Seizures in Adolescents: Motor or Nonmotor?

By Robert McInnis, MD

Assistant Professor of Clinical Neurology, Weill Cornell Medical College

SYNOPSIS: The rate at which motor vs. nonmotor seizures are recognized in adolescents is unknown. This retrospective analysis demonstrates a high rate of misrecognition of nonmotor seizures among adolescents presenting to an emergency department and frequent misrecognition of any nonmotor seizures in those presenting with a first-time motor seizure.

SOURCE: Jandhyala N, Ferrer M, Pellinen J, et al; Human Epilepsy Project Investigators. Unrecognized focal nonmotor seizures in adolescents presenting to emergency departments. Neurology 2024;102:e209389.

The emergency department (ED) is a common presenting location for both adult and pediatric patients with undiagnosed epilepsy to seek care for seizures. Motor seizures (those featuring prominent movements) may be readily recognized and lead to diagnosis, while nonmotor seizures (those featuring perceptual symptoms and/or impairment of awareness) may evade recognition, leading to delayed diagnosis and treatment and potentially increasing the risk of seizure-related morbidity. The rate at which motor vs. nonmotor seizures are recognized in the ED is unknown within the adolescent population.

To address this knowledge gap, the authors performed a retrospective analysis of data from the Human Epilepsy Project (HEP), enrolling patients 12 years of age and older seen at one of 34 study sites. Patients were enrolled within four months of initiation of treatment for focal epilepsy, with confirmation by an epilepsy specialist. Patients also met the inclusion and exclusion criteria for HEP. Inclusion required electroencephalogram or magnetic resonance imaging findings supportive of epilepsy in cases in which a patient had not had two or more unprovoked prior seizures. Patients with generalized, presumed, or confirmed genetic epilepsies; mixed epilepsy syndromes; epilepsy etiologies involving significant gliosis or brain injury; major medical comorbidities; autism diagnosis; moderate or greater degree of developmental delay before seizure onset; drug or alcohol abuse history; antiseizure medication given for another indication at or above a therapeutic dose; seizures only during pregnancy; or a comorbid psychiatric disorder that would interfere with study protocol were excluded.

The authors separated the study population into groups that presented to the ED before enrollment and those who did not. For participants who presented to an ED, adolescents aged 12-18 years were compared to those > 18 years of age. For each patient, clinical notes were reviewed to determine whether the presenting seizure type was identified correctly and whether any prior seizures were identified at the time of ED presentation. Seizure semiology was simplified into a binary classification of motor vs. nonmotor seizure types. Patients also were sorted into two groups based on whether the first lifetime seizure was a motor or nonmotor type.

There were 83 patients ≤ 18 years of age at the time of enrollment; 58 patients (70%) presented to an ED for evaluation of undiagnosed focal epilepsy, with a median age of enrollment of 14 years and with median age of onset of 13 years. Among those with nonmotor seizures at epilepsy onset, 26 of 44 patients (53%) presented to the ED. Of those who presented to the ED, a minority of four patients presented with a first lifetime nonmotor seizure.

The 22 other patients (85%) had seizures prior to ED presentation, of which the majority (17 [65%]) presented to the ED with a first motor seizure after previously experiencing only nonmotor seizures. The rest of the patients had prior mixed motor and nonmotor seizures. Patients with motor seizures at epilepsy onset were significantly more likely to present to the ED compared to those with nonmotor seizures at onset (82% vs. 59%). Most ED presentations (52 of 58 [90%]) were for motor seizures, although a large subset had a history of nonmotor seizures (20 of 52 [38%]).

ED recognition of nonmotor seizures was poor. Those presenting with nonmotor seizures were significantly less likely to receive correct identification than those with motor seizures (33% vs. 81%). The majority of nonmotor seizures were categorized incorrectly with other labels, such as gastrointestinal complaints or anxiety, representing missed diagnoses. There were 17 patients who presented with a motor seizure but had a history of prior nonmotor seizures; none of these patients with prior nonmotor seizures were identified, in contrast to the adult comparator group in whom 23% of patients with prior nonmotor seizures were identified correctly.

COMMENTARY

Delayed diagnosis of focal epilepsy is a significant problem given the potential for harm associated with both motor and nonmotor seizures when antiseizure medications usually are effective for prevention. The adolescent population may be particularly vulnerable to these risks. This retrospective analysis highlights a high rate of misrecognition of nonmotor seizures among adolescents presenting with nonmotor seizures, and complete misrecognition of any nonmotor seizures prior to ED presentation. These findings are valuable in pinpointing ways to improve interviewing for patients who present to the ED with possible seizures, potentially leading to more rapid diagnosis.