Seizures are the clinical manifestations of abnormal, increased, synchronized electrical activity in the brain. An estimated 10% of the population experience at least one seizure in their lifetime, and of those, 3% develop epilepsy, which is a condition of recurrent unprovoked seizures.
Seizures may occur as a result of an acute underlying condition or insult—termed a provoked
or acute symptomatic
seizure. A seizure that occurs in the absence of such a condition is termed unprovoked
. One of the goals in emergency practice is to identify those causative conditions that may lead to further harm and address them if possible (Table 17.1
). Seizures can also be due to sequelae of a prior intracranial insult such as stroke, trauma, or anoxia, in which case it is referred to as a remote symptomatic seizure
is often used to refer to the period during which a seizure occurs. Currently used classification systems are summarized in Table 17.2
and Figure 17.1
Seizures can be either convulsive
; in the latter case, motor activity is not a key component of the presentation. Seizures may also be classified as focal
. Focal or partial seizures occur when the abnormal electrical activity is limited to one area of the brain. These may manifest as motor, sensory, autonomic, or behavioral depending on their location. Signs and symptoms can be nonspecific, ranging from jerking of one limb or muscle group, to a strange taste or smell, or a sense of déjà vu or hyper spirituality. In some cases, focal electrical activity can spread to other areas and to the contralateral hemisphere. The symptoms progress in kind until the whole brain and whole body are involved, resulting in a generalized seizure.
Generalized seizures involve both hemispheres of the brain and may also be convulsive (commonly tonic-clonic
) or nonconvulsive. Some seizures may be preceded by an aura
, which is itself actually a focal seizure that may help identify the location of an epileptic focus, for example déjà vu points to the temporal lobe. Status epilepticus
(SE) is a subset of generalized seizures characterized by a single prolonged ictal period or multiple recurrent seizures without return to baseline. This is a true neurologic emergency that is associated with high rates of neurologic injury as well as nonneurologic morbidity and mortality. SE may be convulsive status epilepticus (CSE) or nonconvulsive status epilepticus (NCSE) at the outset. CSE that is undertreated or untreated may progress to NCSE. Historically, SE was defined as a seizure lasting longer than 30 minutes, but current guidelines recommend beginning treatment after only 5 minutes of convulsive activity.2
TABLE 17.1 Differential Diagnosis of Provoked Seizures
a The most common metabolic cause of seizures.
b A rare cause of seizures except in infants younger than 6 months old.
c Rarely an isolated cause of seizures; possibly facilitates seizures, especially in malnourished patients, for example, alcoholics.
d Consider the following in overdose.
TABLE 17.2 Seizure Classification
Simple partial (without alteration of consciousness)
Primary generalized nonconvulsive
Primary generalized convulsive
a Subtle convulsive status epilepticus is sometimes classified as a type of nonconvulsive status epilepticus; however, it is the end stage of a convulsive event and has a very high mortality.
Figure 17.1: International League Against Epilepsy (ILAE) epilepsy classification. EEG, electroencephalogram. Based on Fisher RS, Cross JH, D’Souza CD, et al. Epilepsia2017 instruction manual for 2017 ILEA seizure definitions.pdf. Epilepsia. 2017;58(4):531-542.
TABLE 17.3 Differential Diagnosis of Patient of Altered Mental Status After a Seizure
Nonconvulsive status epilepticus or subtle convulsive status
CNS vascular event
CNS, central nervous system.
Most seizures last under 5 minutes, although they may be followed by a period of confusion or altered mental status termed the postictal period
. This is a normal, benign condition that rarely lasts > 1 hour. A prolonged episode of altered mental status following a seizure should prompt investigation of other causes (Table 17.3
The key to seizure diagnosis and management in the emergency department (ED) is gathering as much supporting history as possible and performing a careful neurologic examination to uncover evidence that a seizure took place or is still ongoing. The diagnosis of seizures may not be straightforward; 17% of patients referred to specialty epilepsy centers for “refractory seizures” do not actually have a seizure disorder and may be exposed to unnecessary medications or driving restrictions.3
More recently, 10% of patients enrolled in a large multicenter study of SE were determined to have been having psychogenic convulsions.4
Compounding diagnostic error is the failure to consider and or recognize nonconvulsive seizures in patients with altered behavior or are in coma: In one report, 12% of comatose patients in intensive care units (ICUs) were found to be in NCSE.5
Seizures are a common reason patients activate emergency medical services (EMS). Although most patients evaluated by prehospital providers will have stopped seizing by the time of first contact, a small but important minority will have persistent convulsions and should generally be presumed to be in SE. Multiple trials have demonstrated that treatment of seizures by prehospital providers is safe, efficacious, and results in improved patient outcome.6
EMS protocols for managing prehospital SE vary by region, but must take into account the feasibility of drug storage and challenges to parenteral administration in the prehospital environment. Management begins with a blood glucose determination, whereas intramuscular (IM) midazolam or intravenous (IV) lorazepam are recommended first-line abortive therapies. Rectal diazepam is not first line because absorption and onset are variable. Other commonly performed interventions include provision of supplemental oxygen and continuous monitoring of SpO2
and end-tidal CO2
For patients who have had a witnessed seizure but are not actively seizing, no specific therapy is indicated. Routine supportive care should be provided, and the patient should be placed in a position of comfort to facilitate maintenance of a patent airway and to prevent hypoxia. Routine IV placement may be considered, but is not mandatory. Precautions should be taken to prevent patient and provider injury in the case of recurrent seizure.