9.7 Seizures and Epilepsy
A seizure is abnormal transient discharges of neurons within the brain that are sudden, excessive, and uncontrolled. During a seizure, many neurons send signals at the same time, much faster than normal. This surge of excessive electrical activity may cause involuntary movements, sensations, emotions, and/or behaviors. The disturbance of normal nerve cell activity may cause a loss of awareness. Some people recover immediately after a seizure, while others may take minutes to hours to feel like themselves again. During this time, they may feel tired, sleepy, weak, or confused.[1]
Most seizures are idiopathic, with no known cause. Seizures can also be caused by other medical conditions, such as a brain tumor, high fever, or hyponatremia. Epilepsy is a chronic disorder that is defined by at least two unprovoked seizures occurring at least 24 hours apart and in which groups of nerve cells, or neurons, in the brain sometimes send the wrong signals and cause recurrent, unpredictable, and unprovoked seizures.
Status epilepticus refers to a seizure lasting more than five minutes or two more sequential seizures without full recovery of consciousness between the seizures. Seizures lasting more than five minutes damage neurons and are unlikely to end on their own, requiring immediate emergency medical care.[2]
Pathophysiology
Seizures are caused by an abnormality in electrical neuron activity, an imbalance of the neurotransmitter GABA, or a combination of both conditions. When there is an imbalance between inhibition and excitatory conditions within the CNS, a seizure occurs.
View a supplementary YouTube video[3] on epilepsy from the Mayo Clinic: What is epilepsy? A Mayo Clinic expert explains.
Types of Seizures
Seizures are divided into three broad categories called partial (focal), generalized, and unclassified seizures. See an illustration of partial (focal) and generalized seizures in Figure 9.20.[4] Each of these categories will be further discussed in the following subsections.
Partial Seizures
Partial seizures, also known as focal seizures, occur within one cerebral hemisphere of the brain. Partial seizures are further subdivided into two main classes called complex partial seizures and simple partial seizures. In some instances, a partial seizure can develop into a generalized tonic, clonic, or tonic-clonic seizure. Partial seizures are more common in adult clients and are generally less responsive to medical treatment than other types of seizures.
- Complex partial seizures: These seizures often occur in the temporal lobe and may be called psychomotor seizures due to the function of this part of the brain. Semi-coordinated, repetitive motor movements occur, and loss of consciousness may occur for one to three minutes. Clients are unaware of their environment and may wander at the beginning of the seizures. In the postictal period (time after the seizure), clients may have amnesia.
- Simple partial seizures: The client rema