Unifying Concepts

Clinical Aspects of the Diagnosis of Epileptic Seizures

The clinician must investigate and corroborate key features of the history that help to better characterize seizures while distinguishing epileptic seizures from nonepileptic events. The most common nonepileptic paroxysmal events during childhood and adolescence are syncope, psychogenic nonepileptic events (PNES), pallid and cyanotic breath holding spells, reflux/Sandifer syndrome, self-gratification disorders, and paroxysmal nonepileptic motor disorders of sleep among others.

History and Physical Examination Findings That Help Characterize Seizures

Predisposing factors Pre-ictal semiology Seizure semiology Postictal semiology
Family history of seizures or epilepsy
Cognitive and developmental deficits
Precipitating events (trauma, fever, toxins, sleep deprivation, hyperventilation, flashing lights, etc)
Preexisting structural brain lesion
Aura (vision of lights or colors, epigastric rising sensation, etc)
Behavioral changes (ie, behavioral arrest/unresponsiveness or period of confusion)
Automatism (pill rolling, picking, lip smacking)
Lack of appetite
Order of appearance and duration of every semiologic component
Level of consciousness (ability to understand)
Motor activity (clonic, tonic, tonic clonic)
Sensory abnormality
Predominant side of occurrence of every component
Vocal output (cries, grunts, etc)
Stereotypical facial expressions (facial slackening, eyelid fluttering, staring, or eye deviation)
Autonomic features (tachycardia, pallor, sweating, piloerection)
Respiration pattern
Autonomic features (tachycardia, pallor, sweating, piloerection)
Falls or loss of tone
Total duration
Presence of rhythmicity and evolution in frequency of event
Partial paralysis
Muscular pain
Behavioral changes
Predominant side of every component
Presence of injury secondary to the seizure episode

The clinician should investigate these features in every patient with a suspected first unprovoked seizure.

Main Differential Features of Seizures, Syncope, and Psychogenic Nonepileptic Seizures

Events in the history that are suggestive of Before the event During the event After the event
Epileptic seizures Sleep deprivation
Toxic exposure
Toxic withdrawal
Exposure to lights or sounds
Sensory aura
Epigastric rising sensation
Lack of response to stimulia
Eyes generally opened; if closed, there is no resistance to passive openinga
Short duration (1 min or less)a
Vocalization, if present, consists of simple sounds (crying)
Prolonged period of altered consciousness (sleepiness, confusion, etc) until complete recoverya
Relatively frequent traumatic injurya
Tongue biting relatively frequent and present in the lateral side of the tonguea
There is no recall of the episode or the peri-ictal period
Breathing is frequently deep and prolongeda
Syncope Emotional stress
Prolonged standing
Dehydration, hunger, pain
Carotid sinus stimulation
Elevated intrathoracic pressure (micturition, cough)
Repeated movements, if present, occur once on the floor, not while standing
Brief loss of consciousness
Incontinence may occur
Uncommon postictal headache or postictal confusion
Rapid and complete return to baseline
Infrequent traumatic injury
Recall of the period around the episode
Tongue biting typically midline or at the tip of the tongue
Appearance in a particular context (presence of witnesses, presence of significant others, emotions)
Trance, dreamlike state
Distortion of perception
Sensation of death
Gradual onset
Sometimes the episode can be induced with certain maneuvers
Out-of-phase motor activity
Vocalization of complex and purposeful sounds (words)
Forceful closure of the eyes with resistance to passive eye opening
Fluctuating course
Violent movements
Long duration (generally more than 1 minute)
Trashing and grabbing behavior
Pelvic thrusting
Semipurposeful, goal-directed movements
Confused staring
Response to stimuli
Directed rage
Inconsistent state of altered consciousness (sleepiness, confusion, etc)
Shallow and rapid breathing
Recall of the episode
Correct but partial and feeble motor responses

aTypical characteristics of generalized motor seizures.



  1. Sansevere AJ, Avalone J, Strauss LD, Patel AA, Pinto A, Ramachandran M, Fernandez IS, Bergin AM, Kimia A, Pearl PL, Loddenkemper T. Diagnostic and Therapeutic Management of a First Unprovoked Seizure in Children and Adolescents With a Focus on the Revised Diagnostic Criteria for Epilepsy. J Child Neurol. 2017 Jul;32(8):774-788. [Medline]
  2. Gavvala JR, Schuele SU. New-Onset Seizure in Adults and Adolescents: A Review. JAMA. 2016 Dec 27;316(24):2657-2668. [Medline]
  3. Alessi N, Perucca P, McIntosh AM. Missed, mistaken, stalled: Identifying components of delay to diagnosis in epilepsy. Epilepsia. 2021 Jul;62(7):1494-1504. [Medline]


Created Oct 14, 2021.

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