What is the approach to identifying and managing clinical manifestations of seizures, such as epilepsy?

Clinical Manifestations of Seizures

Seizures present with diverse clinical manifestations that require systematic identification through specific historical features and physical findings, followed by targeted laboratory and imaging evaluation to identify life-threatening causes and guide management decisions.

Key Clinical Features to Identify

Seizure Characteristics

• Tonic-clonic movements that are prolonged and begin simultaneously with loss of consciousness strongly suggest true seizure activity 1
• Approximately 28-48% of suspected first seizures have alternative diagnoses including syncope, nonepileptic seizures, panic attacks, or other conditions, making detailed characterization essential 1
• Seizures can be classified as provoked (occurring within 7 days of acute insult such as electrolyte abnormalities, withdrawal, toxic ingestions, encephalitis, or CNS mass lesions) or unprovoked (occurring without acute precipitating factors) 1
• Remote symptomatic seizures result from CNS or systemic insults that occurred more than 7 days in the past, such as stroke or traumatic brain injury 1

Critical Historical Elements

• History of alcohol use/dependence or withdrawal is a significant risk factor, though alcohol withdrawal seizures should be a diagnosis of exclusion, especially in first-time presentations 1
• Fever-related seizures or febrile convulsions should be considered as potential causes 1
• History of conditions that increase seizure risk, including hypocalcemia or other electrolyte abnormalities, particularly in patients with 22q11.2 deletion syndrome where lifetime epilepsy prevalence is 5-7% 1
• Prior neuroimaging showing structural abnormalities such as mass lesions, stroke, or cortical malformations helps identify potential causes 1

Immediate Laboratory Evaluation

Essential Tests for All Patients

• Determine serum glucose and sodium levels in all patients with new-onset seizures, as these are the most frequent abnormalities identified and the only laboratory tests that consistently alter acute management 2, 1
• Hypoglycemia and hyponatremia are the most common metabolic abnormalities, usually predicted by history and physical examination, but occasional unsuspected cases occur 2
• Obtain a pregnancy test if the patient has reached menarche or is of childbearing age, as this affects testing, disposition, and antiepileptic drug therapy decisions 2, 1

Selective Laboratory Testing

• In patients with known cancer or renal failure, obtain calcium and magnesium levels 1
• Consider toxicology screening across the entire pediatric age range if there is any question of drug exposure or substance abuse 2, 1
• Additional laboratory tests such as CBC and comprehensive metabolic panel should be obtained only when suggested by specific clinical findings such as vomiting, diarrhea, dehydration, or failure to return to baseline alertness 2, 1

Neuroimaging Strategy

Emergent CT Head Without Contrast Indications

• Perform emergent head CT without contrast for patients with any of the following high-risk features: 1

  • Age >40 years
  • History of malignancy or immunocompromised state
  • Fever or persistent headache
  • Focal seizure onset before generalization
  • Recent head trauma
  • Persistent altered mental status
  • New focal neurological deficits
  • Patients on anticoagulation
  • Partial-onset seizures

• Approximately 41% of first-time seizure patients have abnormal CT findings, though 22% of patients with normal neurologic examinations still have abnormal imaging 1

Non-Emergent MRI Indications

• MRI is the preferred imaging modality for non-emergent evaluation of new-onset seizures as it is more sensitive than CT for detecting epileptogenic lesions 1
• For low-risk patients (young, returned to baseline, normal neurologic exam, reliable follow-up), deferred outpatient MRI is acceptable 1
• For children with focal seizures, MRI with dedicated epilepsy protocol is indicated, as nearly 50% will have positive findings 1

Lumbar Puncture Indications

• Perform lumbar puncture (after head CT) primarily when there is concern for meningitis or encephalitis, particularly in patients with fever and meningeal signs 2, 1
• Lumbar puncture is recommended for immunocompromised patients, either in the ED or after admission 2, 1
• Routine lumbar puncture is not indicated for uncomplicated first-time seizures in alert, oriented, afebrile, non-immunocompromised patients 2
• In one retrospective pediatric series of 503 cases of meningitis, there was no case of occult bacterial meningitis manifesting solely as a simple seizure 2

