Overview of Seizures
Management of Different Types of Electrical Discharge from the Brain
May 9, 2009
A seizure is defined as an abnormal electrical discharge from the brain that results in neurological signs, such as involuntary movement or behavioral change. Approximately 9% of people in the United States have one or more seizures throughout life. A term related to seizure is epilepsy, which refers to the tendency to have recurrent spontaneous seizures that are not due to reversible causes.
Causes
Many conditions can cause seizures, including but not limited to the following:
- Impaired blood flow to the brain (e.g., stroke)
- Low oxygen delivery to the brain (e.g., carbon monoxide poisoning)
- Central nervous system infection (e.g., an abscess in the brain)
- Tumors
- Traumatic brain injury
- Fever (febrile seizures)
- Drug toxicity (e.g., cocaine toxicity)
- Withdrawal syndromes (e.g., alcohol withdrawal)
- Metabolic abnormalities (e.g., low blood sodium)
- Congenital conditions (e.g., malformations of the brain)
Seizures in children are often due to congenital conditions or fever but may also have an unknown cause (idiopathic). For adults, common causes of seizures include tumors, strokes, alcohol withdrawal, and traumatic brain injury.
Classification
Seizures are classified into two broad categories according to their pathophysiology and clinical manifestations:
- Generalized Seizures: Generalized seizures occur as a result of abnormal electrical discharge through the brain. This results in loss of consciousness plus sudden loss of muscle tone (atonic seizure), brief muscle contractions (myoclonic seizure), continuous muscle contraction (tonic seizure), continuous muscle contraction followed by a series of rapid muscle contractions (tonic-clonic seizure, formerly called a grand mal seizure), or brief loss of attention (absence seizure, formerly called a petit mal seizure).
- Partial Seizures: In contrast, partial seizures occur with abnormal electrical discharge originating from one part of the brain only, although they can evolve into generalized seizures. These seizures are characterized by motor or sensory disturbances that depend on which part of the brain is the seizure focus and may or may not involve loss of consciousness (simple partial seizure or complex partial seizure, respectively).
Evaluation
When evaluating a patient who just had a seizure, the physician must first determine that the patient did indeed have a seizure and not loss of consciousness alone. From there, he or she attempts to pinpoint the cause of the seizure, if possible, through a patient history and physical examination. If necessary, further evaluation can entail imaging with computed tomography (CT) or magnetic resonance imaging (MRI) to rule out causes within the brain and electroencephalography (EEG) to assess brain wave patterns that may suggest an epileptic seizure.
Treatment
In general, the treatment of seizures involves addressing the underlying cause, if possible, and controlling the seizures directly. The latter is achieved with medications, which include but are not limited to lorazepam (Ativan), phenytoin (Dilantin), valproic acid (Depakote), and topiramate (Topamax). Such drugs are given immediately to abort the process and in the long term to prevent another seizure. If at least two anti-seizure drugs are ineffective and the seizures are partial seizures, surgery to excise the seizure focus in the brain may be considered.
Prognosis
Seizures are often adequately addressed with appropriate treatment. In general, at least two-thirds of patients have complete cessation of seizures or significantly reduced frequency of seizures following treatment.
References
 |
