**1. Introduction**

Epilepsy is a brain disorder characterized by brief disturbances in the normal electrical function of the brain resulting in seizures; 35% of adults with active epilepsy have seizures that are not seen by a neurologist or an epilepsy specialist [1].

Epilepsy is one of the most common chronic neurologic disorders with a worldwide prevalence of approximately 1.2% [2]. Epilepsy contributes to up to 25% of the global burden of neurological disease, and many neurological diseases are associated with seizures and epilepsy [3].

Recent data indicate that epilepsy mortality rates are rising significantly [4]. These data have generated significant concern from stakeholders and advocacy groups that the increase in epilepsy mortality may represent a failure to effectively treat epilepsy and prevent premature death [5].

Only 64% of patients with new-onset seizures are seizure-free by their third antiepileptic drugs (AED) [6]. Thus, more than 35% of patients continue to have seizures and become recognized as refractory seizure patients.

The pre-surgical evaluation should result in a clear understanding of whether surgery can be undertaken and its potential benefit [7].

Neuroimaging developments with the introduction of magnetic resonance imaging (MRI), functional (fMRI), fluourodeoxyglucose F18 positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetoencephalography (MEG) have facilitated the selection of patients for surgery, also reducing the number and severity of complications [8, 9]. Neurophysiological tests include invasive and noninvasive procedures and define the epileptogenic zone in a specialized center. Epilepsy surgery should be recommended through a multidisciplinary team [5].

In pharmacoresistant (PR) patients, epilepsy surgery must take into consideration the chance of seizure freedom and the adverse long-term effects of uncontrolled seizures [10]. Epilepsy surgery is underutilized even in developed countries because many physicians do not recognize that a treatable syndrome exists and in developing countries because of lack of resources or because many physicians do not recognize that a treatable syndrome exists [5].

Developments made in surgical techniques have significantly increased the effectiveness and safety of these techniques as such techniques have been demonstrated to improve seizure control/freedom outcomes [11] and increase patients' life span [8] by reducing the number and severity of complications [8, 9].

## **2. Refractory seizure**

One percent of the world's population has active epilepsy, 30–40% of people with epilepsy have a seizure that is uncontrolled by medication [1], which accounts for 80% of the cost of epilepsy in the United States [12].

PR epilepsy is, therefore, a major health concern for patients, their families, and for the society. Treatment aim for epilepsy is seizure freedom with no side effects, as soon as possible. Full-service epilepsy centers are staffed by a multidisciplinary team consisting of neurologists, epileptologist, neurosurgeons, neuroradiologists, clinical neurophysiologists, neuropsychologists, psychiatrists, social workers, and nurses skilled in the management of epileptic seizures and their consequences [13]. These approaches permit recognition of true epileptic seizures and their causes, diagnosis of specific seizure types and epilepsy syndromes, and determination of which patients are truly FRs and might be candidates for surgical therapy.

Apparent pharmacotherapy failure does not necessarily mean that standard AEDs will not work. Alternative causes are seizures that are not epileptic, misdiagnosis of the seizure type or epilepsy syndrome, inappropriate use of AED such as inadequate doses or drug interactions and lifestyle issues, such as drug abuse, alcohol binging, stress, and sleep deprivation. Epilepsy centers have the ability to utilize specialized pharmacologic approaches, including enrollment in clinical trials of experimental anti-seizure drugs, to provide alternative treatments other than surgery,

The term "PR epilepsy" can no longer be taken literally, as there are now so many anti-seizure drugs that it would take a lifetime to try all of them alone and in combination in any given patient.

There are several reasons for PR, and research to clarify underlying mechanisms is important for the future development for more effective treatments [14].

*Recent Advances in Epilepsy Surgery DOI: http://dx.doi.org/10.5772/intechopen.107856*

Concerning the diagnosis of PR patients, the International League Against Epilepsy (ILAE) has proposed, as a verifiable hypothesis: "That PR is defined as failure of adequate trials of two tolerated, appropriately selected, and used antiepileptic drug schedules (monotherapies or in combination) to achieve sustained seizure freedom, which is defined as sustaining seizure freedom for a period 3 times the longest inter-seizure interval or 1 year whichever is longer" [15].
