Seizures in Children

Seizures occur when uncontrolled excessive synchronous neuronal activity in the brain causes sudden transient changes in motor function, sensation, behavior, or mental status. Seizures are classified primarily as generalized or focal and may occur once or be recurrent (epilepsy). Prolonged or recurrent seizures lasting > 30 minutes are called status epilepticus. Diagnosis depends on thorough history, physical exam, and EEG findings. Treatment is directed at the underlying trigger, and medications are administered as necessary. Most children that seize recover without any sequelae, but prognosis depends on the initial cause and the presence of underlying neurologic pathology.

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Overview

Definition

A seizure is an abnormal, excessive, and hypersynchronous firing of neurons in the brain.

  • Acute symptomatic or provoked seizures:
    • Occur secondary to alterations of the brain’s excitability
    • 2 main categories:
      • Structural: head injury, stroke, meningitis
      • Metabolic or toxic: electrolyte imbalance, poisoning
    • Occur within a week of inciting cause
  • Unprovoked seizures: 
    • Occur in absence of specific cause
    • If recurrent, defined as epilepsy
  • Reflex seizures:
    • Occur in response to a precipitating stimulus
    • Stimulus may be external, internal, or both:
      • External: flashing lights, auditory, tactile
      • Internal: emotions, thinking, calculations, or other cerebral functions
      • Sleep deprivation, emotional stress, and menstrual cycle are not considered triggering precipitants of epilepsy.
  • Recurrent seizures: childhood epilepsy
    • Risk factors for development of epilepsy:
      • Perinatal infections 
      • Prematurity
      • Hypoxic–ischemic injury at birth
      • Family history of seizures
      • History of febrile seizures
      • History of meningitis/encephalitis 
      • Head trauma

Epidemiology

  • Affect 1% of the population
  • Higher prevalence in rural areas and underdeveloped countries
  • Highest incidence in 1st year of life and decline to adult levels by ages 10–11 years
  • Febrile seizures affect 4%–10% of the population.
  • Only 15% of children who have a 1st seizure will have another in the next year.

Classification

Separating seizures into different types guides testing, treatment, and prognosis. The classification system was revised in 2017 by the International League Against Epilepsy and is now based on 3 key features: where the seizure begins in the brain, level of awareness during the seizure, and other features of seizure.

  • Location-based:
    • Generalized: begins in both sides of the brain
    • Focal (formerly called “partial”): begins in 1 area of the brain
    • Unknown: Area of onset of seizure is unknown.
    • Focal to bilateral: begins in 1 area of the brain and spreads to both sides (formerly called “secondary generalized”)
  • Level of awareness:
    • Focal aware (formerly called “simple partial”): conscious even if unresponsive during seizure
    • Focal impaired awareness (formerly called “complex partial”): if during seizure there is any diminished awareness or impaired consciousness
    • Awareness unknown: if unable to be determined
    • Generalized seizures are all presumed to cause a diminished level of consciousness.
  • Other features:
    • Automatisms or other movements during seizure
    • Changes in sensation, thinking, or emotions prior to seizure (formerly called “aura”)
    • The specific term “aura” has been removed from the new classification system.

Etiology

  • Most common:
    • Fever
    • Genetic 
    • Head injury 
    • Infections of the brain and its coverings
    • Lack of oxygen to the brain
    • Hydrocephalus 
    • Disorders of brain development
    • Metabolic disorders or inborn errors of metabolism
    • Toxins and poisoning
  • Less common: 
    • Brain tumors or cysts
    • Degenerative disorders
  • Many are benign, will not continue into adulthood, and have no long-term effect on child’s development and intellect is normal.

Mnemonic

“The hypos cause seizures”:

  • Hypocalcemia
  • Hypoglycemia
  • Hyponatremia
  • Hypomagnesemia

Status epilepticus

Definition:

  • Seizure lasting > 5 minutes or when seizures occur close together without return to normal level of awareness after the 1st seizure
  • Repeated seizure for ≥ 30 minutes
  • Types:
    • Convulsive
    • Nonconvulsive

Clinical findings:

  • Different neurologic symptoms depending on where in the brain the seizure originated
  • Alteration of vital signs and/or respiratory suppression
  • Postictal period in generalized seizures.
  • Todd’s paralysis: period of paralysis following seizure
  • Requires emergent medical treatment because condition is life-threatening

Treatment:

  • Medications
  • Oxygen or other respiratory support
  • Fluid resuscitation 
  • Diagnostic testing to determine underlying cause 
  • Continuous EEG monitoring

