Seizure and Epilepsy Diagnosis and Management

Introduction to Seizures and Epilepsy

• The American College of Radiology defines a seizure as a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain, while epilepsy is defined as having at least two unprovoked seizures occurring more than 24 hours apart, one unprovoked seizure with a high probability of recurrence, or diagnosis of an epilepsy syndrome 1, 2
• Approximately 10% of the population will experience at least one seizure during their lifetime, according to the Journal of the American College of Radiology 3
• The International League Against Epilepsy (ILAE) defines epilepsy as at least two unprovoked seizures occurring more than 24 hours apart, one unprovoked seizure and a probability of further seizures similar to the general recurrence risk after two unprovoked seizures, or diagnosis of an epilepsy syndrome 1, 2, 3

Classification and Diagnosis

• The ILAE classification of seizures was last revised in 2017, and seizures are classified as focal onset, generalized onset, or unknown onset 1
• Focal onset seizures arise within networks of a single cerebral hemisphere and may remain localized or become more widely distributed 1, 3
• Generalized onset seizures rapidly affect both hemispheres and both sides of the body, and can be further subdivided into tonic-clonic, other motor, or nonmotor (absence) 1, 4
• Correct identification of seizure type and epilepsy syndrome is crucial for etiologic diagnosis, appropriate treatment selection, and accurate prognostication 1, 3
• Neuroimaging plays a critical role in identifying structural causes, with CT useful in emergent situations and MRI more sensitive for detecting subtle abnormalities 3, 4

Epidemiology and Impact

• Active epilepsy affects approximately 1.2% of the US population (3.4 million people) and 50 million people worldwide, according to the Journal of the American College of Radiology 1
• Epilepsy has significant impact on mortality, morbidity, and quality of life, affecting approximately 65 million people worldwide, although the exact number is not specified in the provided citations

Genetic Factors

• Genetic factors can influence both seizures and epilepsy, with certain genetic syndromes having high rates of both epilepsy and other neurological conditions, as noted in Nature Reviews Neurology 5

Diagnostic Considerations for Seizure and Epilepsy

Introduction to Seizure and Epilepsy Diagnosis

• When uncertain about epilepsy diagnosis, it is better to postpone the diagnosis than to falsely diagnose it, as this has significant treatment and psychosocial implications, according to the European Society of Cardiology 6, 7

Epilepsy Diagnosis and Classification

Epilepsy Type Classification

• The International League Against Epilepsy (ILAE) classifies epilepsy into types, including focal epilepsy, generalized epilepsy, combined focal and generalized epilepsy, and unknown epilepsy, as reported in the European Journal of Nuclear Medicine and Molecular Imaging 8

Etiologic Classification

• The ILAE categorizes the underlying etiology of epilepsy into structural, genetic, infectious, metabolic, immune, and unknown categories, with multiple categories potentially coexisting, as noted in the European Journal of Nuclear Medicine and Molecular Imaging 8
• The etiologic classification includes structural causes such as hippocampal sclerosis, tumor, focal cortical dysplasia, and hemorrhage, as well as genetic, infectious, metabolic, and immune causes, according to the European Journal of Nuclear Medicine and Molecular Imaging 8

Epileptic Seizure Definition and Neonatal Incidence

Definition of Epileptic Seizure

• An epileptic seizure is defined as a transient occurrence of signs and/or symptoms caused by excessive, abnormal, or synchronous neuronal activity in the brain. 9

Epidemiology of Neonatal Seizures

• Neonatal seizures (occurring within the first 0–29 days of life) have an incidence of approximately 3 per 1,000 live births, rising to 57–132 per 1,000 among preterm infants; about 95 % have an identifiable cause, most commonly hypoxic‑ischemic encephalopathy (46–65 %), followed by intracranial hemorrhage and perinatal stroke (10–12 %). 9

Diagnosis and Management of Formication as an Ictal Aura

Essential First‑Line Testing

• Perform video‑EEG monitoring at least 24 hours after focal aware seizures and at least 48 hours after focal impaired‑awareness or focal‑to‑bilateral tonic‑clonic seizures to improve detection of interictal epileptiform activity. 10
• Obtain a high‑resolution epilepsy‑protocol MRI (3 T preferred) to identify structural lesions such as focal cortical dysplasia, hippocampal sclerosis, or subtle neoplasms that commonly underlie focal epilepsy. 10

Advanced Imaging When MRI Is Inconclusive

Both nuclear‑medicine studies are recommended when MRI does not reveal a lesion but clinical suspicion for focal epilepsy remains high. 10

Differentiating Epileptic Aura from Syncope

• Post‑event confusion or prolonged sleepiness (lasting more than a few minutes after regaining consciousness) strongly favors epilepsy over syncope. 11
• Timing of abnormal movements: In epilepsy, motor phenomena (e.g., tonic or clonic activity) can precede the fall; in syncope, myoclonic jerks occur only after collapse due to cerebral hypoperfusion. 11

Surgical Prognostic Indicators

• Concordance between SISCOM hyperperfusion maps and the planned resection site is associated with a three‑fold increase in the odds of postoperative seizure freedom. 10