Seizures and Epilepsy: Classification, Diagnosis, and Management

Seizures represent a fundamental disruption of normal brain function, characterized by abnormal, excessive, and synchronized neuronal discharges. Understanding the distinction between seizures and epilepsy is crucial for proper diagnosis and management.

Seizure Definition and Pathophysiology A seizure is a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. The underlying mechanism involves an imbalance between excitatory (glutamate, aspartate) and inhibitory (GABA, glycine) neurotransmission, leading to neuronal hyperexcitability.

Epilepsy Definition Epilepsy is defined by any of the following conditions:

• At least two unprovoked seizures occurring >24 hours apart
• One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (≥60%) after two unprovoked seizures
• Diagnosis of an epilepsy syndrome

Epidemiology and Impact Epilepsy affects approximately 1-2% of the global population, with an annual incidence of 50-70 per 100,000 people. The condition exhibits a bimodal age distribution, with peaks in childhood and elderly populations. The economic burden includes direct medical costs, indirect costs from reduced productivity, and significant psychosocial impacts.

Risk Factors and Etiology Common risk factors include:

• Genetic predisposition (family history)
• Structural abnormalities (head trauma, stroke, tumors)
• Metabolic disorders (hypoglycemia, electrolyte imbalances)
• Infections (meningitis, encephalitis)
• Developmental disorders
• Drug withdrawal or toxicity

Seizure Threshold Concept Every individual has a seizure threshold - the level of stimulation required to trigger a seizure. This threshold can be lowered by factors such as sleep deprivation, alcohol withdrawal, metabolic disturbances, medications, and stress. Understanding this concept is essential for both treatment and prevention strategies.

The International League Against Epilepsy (ILAE) 2017 classification system provides a comprehensive framework for categorizing seizures based on their onset, awareness level, and motor features.

Three-Level Classification Structure

Level 1: Seizure Types

• Focal seizures: Originate in networks limited to one hemisphere
• Generalized seizures: Originate at some point within and rapidly engage bilaterally distributed networks
• Unknown onset: When the onset cannot be determined

Focal Seizures Classification

Generalized Seizures Classification

• Motor: Tonic-clonic, clonic, tonic, myoclonic, myoclonic-tonic-clonic, myoclonic-atonic, atonic, epileptic spasms
• Non-motor (absence): Typical absence, atypical absence, myoclonic absence, eyelid myoclonia

Level 2: Epilepsy Types

• Focal epilepsy
• Generalized epilepsy
• Combined generalized and focal epilepsy
• Unknown epilepsy

Level 3: Epilepsy Syndromes Specific epilepsy syndromes are characterized by typical age of onset, seizure types, EEG findings, and prognosis. Examples include:

• Childhood absence epilepsy
• Juvenile myoclonic epilepsy
• Temporal lobe epilepsy
• West syndrome (infantile spasms)

Clinical Significance Accurate classification is essential for:

• Appropriate antiepileptic drug selection
• Prognosis determination
• Genetic counseling
• Surgical candidacy assessment
• Treatment response prediction

Electroencephalography (EEG) remains the primary diagnostic tool for seizure evaluation, providing crucial information about seizure type, localization, and treatment response.

Normal EEG Patterns Understanding normal EEG patterns is essential for recognizing abnormalities:

• Alpha rhythm: 8-13 Hz, posterior-dominant, reactive to eye opening
• Beta rhythm: >13 Hz, frontal-central distribution
• Theta rhythm: 4-8 Hz, normal in children, abnormal if excessive in adults
• Delta rhythm: <4 Hz, normal during sleep, abnormal when awake

Interictal EEG Abnormalities

Ictal EEG Patterns

• Focal seizures: Rhythmic activity beginning focally, may spread
• Generalized tonic-clonic: Generalized fast activity followed by spike-wave complexes
• Absence seizures: Generalized 3-Hz spike-wave complexes
• Myoclonic seizures: Generalized polyspike-wave complexes

Special EEG Techniques

• Activation procedures: Hyperventilation, photic stimulation, sleep deprivation
• Video-EEG monitoring: Gold standard for capturing seizure events
• Ambulatory EEG: Long-term outpatient monitoring
• Invasive monitoring: Intracranial electrodes for surgical candidates

EEG Interpretation Principles

1. Consider patient age and clinical context
2. Assess background activity symmetry and reactivity
3. Identify epileptiform vs. non-epileptiform abnormalities
4. Correlate with clinical semiology
5. Multiple EEGs may be necessary (yield increases with repetition)

Limitations

• Single routine EEG detects epileptiform abnormalities in only 50% of epilepsy patients
• False positives occur in 1-2% of normal population
• Subclinical seizures may be missed
• Technical artifacts can mimic seizure activity

Status epilepticus (SE) represents a neurological emergency requiring immediate recognition and aggressive treatment to prevent permanent neurological damage and death.