Generalized Seizures

Febrile seizures

  • Definition:  
    • A generalized convulsive episode in the context of febrile disease (> 38°C)
    • Classification:
      • Simple: last < 15 minutes and/or have no recurrence in 24 hours
      • Complex: last > 15 minutes and/or reoccur within the next 24 hours
  • Epidemiology:
    • Most common cause of seizures in children
    • Occur in children between 6 months and 6 years of age
    • Peak incidence: 12–18 months
    • 25% recurrence rate if over 1 year of age at 1st event
    • 50% recurrence rate if < 12 months of age at 1st event
    • Most common causes: viral infection, postvaccination
  • Diagnosis:  
    • Requires detailed history
    • Determine whether the episode meets the criteria for simple or complex classification.
  • Treatment:
    • Treat the fever. 
    • Look for underlying cause of fever.
    • Verify appropriate dosing of antipyretic with caregiver.
    • Counsel parents on what to do if seizures recur.
    • Use antiepileptic drugs if:
      • Seizure continues (status epilepticus)
      • Fever cannot be controlled
  • Complications:
    • Recurrence is common. 
    • Higher risk of recurrence if:
      • 1st seizure resulted from a low-grade fever
      • Seizure was the 1st sign of illness
      • Immediate family member has history of febrile seizures
      • Child < 18 months old at time of 1st febrile seizure
      • Child had history of developmental issues prior to seizure
    • Complex febrile seizures increase the chance of developing epilepsy.
  • Prognosis: Majority resolve without any neurologic sequelae unless seizure is focal or prolonged or child has other neurologic abnormalities.

Absence seizures

  • Definition: brief period of unresponsiveness 
    • Last about 4–30 seconds
    • Occur multiple times per day
    • Symptoms:
      • Staring
      • Eye fluttering
      • Pallor
    • No incontinence, aura, or postictal state
  • Epidemiology:
    • Generally ages 4–12 years
    • Peak age: 5–7 years
    • 60% have complete resolution of seizures by adolescence.
  • Classification: based on seizure characteristics and EEG pattern
    • Typical: sudden onset, brief duration with characteristic EEG
    • Atypical: insidious onset and resolution of symptoms with slower EEG pattern
  • Diagnosis: classic 3-Hz spike-and-wave discharges
  • Treatment: anticonvulsant medication
Eeg showing interictal spikes and polyspikes - tonic clonic seizure

EEG showing interictal spikes and polyspikes: tonic–clonic generalized seizure

Image: “EEG showing interictal spikes and polyspikes” by Central Military Emergency University Hospital, “Dr Carol Davila” Department of Neurology, Calea Plevnei 134, Bucharest, Romania. License: CC BY 2.0

Myoclonic seizures

  • Brief, jerking spasms of a muscle or muscle group
  • No loss of awareness
  • Often occur with atonic seizures
  • Associated epileptic syndromes:
    • Infantile spasms
    • Lennox–Gastaut syndrome

Atonic seizures (“drop attacks”)

  • Characterized by sudden loss of muscle tone
  • When there is total lack of muscle tone, body falls and additional injury may be sustained.
  • Consciousness is impaired during the fall.
  • Often associated with myoclonic seizures
  • Rare
  • Treated with anticonvulsants, nerve stimulation, diet therapy

Tonic seizures

  • Body, arms, or legs suddenly become stiff or tense.
  • Fully aware or mild change in awareness during seizure
  • Involve both sides of brain and, therefore, affect both sides of body
  • Short duration: < 20 seconds
  • Typically occur during sleep
  • Common in children with Lennox–Gastaut syndrome
  • Diagnosed with MRI and/or EEG
  • Treated with anticonvulsants, nerve stimulation, diet therapy
Eeg showing absence seizure

A: Bilateral synchronous regular 3-Hz spike-and-wave discharges in proband 1 lasting for 15 seconds and associated with clinical absence seizures
B: Absence seizure in proband 2 lasting for 4 seconds
C: Spike-and-wave discharges lasting for 3 seconds in proband 4: This proband was affected by absence status lasting for > 6 hours.

Image: “EEG recordings of 15q13.3 microdeletion carriers” by Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian-Albrechts University, Kiel, Germany. License: CC BY 2.5

Focal Seizures

  • Definition:
    • Seizure activity involving 1 area of the brain
    • Formerly known as “partial seizures”
  • Classification:
    • Level of awareness: preserved versus impaired 
    • Motor versus nonmotor
  • Focal with preserved awareness:
    • Formerly known as “simple partial seizures”
    • Start in 1 part of the brain while child is aware
    • Brief: last < 2 minutes
    • Motor most common
    • Jacksonian march:
      • Occur on 1 side of the body
      • Progress in a predictable pattern
      • Start as twitching or a tingling sensation or weakness in a finger, a big toe, or the corner of the mouth, then march over a few seconds to the all of the hand, foot, or facial muscles
  • Focal with impaired awareness:
    • Formerly known as “complex partial seizures”
    • Start in 1 area or side of the brain with loss of awareness
    • Brief: last 1–2 minutes
    • Preceded by aura
    • Automatism:
      • Lip smacking
      • Chewing
      • Bicycle leg movements
  • Focal to bilateral tonic–clonic:
    • Formerly known as “secondary generalized seizures”
    • Start in 1 area of the brain and then rapidly spread to both sides of brain
    • May begin with aura
    • 30% of children with focal seizures
    • Tonic–clonic portion is brief, lasting < 3 minutes.
    • Postictal period
  • Diagnosis:
    • EEG
    • MRI
  • Treatment:
    • Anticonvulsants
    • Implanted electrical devices
    • Ketogenic diet
    • Surgery

