The Role of High-Frequency Oscillation Networks in Managing Pharmacoresistant Epilepsy

Persons with pharmacoresistant epilepsy have a higher risk of mortality than those with controlled seizures. Seizure control can be achieved with surgical removal or electrical stimulation of the brain area responsible for generating seizures, but localizing this brain area is difficult and requires different non-invasive tests and, in some cases, an invasive EEG study. Resection or stimulation of the seizure onset zone does not always control seizures, suggesting there are other pathological areas involved in generating seizures. There is a significant body of research on high-frequency oscillations (HFO) associated with normal and abnormal brain function. In the brain with epilepsy, it is believed pathological HFO corresponds with neuronal disturbances in tissue capable of generating seizures, and their removal correlates with seizure control; thus, pathological HFO can be a biomarker of epileptogenic tissue and play an important role in the diagnosis and treatment of epilepsy. However, additional work is needed to better understand the different types of HFO, and the mechanisms generating each, and the parts of the ictal and interictal HFO networks that need to be targeted with therapy to control seizures. This chapter will discuss these issues, the current gaps in knowledge, and demonstrate how measures of HFO networks could be used in the surgical treatment of pharmacoresistant epilepsy.