perturbations. This in turn could lead to expanded seizure foci and contribution to the comorbidities associated with epilepsy. Taken together, they rationalize that epilepsy surgery, in carefully selected cases, may be considered prior to drug resistance. Lastly, they outlined the path forward, including the challenges associated with developing the evidence base and implementing this paradigm into clinical care 1).
20% of patients continue to have seizures despite aggressive medical management with antiepileptic drugs AEDs. Many of these patients may be candidates for surgical procedures to control their seizures 2).
Seizure disorder must be severe, medically refractory with satisfactory trials of tolerable medication for at least 1 year, and disabling to the patient. Medically refractory epilepsy is usually considered two attempts of high-dose monotherapy with two distinct AEDs, and one attempt at polytherapy.
The three general categories of patients suitable for seizure surgery have 3):
a) temporal origin: the largest group of surgical candidates (especially mesial temporal lobe epilepsy (MTLE) which is often medically refractory)
b) extratemporal origin
- symptomatic generalized seizures: e.g. Lennox-Gastaut syndrome.
- unilateral, multifocal epilepsy associated with infantile hemiplegia syndrome.
The goal is to eliminate seizures or significantly reduce seizure burden.
In most state-of-the-art epilepsy units, resective epilepsy surgery is currently the standard treatment for intractable epilepsy. Generally, the success rate, defined as a seizure-free status or Engel class I, is between 62% and 71%, as compared to 14% in non-operated cases 4) 5).
Generally, surgery is considered in patients whose seizures cannot be controlled by adequate trials of two different medications. Epilepsy surgery has been performed for more than a century, but its use dramatically increased in the 1980s and ’90s, reflecting its efficacy in selected patients.
Patients with comorbid psychosis and temporal lobe drug-resistant epilepsy may benefit from epilepsy surgery under close psychiatric supervision 6).
Epilepsy surgery is an effective and safe therapeutic modality in childhood. In children with extratemporal epilepsy, more careful interpretation of clinical and investigative data is needed to achieve favorable seizure outcome 7).