| Impaired
Awareness
Motor Onset
automatisms
atonic
clonic
epileptic spasms
hyperkinetic
myoclonic
tonic
Nonmotor Onset
autonomic
behavior arrest
cognitive
emotional
sensory
Focal to bilateral
tonic‐clonic
Generalized Onset Motor
tonic‐clonic
clonic
myoclonic
myoclonic‐tonic‐clonic
myoclonic‐atonic
atonic
epileptic spasms
Nonmotor (absence)
typical
atypical
myoclonic
eyelid myoclonia
Unknown Onset Motor
tonic‐clonic
epileptic spasms
Nonmotor
behavior arrest
A fundamental distinction is whether the seizure is of focal onset or generalized onset. This distinction may be important clinically because focal onset seizures may imply focal or structural CNS abnormalities and because different medications are effective in different seizure types. In focal onset seizures, clinical information indicates that seizure onset is limited to one part of the brain. Focal seizures may be further divided into seizures with awareness preserved and seizures with impaired awareness. In aware focal onset seizures, the patient remains at normal consciousness. Focal seizures with sensory symptoms include some patients with episodic paresthesias. Special sensory symptoms with focal seizures may have gustatory, olfactory, or auditory symptoms. The recent classification system uses the term seizures with impaired awareness in place of complex partial seizures. Symptoms of these patients often include altered mental status with confusion and simple repetitive motor movements such as lip smacking or picking at clothes. Sometimes, prolonged confusional states occur from seizures with impaired awareness, one of the types of nonconvulsive status epilepticus [18].
Generalized onset seizures imply that the cerebral cortex is bilaterally involved at seizure onset. This often requires EEG evaluation for definitive diagnosis. However, some seizure types are typical enough in appearance that they can be classified by observation alone. Focal‐onset seizures with secondary generalization are the most common type of generalized seizure in adults. An example of a focal onset seizure with secondary generalization would be a patient with onset of finger twitching, progression of movements to the arm and face, and then a subsequent generalized convulsive seizure. Unfortunately, often this secondary generalization occurs too rapidly to be appreciated by witnesses or in the field.
A few words concerning terminology are in order. Convulsion refers to the motor movements associated with a seizure. Tonic refers to the stiffening of the extremities seen in convulsions. Clonic is the rhythmic, synchronized movements of the extremities. Some patients experience an aura, which is the initial subjective perception of a seizure. Grand mal is generally used in a manner to be synonymous with a generalized convulsion. Petit mal, however, is so frequently misused by patients and physicians that perhaps that term is best not used. Correctly used, it is synonymous with absence seizures, a generalized onset seizure that has a characteristic EEG three‐cycle‐per‐second pattern. In common usage, however, petit mal is corrupted by association with the word petite, meaning “small,” so that fragments of seizures or partial seizures are incorrectly labeled petit mal seizures.
Symptomatic seizures
A basic point in assessment and management is whether a seizure is secondary to some medical condition, such as electrolyte abnormalities, toxins, hypoxia, CNS infections, systemic infections, or trauma. EMS plays a key role in gathering historical information to identify likely seizure causes. A few causes of symptomatic seizures warrant particular comment.
Alcohol withdrawal seizure is a type of symptomatic seizure that usually occurs within 48 hours of cessation of drinking [19]. Usually alcohol withdrawal seizures are single and brief, but up to 30% of patients have recurrent seizures in the ED [20, 21]. Studies of patients with status epilepticus show that a significant proportion are alcohol‐related [22].
Many different toxins may cause seizures [23, 24]. Sympathomimetics, including cocaine, are perhaps the most frequently encountered. Other toxins that may cause seizures include antidepressants, antihistamines, salicylates, and anticholinergics. Isoniazid, used to treat tuberculosis, deserves specific mention because the mechanism of action of the drug requires a specific antidote: pyridoxine (vitamin B6) [25].
Seizures in association with advanced pregnancy or in the postpartum patient may represent eclampsia. Hypertension is present. Treatment involves magnesium sulfate and possibly benzodiazepines.
Febrile seizures
Febrile seizures are one of the most common seizure types encountered in emergency practice, in both the field and the ED. Definitions in the literature vary, but a seizure associated with fever in children aged 6 months to 5 years without evidence of intracranial infection or other definite cause of seizure is an accepted definition. The age‐delineated definition acknowledges the sensitivity of the maturing brain to fever [26]. Excluded are fever‐associated seizures in patients who have experienced afebrile seizures in the past. Peak incidence is at 18 months. Other events that may simulate seizures in this age group include rigors, breath‐holding spells, apneic episodes, and anoxic seizures. History is key in sorting out these events.
Many febrile seizures occur early in the course of the underlying illness and may be the presenting symptom of the illness. The magnitude and peak of the fever are likely to be more important in provoking seizures than the rate of increase. Antipyretics have not been shown to be effective in reducing the risk of febrile seizures [26].
Febrile seizures are often divided into simple and complex types. A simple febrile seizure is a generalized tonic‐clonic convulsion without focal signs lasting less than 10 minutes, resolving spontaneously, and not recurring within 24 hours. Complex febrile seizures fall outside this definition due to focal signs during the seizures, seizure duration, or recurrence.
By definition, a simple febrile seizure will likely have ceased by arrival of EMS, unless the response interval is very short. Recurrent or prolonged seizures exclude this diagnosis and point to a complex febrile seizure or another cause for the seizure. EMS clinicians should elicit important historical details, including preceding irritability, decreased feeding, or abnormal consciousness that might suggest an underlying CNS infection. Most children experiencing febrile seizures recover within 30 minutes. Postictal alteration of consciousness persisting more than 60 minutes has been suggested as a risk factor for a complicating medical condition [27].
Status epilepticus
Ongoing seizures or status epilepticus may occur in any seizure type and terminology may be confusing (Box 17.3). Generalized convulsive status epilepticus represents a true emergency condition because the ongoing