Jesse M. Pines1,2 and Christopher R. Carpenter3 1 US Acute Care Solutions, Canton, OH, USA 2 Department of Emergency Medicine, Drexel University, Philadelphia, PA, USA 3 Department of Emergency Medicine, Washington University School of Medicine, St. Louis, MO, USA There are nearly 1 million emergency department (ED) visits per year for seizures, with a prevalence rate of 346 per 100,000 US adults.1 The prevalence is highest in 18–44 year age group with a rate of 402/100,000. The vast majority of patients less than 65 years are ultimately discharged from the ED (88%), as compared to the 65–84 age group where 50% are discharged, and 40% in the age 85+ group. The total costs of ED visits related to seizures are estimated at more than $1.15 billion U.S. dollars. The time‐to‐diagnosis of ED seizure is a source of healthcare disparities.2 The initial impression of seizure changes in up to 25% of ED cases within a short period of time with additional information.3 Patients with known seizure disorder should be evaluated distinctly from first‐episode seizure patients presenting to the ED. This chapter will focus on the diagnostic approach to the first‐episode seizure patients. One‐fifth of first‐episode seizure patients are not recognized during their first ED evaluation.4 In particular, migraine headaches and syncope are frequently misdiagnosed as seizure, and sometimes stroke.5 After a first seizure, up to 40–50% of patients will have a recurrence within 2 years.6, This makes it vitally important to ensure that patients who have seizures have clear follow‐up instructions and are educated about the potential for seizure recurrence. The top three etiologies of seizures in ED patients older than 5 years are toxins (19%), head injury (8%), and epilepsy (7%).7 Toxins include ethanol, but only 22% of seizures attributed to alcohol abuse can be explained by withdrawal.8 Therefore, the diagnosis of an alcohol withdrawal seizure should be one of exclusion. Other toxins associated with seizures include cocaine, lidocaine, meperidine, bupropion, carbon monoxide, tramadol, fentanyl, synthetic cannabinoids, organophosphates, and nerve agents.9–11 Unrecognized dysrhythmia can mimic seizures.12,13 Less common diagnoses like cerebral vein thrombosis can also present with seizures.14 Status epilepticus is defined as seizures persisting for over 30 minutes or multiple seizures without a return to normal consciousness in between. In the ED, status epilepticus represents 7% of seizures.15 Mortality for status epilepticus is 3% in children and increases to 38% in older adults.16 One‐quarter of status epilepticus cases are nonconvulsive, which can be a challenging diagnosis, as the patient may present with altered mental statuses such as lethargy or coma.17 Additionally, when seizures are not witnessed by bystanders, emergency physicians must differentiate syncope from seizure. Elevated serum creatine kinase measured 4 hours after loss of consciousness can distinguish syncope from tonic‐clonic seizure.18,19 In children, febrile seizures represent one‐third of seizures presenting to the ED.8 In order to establish the diagnosis of simple febrile seizure, all criteria in Table 49.1 must be met.20 Complex febrile seizures are less well defined and represent a heterogeneous mixture of etiologies. Children with a simple febrile seizure are not at increased risk to develop adult epilepsy compared with those who never had a febrile seizure. However, the risk of recurrent febrile seizure is high, ranging from 12% to 50% depending upon whether the seizure occurred in an infant or toddler. This is a key message that should be explained to parents when discharging a child with a febrile seizure. Table 49.1 Essential criteria to define simple febrile seizure Source: Data from [20]. Pregnant women without preexisting epilepsy can develop a gestational seizure disorder called eclampsia. Preeclampsia usually precedes the development of seizures with hypertension, edema, and +/− proteinuria beginning after the 20th week of pregnancy.21 One‐quarter of eclampsia seizures occur before labor, one‐half during labor, and the rest occur up to 10 days postpartum.22,23 Maternal risk factors for preeclampsia include a family history of preeclampsia, multiple gestations, renal disease, diabetes preceding the pregnancy, nulliparity, and extremes of age.24 Psychogenic seizures, formerly referred to as pseudoseizures, are a diagnosis of exclusion in the ED with a general population prevalence of 0.002–0.33%.25 Psychogenic seizures are sometimes difficult to distinguish from other seizures and are a source of significant healthcare expense.26,27 Psychogenic seizures can also stigmatize patients.28 About one in three patients receive an antiepileptic medication for psychogenic seizures which are not effective in preventing them.29 In addition, the mean delay between seizure onset and psychogenic seizure diagnosis is 7 years.30 Among patients referred to definitive epilepsy diagnostic centers, 30% are ultimately diagnosed with psychogenic seizures.31 To further complicate the issue, epilepsy can coexist with psychogenic seizures in 5–40% of cases.32 Psychogenic seizures may be distinguished from neurogenic seizures by duration (often >90 seconds), presence of corneal reflex, prevention of hand falling on the face, being awake or conversant during the attack, and the absence of a postictal phase or event‐related amnesia.33,34 What diagnostic tests should be performed in well‐appearing children following a febrile seizure? In well‐appearing children with first complex seizure associated with fever, the incidence of significant intracranial pathology is rare (0%, CI 0–4%) and central nervous system (CNS) imaging can often be safely deferred. However, this has several important exclusions including those with prior neurosurgery, significant neurological disorder, or chronic medical illness.35–37 Similarly, studies have not demonstrated any role in routinely evaluating electrolytes or glucose in first‐episode febrile or afebrile pediatric seizure patients.14,38–40 However, laboratory testing is indicated in the ill‐appearing child with vomiting, diarrhea, dehydration, or failure to return to his or her baseline mental status. Which diagnostic tests should be performed in well‐appearing adults presenting to the ED following a first‐episode unprovoked seizure? The American College of Emergency Physicians has provided two Clinical Policies upon which to base diagnostic decision making.41,42 Some of these recommendations are summarized in Figure 49.1. No Level A recommendations were published. The 2004 American College of Emergency Physicians (ACEP) Clinical Policy provides Level B evidence for the following ED diagnostic studies following a first‐episode unproved seizure.
Chapter 49
First‐Episode Seizure
Background
Age 6 months–5 years
Tonic‐clonic seizure
Resolution of convulsions within 15 minutes
Normal mental status after convulsion
Documentation of fever >38.0 °C
Only one seizure in 24‐hour period
Absence of preceding neurological abnormality
Clinical question
Clinical question
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