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EEG Recording Cap

 Image  “An EEG can aid in locating the focus of the epileptic seizure”  by Chris Hope.  License: CC BY-SA 2.0


Overview

The term epilepsy refers to recurrent, unprovoked seizures that can result from a known or an unknown cause.

A patient diagnosed with epilepsy who presents with a seizure is considered an epilepsy emergency.

A seizure is not necessarily motor; it is defined as an episode of neurologic dysfunction caused by abnormal neuronal activity. It can be characterized by a sudden change in senses, perception, or behavior. A convulsion is a seizure occurrence with motor activity.

A seizure may be focal or generalized. A focal seizure occurs in one part of the brain, while a generalized seizure begins in one part of the brain but then spreads to both sides.

Status epilepticus is a state of recurrent/ prolonged seizures without a return to consciousness for more than five minutes. Epilepsy syndrome is a clinical entity of consistent clinical features, such as the age of presentation, EEG pattern, seizure type, and response to antiepileptic medications.

When a patient is having a seizure, the term ictus is used to describe the period of seizing. The term postictal refers to the period that follows the seizure. An overview:

  • Ictal period: Time when a seizure occurs
  • Post-ictal period: Period of altered mental status following a seizure
  • Status epilepticus: Seizure activity > 5 minutes OR recurrent seizure activity without return to baseline mental status
  • Epilepsy: Unprovoked seizure

Pathophysiology of Seizures

Because a seizure is characterized by abnormal neuronal activity, one expects to find abnormalities in the neurotransmitters and their receptors in the brains of patients with epilepsy. It is currently accepted that patients who have seizures have an abnormal balance between excitatory neurotransmitters and inhibitory neurotransmitters.

The main excitatory neurotransmitter in the brain is glutamate. Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the brain. An abnormality in the receptors of these neurotransmitters might result in repeated, abnormal electrical discharges that are responsible for the seizure. The seizure semiology depends on the extent of the abnormal neuroelectrical activity propagation.

The most common causes of a seizure are:

  • Medical noncompliance in a patient with a known history of an epilepsy disorder
  • Stress
  • Lack of sleep
  • Caffeine use

A new-onset seizure disorder may be the first presentation of an epilepsy disorder. Epileptic seizure activity mostly originates from a discrete region of the cortex in the initiation phase that is characterized by two events in an aggregate of neurons, i.e., a high-frequency burst of action potential and hypersynchronization.

Later, the effect then spreads to other brain areas during the propagation phase. This leads to increased levels of NMDA and Calcium ions that exacerbate the situation due to enhanced neurotransmitter release.

Neurotransmitters disturbed Increased sympathetic stimulation Increased autonomic stimulation
Increased excitatory neurotransmitters:

  • Acetylcholine
  • Glutamate
  • Increased temperature
  • Elevated lactic acid
  • Increased heart rate and respiratory rate
  • Urinary and fecal incontinence
  • Tongue biting
  • Possible airway issue

Epidemiology of Epilepsy and Seizures

Up to 200,000 new cases of epilepsy or seizures occur in the United States each year. Half of these cases will be classified as an epilepsy disorder once the seizures recur. In the United States, 50,000 to 150,000 patients will reach status epilepticus, which is an epilepsy emergency, every year. The most important risk factors for epilepsy and new-onset seizure disorder include head trauma, history of stroke, and a family history of epilepsy.

The risk of a recurrent seizure after the first seizure overall is around 40%. A recurrent seizure after a first seizure will most commonly occur in the first six months.

Clinical Presentation of Epilepsy and Seizures in the Emergency Department

When a patient presents to the emergency department with a seizure, it is important to establish whether it is the first seizure or a recurrent one.  If the patient has a known history of an epilepsy disorder, compliance with antiepileptic medications should be checked. When a patient presents with a new-onset seizure disorder in an emergency setting, a medical history, physical examination, and workup should be completed to rule out other causes, such as stroke, brain tumor, intracranial hemorrhage, trauma, hypoxia, vascular abnormality, hypoglycemia, electrolyte disturbances, meningitis, encephalitis, alcohol or medication withdrawal, drug-induced seizures, and malaria.

Early posttraumatic seizures can occur in patients with severe traumatic brain injuries, especially if the patient developed an intracranial hemorrhage. Using prophylactic antiepileptics in patients with severe traumatic brain injuries might have a small role in reducing the risk of early posttraumatic seizures. In this scenario, prophylactic antiepileptics do not affect the risk of late posttraumatic seizures.

