What is the approach to managing different types of seizures?

Seizure Types and Clinical Approach

Seizure Classification

Seizures are fundamentally classified as either provoked (acute symptomatic) or unprovoked, with provoked seizures occurring within 7 days of an acute insult and unprovoked seizures occurring without identifiable precipitating factors. 1

Major Seizure Types

• Focal seizures (previously called partial seizures) originate from one hemisphere and may present with complex symptomatology including psychomotor features or temporal lobe involvement 2
• Generalized tonic-clonic seizures (grand mal) involve bilateral hemispheric activation from onset 2
• Absence seizures (petit mal) present with brief behavioral arrest and loss of consciousness, often without convulsive activity 2
• Status epilepticus represents continuous seizure activity or recurrent seizures without recovery of consciousness between episodes, constituting a life-threatening emergency 3, 4

Initial Evaluation Approach

History and Physical Examination

The history and physical examination predict most metabolic abnormalities except occasional cases of hypoglycemia and subdural hematomas, making them critical first steps. 1

• Focal neurologic findings have 97% correlation with symptomatic (structural) seizures and mandate urgent neuroimaging 1
• Fever in seizure patients warrants strong consideration of CNS infection including meningitis or encephalitis 1
• Altered mental status persisting after seizure suggests serious structural lesion, metabolic derangement, or ongoing non-convulsive status epilepticus 3

Laboratory Testing for New-Onset Seizures

For otherwise healthy adults with new-onset seizures who have returned to baseline, routine laboratory testing has low yield, with only 8% showing correctable abnormalities. 3

• Immediate glucose testing is essential as hypoglycemia is one of the few metabolic causes not reliably predicted by history 3
• Electrolyte panel should be obtained to identify hyponatremia, hypocalcemia, and hypomagnesemia, particularly in patients with renal failure or chronic alcoholism 1
• Additional testing in specific populations: HIV testing in immunocompromised patients (who have higher rates of CNS toxoplasmosis, lymphoma, and cryptococcal meningitis), pregnancy testing in women of childbearing age 3, 1

Neuroimaging Strategy

When feasible, perform neuroimaging of the brain in the ED on patients with first-time seizures, though deferred outpatient imaging may be used when reliable follow-up is available. 3

Emergent CT Indications (Perform Immediately in ED):

• New focal neurologic deficits 3
• Persistent altered mental status 3
• Fever suggesting CNS infection 3
• Recent head trauma 3
• History of malignancy 3
• Anticoagulation therapy 3
• Known or suspected HIV infection 3
• Age >40 years 3
• Focal seizure onset 3

MRI Superiority:

• MRI is superior to CT for identifying structural abnormalities, detecting lesions in 55% of children versus 18% with CT, and identifying cortical malformations such as polymicrogyria, periventricular nodular heterotopia, or cortical dysplasia 3
• For focal seizures, MRI with epilepsy protocol is essential as routine protocols may miss epileptogenic lesions 3

Acute Management by Seizure Type

Status Epilepticus

For status epilepticus, the usual recommended dose is lorazepam 4 mg IV given slowly (2 mg/min) for patients ≥18 years, with a second 4 mg dose if seizures continue after 10-15 minutes. 4

• Lorazepam is significantly superior to phenytoin alone (65% vs 44% effectiveness) for overt status epilepticus 3
• Airway management is critical: equipment for maintaining patent airway and supporting ventilation must be immediately available as respiratory depression is the most important risk 4
• After benzodiazepine administration, load with phenytoin or fosphenytoin to prevent seizure recurrence 3
• Refractory status epilepticus requires IV anesthetics or pharmacological coma induction 5

Focal Seizures

Carbamazepine is indicated for partial seizures with complex symptomatology (psychomotor, temporal lobe), with patients showing greater improvement than those with other seizure types. 2

• Focal seizures require aggressive workup as they have high correlation (97%) with structural lesions 1
• Surgical evaluation should be considered early in medically refractory cases to prevent years of uncontrolled disease 6

Generalized Tonic-Clonic Seizures

• Carbamazepine is effective for generalized tonic-clonic seizures and mixed seizure patterns 2
• Absence seizures do not respond to carbamazepine and require alternative agents 2

Admission and Antiepileptic Drug Initiation

Admission decisions should be based on identifying underlying life-threatening etiologies, risk of seizure recurrence, and ability to ensure safe follow-up. 3

High-Risk Features Requiring Admission:

• Abnormal CT showing acute stroke, tumor, or intracranial hemorrhage 3
• Persistent altered mental status 3
• Recurrent seizures in ED (occurs in 15% of patients) 3
• Metabolic abnormalities requiring correction 3
• Inability to ensure reliable outpatient follow-up 3

Antiepileptic Drug Initiation:

• IV phenytoin or fosphenytoin loading achieves therapeutic levels (≥10 mg/L) within minutes after infusion completion 3
• Oral phenytoin loading (single or divided doses) achieves therapeutic levels in 3-8 hours 3
• Maintenance dosing without loading requires 3-7 days to reach therapeutic levels 3

Common Etiologies by Population

Adults:

• Most common causes: antiepileptic drug noncompliance (in known epileptics), alcohol-related seizures, stroke, tumors, and idiopathic 3
• Alcohol-related seizures: 58% of patients have abnormal CT, with 6% showing clinically significant lesions requiring management changes 3

Neonates:

• Hypoxic-ischemic injury is the most common cause (46-65%), with 90% occurring within 2 days of birth 1
• Intracranial hemorrhage and perinatal stroke account for 10-12% 1
• An underlying cause is identified in 95% of neonatal seizures 1

HIV/Immunocompromised:

• CNS toxoplasmosis, lymphoma, cryptococcal meningitis, and HIV encephalopathy are primary considerations 1
• Both CT and lumbar puncture are recommended, as 2 afebrile HIV patients without meningeal signs had positive LP results 3

Critical Pitfalls to Avoid

• Never assume alcohol withdrawal without eliminating symptomatic causes, as 6% of presumed alcohol withdrawal seizures have clinically significant intracranial lesions 3
• Do not use phenytoin for seizures secondary to alcohol withdrawal, theophylline toxicity, or isoniazid toxicity as it is ineffective 7
• Consider non-convulsive status epilepticus in any patient with unexplained confusion or coma and obtain EEG at earliest opportunity 7
• Recognize that most medically ill patients with secondary seizures do not have epilepsy and do not require long-term anticonvulsant therapy unless recurrent seizures occur with uncorrectable predisposing factors 7
• Complete seizure control should be the goal as uncontrolled seizures cause brain injury, neuronal death, and 4-7 times higher mortality rates 8