Definition and Classification Status epilepticus is defined as:

• Continuous seizure activity ≥5 minutes, OR
• Recurrent seizures without recovery of consciousness between episodes

The ILAE recognizes four axes of classification:

1. Semiology: Convulsive vs. non-convulsive
2. Etiology: Acute symptomatic, remote symptomatic, progressive, unknown
3. EEG correlates: Electrographic patterns
4. Age: Neonatal, infant, child, adolescent, adult, elderly

Types of Status Epilepticus

Emergency Management Algorithm

STATUS EPILEPTICUS MANAGEMENT

Time 0-5 minutes: ├── Assess ABCs (Airway, Breathing, Circulation) ├── IV access, O2, cardiac monitoring ├── Check glucose, electrolytes └── Consider thiamine if alcohol use suspected

Time 5-10 minutes (First-line): ├── Benzodiazepines (choose one): │ ├── Lorazepam 0.1 mg/kg IV (max 4mg) │ ├── Diazepam 0.2 mg/kg IV (max 10mg) │ └── Midazolam 0.2 mg/kg IM/IV (max 10mg) └── May repeat once after 5 minutes

Time 10-30 minutes (Second-line): ├── If IV access available: │ ├── Fosphenytoin 20 PE/kg IV (150 PE/min) │ ├── Phenytoin 20 mg/kg IV (50 mg/min) │ ├── Valproic acid 40 mg/kg IV │ └── Levetiracetam 60 mg/kg IV └── If no IV: Midazolam 0.2 mg/kg IM

Time >30 minutes (Third-line/Refractory): ├── ICU admission required ├── Continuous EEG monitoring └── Anesthetic agents: ├── Propofol 2-10 mg/kg/hr ├── Midazolam 0.2-2 mg/kg/hr └── Pentobarbital 5-50 mg/kg/hr

Complications and Monitoring

• Systemic: Hyperthermia, rhabdomyolysis, cardiac arrhythmias, pulmonary edema
• Neurological: Cerebral edema, increased ICP, permanent neuronal damage
• Metabolic: Lactic acidosis, hyperkalemia, hypoglycemia

Prognosis Factors

• Duration of SE (most important)
• Age (worse in elderly)
• Underlying etiology
• Response to initial treatment

Antiepileptic drug (AED) selection requires careful consideration of seizure type, patient factors, drug characteristics, and potential adverse effects. Modern epilepsy management follows evidence-based algorithms to optimize seizure control while minimizing side effects.

First-Line AED Selection by Seizure Type

AED Selection Algorithm

AED SELECTION PROCESS

1. Determine Seizure Type ├── Focal → Carbamazepine/Lamotrigine/Levetiracetam └── Generalized → Valproic acid/Lamotrigine/Levetiracetam

2. Consider Patient Factors ├── Age (pediatric vs. adult vs. elderly) ├── Sex (teratogenicity, contraception) ├── Comorbidities (liver, kidney, cardiac) ├── Concomitant medications (drug interactions) └── Lifestyle factors (adherence, cost)

3. Evaluate Drug Characteristics ├── Efficacy profile ├── Side effect profile ├── Drug interactions ├── Dosing frequency └── Monitoring requirements

4. Initiate and Titrate ├── Start low dose ├── Titrate slowly ├── Monitor for efficacy and toxicity └── Adjust based on response

Special Populations

Women of Childbearing Age

• Avoid valproic acid (teratogenic)
• Folic acid supplementation 5mg daily
• Monitor drug levels during pregnancy
• Consider lamotrigine or levetiracetam

Elderly Patients

• Start with lower doses
• Slower titration schedules
• Monitor for drug interactions
• Consider pharmacokinetic changes
• Preferred: lamotrigine, levetiracetam

Pediatric Considerations

• Weight-based dosing
• Age-specific syndromes
• Cognitive side effects more prominent
• Growth and development considerations

Therapeutic Drug Monitoring Indications for level monitoring:

• Suspected non-adherence
• Breakthrough seizures
• Dose-related side effects
• Drug interactions
• Pregnancy
• Routine monitoring not recommended for newer AEDs

Treatment-Resistant Epilepsy Defined as failure of adequate trials of two tolerated, appropriately chosen AEDs.

Management options:

• Additional AED trials
• Combination therapy
• Epilepsy surgery evaluation
• Vagus nerve stimulation
• Ketogenic diet
• Responsive neurostimulation

A systematic approach to seizure evaluation is essential for accurate diagnosis, appropriate treatment selection, and optimal patient outcomes. The diagnostic workup must differentiate between seizures and seizure mimics while identifying underlying etiologies.

