Insular Seizures Often Start With Sudden Complex Movements

What was studied

This paper was a systematic review, which means the authors searched past medical reports and retrospective case series to look for patterns. They focused on people with epilepsy whose seizures started in the insula alone ("pure insular") or in the insula plus nearby opercular brain areas ("insulo-opercular"), and who had hyperkinetic seizures, meaning seizures with large or complex body movements.

The review searched several medical databases for studies published from 1969 to January 10, 2025. To be included, patients had to have seizure onset documented with invasive brain recordings such as SEEG or subdural electrodes, and they had to have at least 6 months of follow-up after surgery with Engel class I outcome. In the end, 14 studies with 34 patients were included.

What they found

Among the 34 patients, 61.8% had seizures starting in the insula alone. The most common etiology was focal cortical dysplasia, present in about two-thirds of cases. In most patients, the seizure began with non-motor symptoms before the hyperkinetic movements.

The review found that certain complex hyperkinetic behaviors were reported more often with pure insular onset than with insulo-opercular onset. These included integrated or natural hyperkinetic behaviors, as well as agitation, vocalization, and breathing difficulties. The authors concluded that hyperkinetic seizures were more frequently associated with pure insular onset, but they stressed that the evidence is exploratory and should be interpreted cautiously.

Limits of the evidence

This review was based on only 34 patients from 14 studies, so the sample was very small. The studies were also heterogeneous, which makes comparisons less reliable.

Because the review only included reported cases and retrospective series, it cannot establish that pure insular onset causes these seizure behaviors. It also only included patients whose seizure onset was documented with invasive monitoring and who had Engel class I postsurgical outcomes, so the findings may not apply to all people with insular epilepsy. Some percentages are based on very small numbers, so they should be interpreted with caution.

For families and caregivers

For families, this study suggests that seizures with dramatic, complex movements can occur in people with seizures starting in the insula or nearby opercular regions. It also suggests that breathing changes, vocal sounds, agitation, or more natural-looking movements may be reported more often in seizures starting in the insula alone.

This may matter because seizure behavior by itself can be misleading, and careful testing may be needed to help identify where seizures start. Still, this review does not change care on its own, and it does not show that these patterns are present in every child or adult with hyperkinetic seizures.

What to watch next

Stronger evidence would come from larger studies with more patients with insular and insulo-opercular epilepsy, including broader patient groups rather than only those with Engel class I surgery outcomes.

Terms in this summary

systematic review

A study that collects and summarizes results from many earlier studies using a planned search method.

insula

A part of the brain deep inside the side of the brain that can be involved in seizures.

operculum

Brain areas that cover the insula and sit next to it.

hyperkinetic seizures

Seizures with large, forceful, restless, or complex body movements.

semiology

The visible and felt features of a seizure, such as movements, sounds, or sensations.

focal cortical dysplasia

A brain development difference in one area of the brain that can be associated with seizures.

SEEG

A test that uses thin electrodes placed in the brain to find where seizures start.

Engel class I

A postsurgical seizure outcome category indicating the best outcome group.