What are the signs that a patient with a history of epilepsy or no prior history of seizures might be experiencing seizures?

Signs That a Patient Might Be Experiencing Seizures

The most critical signs of an active seizure include altered or complete loss of consciousness with motor manifestations (tonic stiffening, rhythmic jerking movements), eye deviation, irregular breathing patterns, and lack of response to external stimuli including pain. 1, 2

Motor Signs During Active Seizures

Tonic-Clonic (Grand Mal) Seizures

• Tonic phase: sustained muscle rigidity with forceful extension of extremities, causing the patient to fall stiffly ("keeling over like a falling log") rather than collapsing flaccidly 1, 2
• The tonic phase typically lasts 10-20 seconds before transitioning to rhythmic jerking movements 2
• An "ictal cry" may occur at onset due to air being forcefully expelled through partially closed vocal cords, which strongly suggests epilepsy rather than other causes 1, 2
• Movements begin at the exact onset of unconsciousness in seizures, whereas in syncope movements (if present) start after loss of consciousness 1, 2
• Movements in seizures are typically symmetrical and synchronous, unlike the brief, asymmetrical movements seen in syncope 1, 2

Subtle Motor Signs

• Seizures can manifest subtly with only eye deviation, irregular respiratory patterns, or drooling—these are easily missed without careful observation 1, 2
• Facial or hand twitching may be the only visible manifestation in subtle status epilepticus, particularly in comatose patients after a prolonged generalized seizure 3
• Subtle motor status epilepticus often follows overt convulsive seizures and carries significantly higher mortality (p = 0.0003) 1

Consciousness and Responsiveness

Complete Loss of Consciousness

• Complete loss of consciousness with no response to verbal commands or pain stimuli occurs during tonic-clonic seizures because patients cannot process or react to external stimuli during the ictal phase 4, 2
• Eyes typically remain open during the tonic phase, which can be misleading 2
• Pupillary changes including dilation or poor responsiveness may occur 2

Altered Consciousness Without Complete Loss

• Brief episodes of staring lasting 5-15 seconds with impaired consciousness, no prodrome, and immediate return to baseline afterward most likely represent absence seizures 4
• Patients with absence seizures remain upright during attacks and do not fall, distinguishing them from other seizure types 1
• Complete impairment of consciousness occurs during absence episodes, with non-responsiveness to verbal commands 4

Nonconvulsive Status Epilepticus (NCSE)

• NCSE manifests primarily as altered mental status, confusion, or abnormal behavior without dramatic convulsions—it can only be definitively diagnosed with EEG 1, 3
• NCSE is relatively rare in patients with CNS infections presenting with encephalopathy, but should be considered in all patients with undiagnosed encephalopathy 1
• Absence status epilepticus and complex partial status epilepticus present with confusion or abnormal behavior, while subtle status epilepticus occurs in comatose patients 3

Duration and Recovery Patterns

Seizure Duration

• Duration of loss of consciousness >1 minute strongly suggests epileptic seizure rather than syncope 1
• Seizure duration averages 74-90 seconds, significantly longer than syncope which typically lasts <30 seconds 1
• Duration >5 minutes suggests psychogenic pseudosyncope or psychogenic non-epileptic seizures 1

Post-Ictal Period

• Prolonged confusion or sleepiness lasting more than a few minutes after regaining consciousness points to epilepsy rather than syncope 1, 2
• Patients gradually regain consciousness during the post-ictal state and may begin responding to stimuli only after the seizure has ended 2
• Muscle pain lasting hours to days after the event suggests seizure activity 1
• Amnesia, particularly retrograde amnesia, may occur especially in older patients 1

Associated Physical Signs

Respiratory Changes

• Irregular respiratory patterns or temporary cessation of breathing may occur 2
• Stertorous (snoring) breathing may develop during the seizure 2
• Face may become cyanotic (blue) due to respiratory arrest 2

Oral and Facial Signs

• Tongue biting on the lateral sides strongly indicates seizure, while tip biting (if it occurs) is more common in syncope 1, 2
• Increased salivation leading to drooling or frothing at the mouth 2

Autonomic Signs

• Pupillary dilation may occur 2
• In contrast, syncope typically presents with prodromal autonomic symptoms including sweating, pallor, nausea, visual changes, and lightheadedness 1

Critical Diagnostic Pitfalls

• A normal interictal EEG does not rule out epilepsy—clinical diagnosis takes precedence, with EEG interpretation in clinical context 4
• Hypoglycemia may precipitate seizures or posturing and should be excluded in cases presenting with seizure-like activity 2
• Movements during an episode do not automatically indicate seizure, as brief myoclonic movements can occur in syncope due to cerebral hypoperfusion 1
• EEG should be considered in all patients with undiagnosed encephalopathy to detect NCSE, as specific treatments are available 1
• In patients with epilepsy history, witnessed seizures in hospital settings may progress to subtle motor status epilepticus, which significantly increases mortality risk 1