Epilepsy

Key Features

Essentials of Diagnosis

• Recurrent unprovoked seizures

• Single seizure with an electroencephalogram (EEG) or risk factors suggesting high risk of recurrent events

• Often, interictal EEG changes

General Considerations

• Defined as two seizures that are separated by at least 24 hours, a single seizure associated with a > 60% risk of recurrence or the diagnosis of an epilepsy syndrome

• During childhood, the incidence is highest in the newborn period

• Prevalence flattens out after age 10–15 years

• The chance of having a second seizure after an initial unprovoked episode in a child is about 50%

• Risk of recurrence after a second unprovoked seizure is 85%

• With appropriate medication, seizure remission is achieved in 65–70% of children

Classification

• Focal seizures

  • Previously called partial (with suspected seizure onset that can be localized to one part of the brain)

  • New nomenclature is based on the presentation of the seizure rather than based on the loss of awareness; terms that will allow for better description include

    • Without impairment of consciousness

    • With motor involvement

    • Hypomotor seizure

• Generalized seizures (likely involving the whole brain or a network of the brain) can be categorized into 7 groups

  • Tonic-clonic

  • Absence (typical, atypical, and with special features)

  • Myoclonic

  • Myoclonic atonic

  • Tonic

  • Clonic

  • Atonic seizures

• Epilepsy syndromes

  • Defined by the nature of the seizures typically present, age of onset, EEG findings, and other clinical factors

  • Recommended terms

    • Genetic, to indicate a known or presumed genetic etiology

    • Structural/metabolic, to indicate a known structural or metabolic etiology to an epilepsy syndrome (an example would be tuberous sclerosis or underlying stroke)

    • Unknown, for those patients for whom a cause has not yet been identified.

Clinical Findings

• Obtaining a detailed history is crucial

• Patient may describe a feeling of fear, numbness or tingling in the fingers, or bright lights in one visual field

• Specific symptoms may help define the location of seizure onset (eg, déjà vu suggests temporal lobe onset)

• Postictal states can be helpful in diagnosis

  • After many focal seizures and most generalized convulsive seizures, postictal sleep typically occurs

  • Postictal changes are not seen after generalized absence seizures

  • Motor activity without impaired awareness supports the diagnosis of focal seizures as do impaired awareness and automatisms previously defined as a "complex partial seizure"

• In generalized seizures, acute loss of consciousness, usually with generalized motor activity, usually seen; tonic posturing, tonic-clonic activity, or myoclonus (spasms) may occur

• In generalized absence seizures, behavioral arrest may be associated with automatisms such as blinking, chewing, or hand movements, making it difficult to differentiate between absence seizures and focal seizures

Diagnosis

• Every child with new-onset unprovoked seizures should be evaluated with an EEG and MRI

• Metabolic abnormalities are seldom found in a healthy child with seizures

• Routine laboratory tests rarely yield clinically significant information, unless there ...