Intracranial hemorrhage, whether traumatic or spontaneous, can predispose the patient to an increased risk of seizures. The sizes and locations of such bleeds are key factors in defining the risk of seizures. Large temporal lobe intraparenchymal bleeds are more likely to result in seizures than small deep intraparenchymal bleeds.

Medication history is important in the emergency department setting when dealing with a patient who is presenting with seizures. Tricyclic antidepressants and isoniazid overdose can cause seizures.

The physician should also try to characterize the seizure activity by its duration, manifestation, associated warning signs, such as photophobia, and interictal occurrences, such as tongue biting, eye-rolling, and excessive salivation.

Laboratory Investigations in Patients Presenting with Seizures to the Emergency Department

Laboratory tests have a small role in the diagnostic workup of a patient presenting with seizures. It is important to exclude hypoglycemia/hyperglycemia and electrolyte abnormalities as potential causes of seizures in any patient presenting with a new-onset seizure disorder. Up to 15% of those presenting with a new-onset seizure disorder have abnormal results in their laboratory testing. Women presenting with seizures should receive a pregnancy test to exclude pre-eclampsia and eclampsia, both of which occur in pregnant women.

Patients with new-onset persistent fever, severe headache, altered mental status examination, and new-onset seizures should receive a lumbar puncture to exclude meningoencephalitis.

Imaging Studies in Patients Presenting with Seizures to the Emergency Department

All patients with new-onset seizures or those presenting with status epilepticus to the emergency department should receive a non-contrast computed tomography scan as soon as possible while at the emergency department. The rationale behind this recommendation is to exclude life-threatening, catastrophic causes of seizures, such as intracranial hemorrhage.

Patients presenting with a first-time generalized tonic-clonic seizure who have returned to normal and have no neurological deficits on their examination should receive a computed tomography scan of the head. However, this can be done in an outpatient setting. If computed tomography is available at the emergency department, all patients presenting with seizures should be screened even if they have returned to a normal baseline.

Spike-waves

 Image  “An electroencephalogram of a person with childhood absence epilepsy showing a seizure”  by Der Lang.  License: CC BY-SA 2.0

Patients who have a history of malignant disease or immunocompromise, or who receive anticoagulation therapy, and present with new-onset seizures should receive a computed tomography scan at the emergency department. Those presenting with new-onset seizures and new-onset neurological deficits should also receive a computed tomography scan at the emergency department.

Patients in status epilepticus should also receive a phalography (EEG) study if available at the emergency department. This is important because an EEG can identify whether the problem is focal or generalized and can provide valuable information about the prognosis.

Treatment of Seizures at the Emergency Department

Any patient presenting with status epilepticus should receive early and prompt treatment to halt the status epilepticus. When a patient presents to you with seizures at the emergency department, three important points should be emphasized before treating the patient:

  1. A patient with an altered mental status or in a coma might have non-convulsive seizures. An EEG can confirm this diagnosis.
  2. Aggressive control of the seizure is recommended to avoid permanent neurological damage.
  3. Identifying the etiology of the seizure is essential for proper management after the patient is discharged from the emergency department.

Any patient presenting with a seizure to the emergency department should receive ABCDE care. Temperature assessment and blood glucose levels should be determined in all patients presenting with seizures to the emergency department. Intravenous access is recommended for all patients in the emergency department setting.

Benzodiazepines should be administered intravenously, intramuscularly, or rectally, especially in those with prolonged seizures or status epilepticus. Lorazepam is the benzodiazepine of choice in managing seizures in an emergency setting. Intranasal midazolam or rectal diazepam are also good options for the emergency care of a patient presenting with a seizure.

If benzodiazepines fail to control the seizures in the emergency setting, phenytoin should be administered. Patients who do not respond to benzodiazepines and phenytoin are diagnosed with refractory status epilepticus.

Patients diagnosed with refractory status epilepticus should receive barbiturates or Propofol. The aim is to limit the duration of the seizure below five minutes if possible and below 20 minutes in all patients. Phenobarbital is a reasonable option for patients with refractory status epilepticus.

First-time seizure Known seizure disorder
  • Close outpatient follow up
  • No initiation of antiepileptic treatment recommended
  • Check medication levels
  • Load or administer medications as needed
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