What is the difference between seizures, convulsions, and epilepsy?

Distinguishing Seizures, Convulsions, and Epilepsy

A seizure is a single transient event of abnormal electrical brain activity, convulsions refer specifically to the visible motor manifestations (rhythmic jerking movements) that may accompany certain seizure types, and epilepsy is a chronic disorder defined by recurrent unprovoked seizures or a single seizure with high recurrence risk. 1, 2

Core Definitions

Seizures

• Seizures are uncontrolled electrical discharges of neurons in the brain that represent a symptom rather than a disease itself 3
• They manifest as abnormal excessive or synchronous neuronal activity causing transient signs and/or symptoms 2
• Approximately 8-10% of the population will experience at least one seizure during their lifetime 1
• Seizures can result from infections, trauma, poisonings, hypoxia, metabolic abnormalities (hypoglycemia), fevers in children, or underlying neurological conditions 3

Convulsions

• Convulsions specifically describe the motor component of generalized tonic-clonic seizures—the visible full-body rhythmic jerking movements 3
• Not all seizures involve convulsions; focal seizures may present as jerking of only one extremity, abnormal facial movements, small repetitive movements, or staring spells without generalized convulsive activity 3
• The term "convulsion" is essentially a descriptive feature rather than a diagnostic category, referring to the coarse, rhythmic, synchronous jerking movements that characterize certain seizure types 1

Epilepsy

• Epilepsy is a chronic brain disorder characterized by an enduring predisposition to generate recurrent unprovoked seizures 2
• The International League Against Epilepsy defines epilepsy as meeting one of three criteria: 1, 4
  • At least two unprovoked seizures occurring more than 24 hours apart
  • One unprovoked seizure with a probability of recurrence similar to the general recurrence risk after two unprovoked seizures (>60% over 10 years)
  • Diagnosis of a specific epilepsy syndrome
• Active epilepsy affects approximately 1.2% of the US population (3.4 million people) and 50 million people worldwide 4

Critical Distinction: Provoked vs. Unprovoked Seizures

Provoked (Acute Symptomatic) Seizures

• Occur at the time of or within 7 days of an acute neurologic, systemic, metabolic, or toxic insult 1, 5
• Common causes include: 1
  • Electrolyte abnormalities (hyponatremia, hypocalcemia, hypomagnesemia)
  • Metabolic derangements (hypoglycemia, hyperglycemia, uremia)
  • Toxic ingestions and medication effects (tramadol, SSRIs)
  • Alcohol withdrawal
  • Acute CNS infections
  • Acute structural lesions (stroke, hemorrhage)
• These patients do NOT have epilepsy and should not receive long-term antiseizure medications—treatment focuses on correcting the underlying cause 1, 5

Unprovoked Seizures

• Occur without acute precipitating factors, either idiopathic or from remote causes (>7 days prior) 1
• Categories include remote symptomatic seizures (from prior brain insult), idiopathic seizures, and genetic epilepsy syndromes 1
• High-risk features for recurrence after first unprovoked seizure include: 1
  • History of prior brain insult
  • Epileptiform abnormalities on EEG
  • Structural lesion on neuroimaging

Clinical Manifestations and Classification

Generalized Tonic-Clonic Seizures (Convulsive)

• Affect large areas or both sides of the brain simultaneously with full-body rhythmic jerking and loss of consciousness 3
• These are the seizures most commonly associated with the term "convulsions" 3
• May be accompanied by urinary incontinence 3
• Followed by a postictal period with tiredness and confusion lasting several minutes 3

Focal Seizures (May or May Not Be Convulsive)

• Affect only one area of the brain and can present without generalized convulsive movements 3
• Manifestations include: 3
  • Jerking of only one extremity or one side of the body
  • Abnormal facial movements
  • Small repetitive movements
  • Staring spells (focal impaired awareness)
• Some focal seizures progress to generalized seizures 3
• Consciousness may or may not be impaired 3

Practical Clinical Implications

When to Suspect Epilepsy vs. Single Seizure

• A single provoked seizure does NOT constitute epilepsy—approximately 8% of first seizures have correctable metabolic abnormalities 1
• Epilepsy diagnosis requires either recurrent unprovoked seizures or high recurrence risk after a single event 1, 4
• Non-compliance with antiseizure medications is a significant risk factor for seizure recurrence in established epilepsy patients 1

Key Diagnostic Pitfall

• When uncertain about epilepsy diagnosis, it is better to postpone the diagnosis than to falsely diagnose it, given the significant psychosocial implications 1
• Urinary incontinence occurs in both seizures and syncope and should not be used as a distinguishing feature 1
• Eyewitnesses may incorrectly report movements, and synchronous jerks can occur in syncope, which may be misinterpreted as seizure activity 1

Emergency Indications

Activate emergency medical services for: 3

• First-time seizure
• Seizures lasting >5 minutes (status epilepticus)
• Multiple seizures without return to baseline between episodes
• Seizures occurring in water
• Seizures with traumatic injuries, difficulty breathing, or choking
• Seizure in infant <6 months of age
• Seizure in pregnant individuals
• Failure to return to baseline within 5-10 minutes after seizure stops