What is a seizure? Seizures are an important cause of visits to an emergency department (ED), accounting for millions of visits annually worldwide. The billions of neurons in the human brain generally communicate with each other via small electrical and chemical signals. However, when networks of neurons function abnormally, they can produce much larger, synchronous, electrical discharges. In general, these highly synchronized discharges are abnormal and when spontaneous and sustained highly synchronous discharges occur, they disrupt otherwise normal brain activity, creating an electrical seizure in the brain. Because this electrical seizure disrupts normal brain activity, a person can experience involuntary experiential or behavioral changes that are the clinical manifestations of a seizure. This chapter will focus on patients presenting with clinical manifestations of seizures. Additional information about seizures occurring alongside symptoms due to other conditions can be found in other chapters of this book. In general, these involuntary experiential or behavioral changes are highly dependent on the functions of the brain that are located where the abnormal discharge starts and over the area where the abnormal discharge eventually spreads . For example, a complex partial seizure of mesial temporal onset may begin with the patient experiencing a sensation of an unpleasant smell. As the seizure progresses and the abnormal electrical activity spreads within the brain, patients may stare and have abnormal involuntary, often repetitive, movements of their mouth or hands. Seizures with onsets in different areas of the brain will have different manifestations. A list of common clinical manifestations of seizures, along with their suspected regions of onset, can be found in Table 8.1.
ASJC Scopus subject areas