Epileptic Syndromes

Infantile spasms (West syndrome)

  • With activity, occur in clusters every 5–10 seconds over 5–10 minutes
  • Clusters often confused with colic because infant cries or is irritable during event
  • EEG shows classic hypsarrhythmia pattern.
  • Generalized seizure primarily in infant
  • Brief movements of the neck, trunk, and limbs 
  • Poor prognosis:
    • Profound cognitive effects
    • May resolve by preschool years, but other seizure types develop

Neonatal seizures

  • Neonatal period is the most vulnerable for developing seizures 
  • More common in preterm infants
  • 80% occur in 1st week of life.
  • Usually clinically subtle
  • No postictal state
  • Hypoxic–ischemic encephalopathy is the most common cause.
  • Development of subsequent epileptic syndrome is rare.

Benign Rolandic epilepsy

  • Also called “benign epilepsy with centrotemporal spikes”
  • Focal aware type of seizure:
    • When child awake, twitching, numbness, or tingling on 1 side of face or tongue
    • No impairment of awareness
  • 15% of all epileptic episodes in children
  • Begin 6–12 years of age
  • Boys more often affected
  • Usually occurs during sleep and evolves to involve both sides of body
  • Self-resolves by adolescence

Lennox–Gastaut syndrome

  • Severe form of epilepsy beginning in early childhood, usually before age 4 years
  • Multiple types of seizures; most commonly:
    • Tonic
    • Atypical absence
    • Atonic
    • Myoclonic
    • Generalized tonic–clonic
  • Majority have prolonged seizures (status epilepticus).
  • Associated cognitive impairment, developmental delay, and behavioral disturbances
  • Multiple causes; ⅓ have unknown cause
  • EEG pattern: slow spike and wave
  • Poor prognosis
Eeg of a child with lennox–gastaut syndrome

EEG of a child with Lennox–Gastaut syndrome

Image: “24 hour prolonged digital video EEG” by Max Superspecialty Hospital, Saket, New Delhi, India. License: CC BY 2.0

Evaluation

1st seizure:

  • Initial assessment of airway, breathing, and circulation
  • Determine if child is actively seizing, postictal, or at baseline mental status.
  • Establish IV access and administer rescue anticonvulsant medication if actively seizing.
  • Obtain vital signs to determine if febrile seizure is likely and to evaluate blood pressure (shock).
  • Obtaining a thorough history can assist with determining underlying cause, determining whether activity meets criteria for seizure, and classifying type of seizure:
    • Events surrounding suspected seizure
    • Length of seizure (if not actively seizing)
    • Specific movements or staring
    • Bowel or bladder incontinence
    • Loss of awareness during event
    • Postictal state
  • Keep in mind life-threatening causes and address immediately:
    • Meningitis
    • Sepsis
    • Head trauma
    • Accidental or intentional intoxication
  • Perform thorough physical examination:
    • Look for signs of trauma.
    • Fundoscopic exam:
      • Papilledema  
      • Retinal hemorrhages
      • Chorioretinitis
    • Neurologic examination:
      • Hemiparesis with hyperreflexia
      • Positive Babinski sign
  • Laboratory testing:
    • CMP
    • CBC 
    • Blood gas
    • Electrocardiography: long-QT syndrome
    • CSF analysis if suspicion for neurologic infection
    • EEG: 
      • In all cases of unprovoked, nonfebrile seizures
      • May determine underlying cause 
      • Patient must be stable.
    • CT allows for rapid study of trauma and masses.
    • MRI is preferred over CT for more careful studies.

Management

Treatment is based on a variety of factors. Not every child who has a seizure will have another one; therefore, treatment may be unnecessary until there is recurrence. The ultimate goal of treatment is to stop seizure activity while minimizing harmful side effects.

Medication

  • Anticonvulsants:
    • Many options: depend on type of seizure, frequency, age
    • Often need to try multiple medications before stabilization or optimal side effect management
  • Cannabidiol:
    • Recently FDA-approved for children age ≥ 2 years
    • Treats only certain types of seizures

Dietary therapy

  • Ketogenic diet:
    • High in fat, low in carbohydrates
    • Very restrictive
  • Variations on ketogenic diet under study

Surgery

  • Best option for seizures originating in the same place in the brain
  • Types of procedures:
    • Lobectomy
    • Corpus callosotomy
    • Hemispherectomy
    • Thermal ablation

Electrical stimulation

  • Implanted device that sends signals to brain to inhibit seizure activity
  • May be located in chest, on brain surface, or deep within brain tissue

References

  1. The Johns Hopkins Hospital Lauren Kahl Helen Hughes. (2018). Seizures: first and recurrent. In The Harriet Lane Handbook, 21st ed. Elsevier, pp. 555–564.
  2. Epilepsy Foundation. (2017). Revised Classification of Seizures. Retrieved April 1, 2021, from www.epilepsy.com.
  3. Camfield P, Camfield C. (2015). Incidence, prevalence, and etiology of seizures and epilepsy in children. In Epileptic Disorders, pp. 117–123. Retrieved April 2, 2021, from https://pubmed.ncbi.nlm.nih.gov/25895502/

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