According to the survey, there are more than 6 million patients with epilepsy in China, with 65-70 million new patients each year. 70%-80% of these patients can have their seizures completely controlled or significantly reduced through standardized and reasonable antiepileptic drug treatment, but 20%-30% of patients belong to drug-refractory epilepsy, and these patients suffer from recurrent seizures as well as drug side effects, and also suffer from This group of patients suffers from recurrent seizures and side effects of medication, and also suffers from a huge loss of quality of life and social opportunities as a result. In the past 20 years, with the in-depth understanding of epilepsy and the great progress in epilepsy surgery technology, surgery has become an important treatment for drug-refractory epilepsy and is gaining attention.
1. The concept of drug-refractory epilepsy
The definition of drug-refractory epilepsy has not yet been fully unified, and other concepts with similar meanings include “intractable epilepsy”, “drug-resistant epilepsy”, and “refractory epilepsy”. At present, the definition of “intractable epilepsy” is more widely accepted in China, which means that the epilepsy is still difficult to control after more than 2 years of regular treatment with 2 suitable antiepileptic drugs (except for some special types of epileptic syndromes and children), and the seizures are still frequent, with an average of more than 1 seizure per month, which seriously affects daily life and work.
2. Types of epilepsy suitable for surgical treatment
Clinical data show that if monotherapy does not result in good seizure control, it is unlikely that further application of 2 or 3 antiepileptic drugs will completely control the seizures. If formal treatment with 2 drugs fails, the likelihood of achieving success with a 3rd drug is less than 10-15%. Therefore, the timely intervention of surgical treatment is important. The effectiveness of surgical treatment of epilepsy has been objectively demonstrated in patient populations that meet the indications for surgery. Moreover, as research on epilepsy progresses, it is recognized that some epilepsies are refractory from the beginning, such as West syndrome, Lennox-Gastaut syndrome, Sturge-Weber syndrome, Rasmussen encephalitis, tuberous sclerosis, hemimegalencephaly, and medial temporal lobe epilepsy syndrome, etc. For these drug-refractory epilepsies that can be anticipated as For these seizure types that are predictably drug-refractory, early surgical intervention is increasingly advocated, and surgery should not be used only as a “last resort”, without waiting more than 2 years for drug treatment. A strict and accurate grasp of the indications for surgery is a guarantee of surgical efficacy and a prerequisite for evaluating surgical efficacy. At present, the common types of epilepsy suitable for surgical treatment are.
(1) Temporal lobe epilepsy
(1) Temporal lobe epilepsy is divided into medial temporal lobe epilepsy and lateral temporal lobe (neocortical) epilepsy. Medial temporal lobe epilepsy is mostly associated with hippocampal sclerosis, and most of the seizures are preceded by aura, which often manifests as “rising gas sensation” (discomfort in the abdomen and gradually rising to the chest and throat), swallowing, smacking, chewing, pill rolling, flapping, groping, bowel sounds, belching, facial redness, pallor, respiratory arrest, pupil dilation, fear, smell hallucination, taste hallucination, etc.
(2) Extra-temporal lobe epilepsy
Extra-temporal lobe epilepsy includes frontal lobe epilepsy, parietal lobe epilepsy, occipital lobe epilepsy, etc. The clinical manifestations are diverse, and the pathological changes often involve motor, sensory, language and other cortical functional areas, and often involve more than one brain lobe. The main surgical approaches are resection of the epileptogenic focus, corpus callosotomy, multiple subchondral transection, vagus nerve stimulation, and deep brain electrical stimulation.
(3) Childhood catastrophic epilepsy syndrome
Childhood catastrophic epilepsy syndrome is a group of epilepsy syndromes that occur specifically during childhood and are characterized by frequent and severe seizures that are poorly controlled by medication and eventually lead to developmental delay and intellectual disability in children. Treatment of epilepsy in children should take into account not only seizure control but also the preservation of brain development and function. Therefore, based on the impact of frequent seizures on the intelligence and development of children and the plasticity of the developing brain in children, an increasing number of scholars advocate early surgical intervention for childhood catastrophic epilepsy syndromes or drug-refractory epilepsy.
①West syndrome
It is the most common form of childhood catastrophic epilepsy, usually presenting with a “triad” of spastic seizures (typical seizures include head nodding, bilateral upper limb hugging movements, and many seizures in a series), psychomotor retardation, and high wave amplitude dysrhythmic EEG. For limited cortical foci located in non-functional areas, excisional surgery is often advocated. For those with extensive epileptogenic foci or independent foci bilaterally, corpus callosotomy can be used.
Lennox-Gastaut syndrome
Lennox-Gastaut syndrome accounts for 4.2-10.8% of childhood epilepsy, with onset from 4 months to 11 years of age, and is more common before 4 years of age. The syndrome is characterized by multiple forms of seizures, with two or more seizure forms occurring simultaneously, mainly tonic, atonic, and atypical aphasic seizures. 20-60% of children have intellectual disability at onset, and 75-90% have intellectual disability several years after onset. Half of the children have behavioral abnormalities. Treatment with conventional antiepileptic drugs is usually ineffective. Aggressive surgical treatment should be considered for those who are suitable for surgery, mostly by corpus callosotomy, which can be completely controlled or improved in 50% of patients.
(iii) Rasmussen’s encephalitis
Rasmussen’s encephalitis is an epidemic disease of unknown etiology that starts in childhood, most often between the ages of 1 and 12 years, with lesions mainly involving one hemisphere. Children show progressive worsening of neurological symptoms, with hemiplegia and intellectual disability in the late stages. The hemisphere resection on the side of the lesion is the only effective way to control epilepsy.
5) Hemilateral macrocephaly
It is a rare developmental malformation of the brain with clinical manifestations such as mental retardation, hemiparesis, hemianopsia, and intractable seizures (mostly partial seizures secondary to generalized seizures). The diagnosis mainly relies on clinical manifestations and neuroimaging. There is resistance to antiepileptic drugs and all develop drug-refractory epilepsy in the later stages of treatment. On the basis of comprehensive evaluation, if the diseased hemisphere has lost normal function and is partially or fully compensated by the healthy hemisphere, surgery should be performed as early as possible, and hemispherectomy, corticotomy, partial cerebral cortical resection, etc. may be performed.
(4) Symptomatic epilepsy
Epilepsy secondary to various types of brain tumors, cerebrovascular disease, traumatic brain injury, cerebral parasitism, encephalitis, cortical dysplasia, and tuberous sclerosis is usually amenable to surgical treatment. It has been shown that surgical procedures for patients with definite imaging changes can achieve more satisfactory results.