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. 2022 May 12;63(7):1761–1777. doi: 10.1111/epi.17274

TABLE 2.

Consensus regarding seizure types and evolution with time and diagnostic testing

Other seizure types: frequency and age at presentation

Myoclonic seizures
  • Seen in 50–90% of cases (PHYSICIANS: n = 19, 84%; caregivers : n = 7, 71%).
  • Typically begin between 1 and 3 years of age (PHYSICIANS: n = 19, 89%; caregivers : n = 6, 67%), but all physicians and 4/5 caregivers who responded indicated they may be seen in the first year of life.
Absence seizures
  • No consensus on whether these are seen in majority of cases or not (physicians or caregivers).
  • Typically begin between 1 and 5 years of age (PHYSICIANS: n = 19, 89%; CAREGIVERS: n = 5, 80%), but 53% of physicians and 1/3 caregivers who responded indicated they could begin in the first year of life.
Focal impaired awareness seizures
  • Seen in more than half of cases ( physicians : n = 19, 74%; CAREGIVERS: n = 5, 100%).
  • Typically, onset is between 1 and 5 years (PHYSICIANS: n = 14, 86%; caregivers a : n = 4, 75%), but 57% of physicians and 1/3 caregivers indicated they could begin in the first year of life.
Atonic seizures
  • Seen in fewer than half of cases (PHYSICIANS: n = 19, 100%; caregivers a : n = 2, 100%).
  • Typically, onset is between ages 1 and 5 years (PHYSICIANS: n = 14, 93%; caregivers a : n = 1, 100%), but 8% of physicians and 1/3 caregivers indicated they could begin in the first year of life.
Tonic seizures
  • Seen in fewer than half of cases ( physicians : n = 19, 79%); seen in more than half of cases (CAREGIVERS: n = 6, 83%).
  • No consensus for typical age at onset (physicians or caregivers), and only 7% of physicians but 4/4 caregivers indicated they could begin in the first year of life.
Nonconvulsive (obtundation) status epilepticus
  • Seen in 10%–49% of cases (PHYSICIANS: n = 19, 84%; caregivers a , n = 4, 50%).
  • Usually starts in the first decade of life (PHYSICIANS: n = 14, 93%; caregivers a : n = 2, 100%), but only 29% of physicians and 0/2 caregivers indicated this could begin in the first year of life.
Persistence of seizure types into adulthood
  • Myoclonic seizures:
    1. Persist in fewer than half of cases into adulthood (PHYSICIANS: n = 14, 86%; caregivers: n = 6, 50%)
  • Absence seizures:
    1. Persist in fewer than half of cases into adulthood (PHYSICIANS: n = 14, 86%; caregivers : n = 6, 67%)
  • Atonic seizures:
    1. Persist in fewer than half of cases into adulthood (PHYSICIANS: n = 14, 100%; CAREGIVERS: n = 5, 100%)
  • Tonic seizures:
    1. Persist in fewer than half of cases into adulthood (PHYSICIANS: n = 15, 80%)
    2. Persist in more than half of cases into adulthood ( caregivers : n = 7, 71%)
  • Brief (<5 min) generalized tonic–clonic seizures:
    1. Persist in more than half of cases into adulthood (PHYSICIANS: n = 15, 93%; CAREGIVERS: n = 7, 86%)
  • Focal impaired awareness seizures:
    1. No consensus (physicians or caregivers)
  • Brief (<5 min) focal motor seizures:
    1. No consensus (physicians)
    2. Persist in fewer than half of cases into adulthood ( caregivers : n = 6, 67%)
  • Prolonged (5–29 min) convulsive seizures
    1. Persist in fewer than half of cases into adulthood (PHYSICIANS: n = 14, 86%; caregivers : n = 7, 71%)
  • Convulsive status epilepticus (≥30 min):
    1. Persists in fewer than half of cases into adulthood (PHYSICIANS: n = 15, 93%; CAREGIVERS: n = 6, 100%)
  • Nonconvulsive status epilepticus:
    1. Persists in fewer than half of cases into adulthood (PHYSICIANS: n = 14, 100%; caregivers a : n = 3, 67%)
Genetic testing
  • Provided the cost of an epilepsy gene panel is similar to SCN1A targeted testing, an epilepsy gene panel is the preferred genetic study for young children with suspected DS (PHYSICIANS: n = 20, 90%).
  • SCN1A pathogenic variants are detected in >85% of DS patients (PHYSICIANS: n = 19, 95%).
Neuroimaging
  • Brain MRI is typically normal at diagnosis (PHYSICIANS: n = 19, 100%).
  • With time, variable degrees of cortical atrophy may be seen on MRI; however, this may not be recognized, as serial MRI is typically not performed in persons with DS (PHYSICIANS: n = 20, 85%).
  • Hippocampal sclerosis may develop over time in a minority of cases (PHYSICIANS: n = 19, 100%).
EEG
  • With the exception of postictal slowing, the EEG background is typically normal prior to 12 months of age (PHYSICIANS: n = 19, 100%).
  • In persons 5 years and older, background slowing is present in most cases (PHYSICIANS: n = 19, 89%).
  • Interictal discharges are seen in fewer than half of cases before 12 months of age (PHYSICIANS: n = 19, 95%).
  • Interictal discharges are seen in most cases by 5 years of age (PHYSICIANS: n = 19, 100%).
  • Interictal discharges may be focal, multifocal, and/or generalized (PHYSICIANS: n = 19, 100%).
  • Up to half of persons with DS show a photoparoxysmal response on EEG at some point over their disease course. This finding may be age dependent and abate with time (PHYSICIANS: n = 20, 80%).
  • Recorded seizures are often “falsely generalized,” meaning that changes may appear bilateral on EEG early in a seizure that is clinically focal, or may appear bilateral at onset and then become and remain asymmetric (PHYSICIANS: n = 18, 94%).
  • Recorded seizures may be “unstable,” meaning that the epileptiform discharge changes topographically, moving from one brain region to another during the same seizure (PHYSICIANS: n = 17, 88%).
  • A minority of adolescents with DS may develop bifrontal spike‐and‐slow‐wave with generalized polyspikes in sleep, which correlate with axial tonic seizures ( physicians : n = 18, 67%).

Bold and all‐capital text indicates Strong consensus; bold and italic text indicates Moderate consensus; nonbold and italic text indicates no consensus.

Abbreviations: DS, Dravet syndrome; EEG, electroencephalography; MRI, magnetic resonance imaging.

a

Consensus was not determined for statements where >50% of the group did not provide a response.