Initial Clinical Assessment

History Taking (Critical Components)

• Seizure semiology: Detailed description of ictal events
• Precipitating factors: Sleep deprivation, alcohol, medications, stress
• Aura description: Helps localize seizure onset
• Postictal state: Duration and characteristics
• Frequency and timing: Circadian patterns, clustering
• Witness accounts: Often more reliable than patient recall
• Family history: Genetic predisposition assessment
• Past medical history: Risk factors for secondary epilepsy

Physical Examination

• General examination for systemic diseases
• Neurological examination focusing on:
  • Mental status and cognitive function
  • Focal neurological deficits
  • Signs of increased intracranial pressure
  • Neurocutaneous stigmata
  • Evidence of head trauma

Diagnostic Testing Algorithm

DIAGNOSTIC WORKUP FOR SEIZURES

First Seizure: ├── Immediate (Emergency Department) │ ├── Blood glucose, electrolytes, CBC │ ├── Toxicology screen if indicated │ ├── Neuroimaging if focal features │ └── EEG (preferably within 24-48 hours) │ ├── Outpatient Follow-up │ ├── Routine EEG if not done acutely │ ├── MRI brain with epilepsy protocol │ └── Additional testing based on clinical suspicion │ Recurrent Seizures/Epilepsy: ├── Standard Workup │ ├── EEG (routine, may need multiple) │ ├── MRI brain with epilepsy protocol │ └── Baseline laboratory studies │ ├── Advanced Testing (if indicated) │ ├── Video-EEG monitoring │ ├── Neuropsychological testing │ ├── Genetic testing │ └── Metabolic studies

Laboratory Studies

Routine Studies

• Complete blood count
• Comprehensive metabolic panel
• Liver function tests
• Thyroid function tests
• Pregnancy test (women of childbearing age)

Specialized Studies (When Indicated)

• Lumbar puncture (suspected CNS infection)
• Autoimmune encephalitis panel
• Genetic testing (suspected genetic epilepsy)
• Metabolic studies (suspected inborn errors)

Neuroimaging

MRI Brain with Epilepsy Protocol

• Sequences: T1, T2, FLAIR, DWI, T1 with gadolinium
• Thin cuts: 1-3mm slices through temporal lobes
• Coronal views: Essential for hippocampal evaluation
• Indications: All patients with focal seizures, first generalized seizure in adults

CT Brain

• Limited use in epilepsy workup
• Emergency setting for acute presentations
• Can detect hemorrhage, large masses, calcifications

Differential Diagnosis

Risk Stratification Factors influencing recurrence risk:

• EEG abnormalities (increases risk)
• Structural brain lesion (increases risk)
• Nocturnal seizures (increases risk)
• Normal EEG and exam (decreases risk)

Successful epilepsy management extends beyond seizure control to encompass quality of life, medication adherence, comorbidity management, and long-term monitoring strategies.

Treatment Goals and Principles

Primary Goals

• Complete seizure freedom with minimal side effects
• Optimal quality of life and psychosocial functioning
• Prevention of seizure-related injuries
• Minimization of drug-related adverse effects

Management Principles

• Individualized treatment approach
• Regular follow-up and monitoring
• Patient education and counseling
• Multidisciplinary team involvement
• Consideration of non-pharmacological interventions

Follow-up Schedule and Monitoring

LONG-TERM MONITORING SCHEDULE

Newly Diagnosed (First 6 months): ├── Every 4-6 weeks initially ├── Monitor for drug efficacy ├── Assess for side effects └── Dose adjustments as needed

Stable Patients: ├── Every 6-12 months ├── Seizure diary review ├── Medication adherence assessment ├── Laboratory monitoring (if indicated) └── Quality of life evaluation

Special Situations: ├── Breakthrough seizures → Immediate evaluation ├── Pregnancy → Monthly monitoring ├── Surgery candidates → Comprehensive evaluation └── Status epilepticus → ICU management

Medication Adherence Strategies

• Patient education about importance of adherence
• Simplified dosing regimens when possible
• Use of medication organizers
• Electronic reminders and apps
• Regular pharmacy refill monitoring
• Address barriers to adherence (cost, side effects)

Side Effect Management

Comorbidity Management

Psychiatric Comorbidities

• Depression (30-50% prevalence)
• Anxiety disorders (20-30% prevalence)
• Psychosis (rare but significant)
• Screening tools: PHQ-9, GAD-7

Cognitive Comorbidities

• Memory impairment
• Executive dysfunction
• Attention deficits
• Language difficulties

Social and Lifestyle Considerations

• Driving restrictions and regulations
• Employment considerations
• Educational accommodations
• Insurance and legal issues
• Family planning counseling

When to Consider Drug Withdrawal

Criteria for AED withdrawal:

• Seizure-free for ≥2 years
• Single drug therapy
• Normal neurological examination
• Normal EEG (strongly recommended)
• Patient understanding of risks

Withdrawal Process

• Gradual tapering over 3-6 months
• One drug at a time if on polytherapy
• Close monitoring during withdrawal
• Patient education about recurrence risk (25-40%)

Refractory Epilepsy Management

Surgical Evaluation Criteria

• Drug-resistant epilepsy
• Identifiable epileptogenic zone
• Acceptable risk-benefit ratio
• Motivated patient/family

Non-pharmacological Options

• Ketogenic diet (especially pediatric)
• Vagus nerve stimulation
• Responsive neurostimulation
• Deep brain stimulation
• Behavioral interventions