Electroencephalography (EEG)

• EEG is recommended as part of the neurodiagnostic evaluation of patients with apparent first unprovoked seizure 2, 1
• Abnormal EEG findings predict increased risk of seizure recurrence 1
• EEG findings are crucial for diagnosis, with generalized seizures typically showing bilateral, synchronous discharges 3

Seizure Recurrence Risk Assessment

Timing of Recurrence

• The mean time to first seizure recurrence is 121 minutes (median 90 minutes), with more than 85% of early recurrences occurring within 6 hours of ED presentation 1
• The overall 24-hour recurrence rate is 19%, decreasing to 9% when alcohol-related events and focal CT lesions are excluded 1

Risk Stratification

• Nonalcoholic patients with new-onset seizures have the lowest recurrence rate (9.4%), while alcoholic patients with seizure history have the highest (25.2%) 1
• The risk of recurrence at 1 year ranges from 14-36%, with higher risk in those with abnormal neurological examination, abnormal EEG, remote symptomatic seizures, or Todd's paralysis 1
• High risk for recurrence is present when there is a history of brain insult, an EEG demonstrates epileptiform abnormalities, and MRI demonstrates a structural lesion 4

Disposition Decisions

• Emergency physicians need not admit patients with a first unprovoked seizure who have returned to their clinical baseline in the ED 1
• Consider admission if any of the following are present: persistent abnormal neurologic examination results, abnormal investigation results requiring inpatient management, or patient has not returned to baseline 1

Status Epilepticus Recognition and Management

Clinical Recognition

• Status epilepticus is defined as at least 30 minutes of persistent seizures or a series of recurrent seizures without complete return to full consciousness between seizures, though some propose shortening the time criteria to 5 minutes 2
• Generalized tonic-clonic status epilepticus occurs in 50,000 to 150,000 patients per year in the United States with mortality rates ranging from 5% to 22%, and as high as 65% in those refractory to first-line therapies 2
• Between 5% to 17% of patients will have a seizure while in the ED, and up to 7% will have status epilepticus 2

Immediate Treatment

• For status epilepticus, the usual recommended dose of lorazepam is 4 mg given slowly (2 mg/min) for patients 18 years and older 5
• If seizures cease, no additional lorazepam is required; if seizures continue or recur after a 10-15 minute observation period, an additional 4 mg intravenous dose may be slowly administered 5
• Equipment necessary to maintain a patent airway should be immediately available prior to intravenous administration of lorazepam 5
• Benzodiazepines are first-line therapy for status epilepticus, followed by either phenytoin/fosphenytoin, valproate, or levetiracetam 1

Common Pitfalls to Avoid

• Failing to identify metabolic abnormalities such as hypoglycemia or hyponatremia that may be causing the seizure 1
• Missing structural lesions by not performing appropriate neuroimaging in high-risk patients 1
• Assuming all seizure-like events are true epileptic seizures without considering alternative diagnoses like syncope or nonepileptic psychogenic seizures 1, 6
• Labeling seizures as alcohol withdrawal without excluding other symptomatic causes, especially in first-time presentations 1
• Failing to recognize that status epilepticus is a potentially life-threatening condition requiring immediate intervention beyond just anticonvulsant administration 5

Long-Term Complications and Prognosis

• Status epilepticus is associated with long-term complications including epilepsy (20-40%), encephalopathy (6-15%), and focal neurologic deficits (9-11%) 7
• Mortality rates are 15-20% in adults and 3-15% in children with status epilepticus 7
• Approximately 10% of the population will have one or more seizures during their lifetime, while epilepsy affects 1-3% of the population 4
• More than 15% of patients with epilepsy have at least one episode of status epilepticus, and low antiepileptic drug levels are a potentially modifiable risk factor 7