Category: Fundamentals Myoclonic seizures are sudden, brief, shock-like muscular contractions. They may be generalized or they may be confined to the face and trunk muscles, to one or more of the extremities, or to individual muscle groups.
Category: Fundamentals Atonic seizures (drop attacks or astatic seizures) are characterized by a sudden loss of muscle tone, which may be only fragmentary. This type of seizure may be brief and not associated with loss of consciousness.
Category: Fundamentals Clonic seizures consist of rapidly repetitive bilateral jerking of the extremities and facial muscles with loss of consciousness. The postictal phase is usually short. The EEG typically shows generalized high-voltage, spike-wave activity.
Category: Fundamentals Tonic–clonic seizures (grand mal) cause depressed consciousness that can be prolonged (several hours). The patient exhibits bilaterally symmetric clonic jerking of the extremities, increased salivation and frothing at the mouth.
Category: Fundamentals Tonic–clonic seizures (grand mal) are associated with an abrupt loss of consciousness. The patient experiences a sudden, sharp, bilaterally symmetric contraction of muscles and may cry, fall or do both.
Category: Fundamentals A subtype of absence seizure is the atypical absence seizure, in which the alteration of consciousness may not be complete. A child experiencing this type of seizure may continue with some activities.
Category: Fundamentals Absence seizures (petit mal) usually have a sudden onset, are brief (often lasting less than 10 seconds), and interrupt ongoing activities. The patient exhibits a blank stare and is usually unresponsive when spoken to.
Category: Fundamentals Generalized seizures involve both hemispheres of the brain from the onset and they result in early loss of consciousness. Generalized seizures may involve only loss of consciousness (similar to absence seizures).
Category: Fundamentals Complex partial seizures (psychomotor) are associated with impaired consciousness and with some form of automatic behavior. This type of seizure can evolve from a simple partial seizure and can generate a tonic-clonic seizure.
Category: Fundamentals Simple partial (focal) seizures typically result in no alteration of consciousness, and the first clinical and electroencephalogram (EEG) change indicates an initial activation of nerve cells in a limited part of one cerebral hemisphere.
Category: Fundamentals A large group of nerve cells (neurons) must fire abnormally and together to produce an actual seizure. This firing occurs within certain highly organized areas of the brain that tend to support seizure activity. This is known as an epileptic focus.
Category: Fundamentals Predisposing factors that may cause epilepsy more often are sleep deprivation, hyperventilation, fever from an underlying illness, hormonal changes occurring during menses and drug or alcohol ingestion.
Category: Fundamentals Some cases of epilepsy are hereditary or congenital (present at birth), and some are acquired (e.g., serious head injury, a central nervous system [CNS] infection, stroke, or dementia). However, not all people with these disorders develop epilepsy.
Category: Fundamentals Seizures can occur at any age, with etiology varying by age. The most common cause of epilepsy is idiopathic. Other causes of epilepsy include vascular abnormalities (11%), congenital malformations (8%) and trauma (5%).
Category: Fundamentals Epilepsy is a complex neurologic disorder best defined as recurrent seizure activity. A single seizure does not constitute epilepsy unless a brain abnormality is identified, which may result in future seizure episodes.