Hypomotor Seizures in Infants and Children

Abstract

Summary:Purpose: Hypomotor seizures (characterized by diminished behavioral activity with indeterminate level of consciousness) have been identified as an important seizure type in infants. Our goal was to investigate further the clinical and EEG features of hypomotor seizures.Methods: We retrospectively reviewed 110 hypomotor seizures from 34 patients recorded with video-EEG.Results: Twenty-seven (79%) patients were younger than 48 months, and seven (21%) were aged 4 to 15 years. Seventy-one (64%) seizures had regional or lateralized EEG onset, arising predominantly from temporal or parietal lobe regions. The other 39 (35%) seizures had generalized onset, usually with abrupt onset of diffuse rhythmic high-amplitude theta activity or diffuse electrodecrement and only rarely (two patients) with slow spike-wave complexes or 3-Hz spike-wave complexes. Hypomotor seizures with generalized EEG onset were significantly shorter than those with regional or lateralized onset (p ‫ס‬ 0.01, GEE model). Unsustained head or eye movements and subtle mouth automatisms were commonly seen in hypomotor seizures with either focal or generalized onset. Seventeen percent of hypomotor seizures with focal onset evolved to include version of head and eyes or jerking of one arm, whereas 2% of generalized hypomotor seizures evolved to a cluster of spasms.Conclusions: Hypomotor seizures may be either focal or generalized. Regional EEG onsets were most often temporal or parietal, suggesting that focal hypomotor seizures may be a bland form of "complex partial" seizures with no or minimal automatisms, seen predominantly in infants. Generalized hypomotor seizures were rarely associated with an ictal pattern of generalized spike-wave complexes, suggesting a different mechanism from absence seizures seen later in life.

Posterior quadrant disconnection for refractory epilepsy: A case series

“…Hypomotor seizures without secondary generalization were predominantly observed in all the patients in the current series, as often observed in pediatric patients with early epilepsy. [ 3 4 ]…”

Does semiology tell us the origin of seizures consisting mainly of an alteration in consciousness?

“…All children aged <8 years were excluded because of the reported effect of age on the seizure semiology (Fogarasi et al., 2002). Seizures in severely mentally retarded patients were also not included because it is impossible to assess ictal consciousness in these individuals (Källen et al., 2002). Other seizure types (nondialeptic) occurring in these patients were not evaluated for the semiologic part of the study.…”

Epileptic seizure semiology in infants and children

“…Despite these maneuvers, obtaining precise knowledge about the level of consciousness may not be possible. Källén et al [32] also noted that level of consciousness was "universally impossible to assess" in infants younger than 48 months and in children who were nonverbal due to cognitive impairment. Other investigators have also acknowledged the challenges of differentiating baseline oral motor behaviors from those of ictal automatisms [33,34,24,35,25,26,36,37,32,38].…”

“…Källén et al [32] also noted that level of consciousness was "universally impossible to assess" in infants younger than 48 months and in children who were nonverbal due to cognitive impairment. Other investigators have also acknowledged the challenges of differentiating baseline oral motor behaviors from those of ictal automatisms [33,34,24,35,25,26,36,37,32,38]. Avoiding assumptions about the level of consciousness in infants and children ensures that hypothesis of the epileptogenic zone is based on reliable ictal symptomatology.…”