Pathognomonic EEG Patterns

Epilepsy Syndromes

• Epilepsy syndrome: a group of signs or symptoms that help identify a unique medical condition, characterized by specific signs or symptoms, type of seizure(s), age when seizures start, and pattern on EEG.
• Types of epilepsy syndromes:
  • Symptomatic/Encephalopathic
  • Progressive and Infantile Myoclonic Epilepsies
  • Focal
  • Idiopathic
  • Febrile Seizure

Infantile Spasms and West Syndrome

• Infantile Spasms: flexor, extensor, lightning, or nods—most are mixed, onset 4-8 months, peak 5 mo.
• West Syndrome: triad of infantile spasms, hypsarrhythmia, and developmental delay, onset 4-7 months, always before 1 year old, boys>girls.
• Etiology: 75-85% symptomatic, 15-25% asymptomatic, underlying conditions include genetic, metabolic, congenital infection, and neonatal infection.
• Treatment: steroids, vigabatrin, ketogenic diet, zonisamide, vitamin B6, prognosis partly based on early treatment, but typically poor.

Lennox-Gastaut Syndrome

• Triad: multiple seizures types, cognitive dysfunction, and slow GSW (1.5-2 Hz) on EEG.
• Onset: 1-8 years, typically 3-5 yr, 10-25% cases preceded by infantile spasms.
• Causes: 70-78% structural/metabolic, 30-22% unknown, family history of epilepsy in 3-30%.
• Prognosis: overall refractory to ASDs and poor prognosis.

Severe Myoclonic Epilepsy of Infancy (SMEI)

• Prolonged febrile seizures in the 1st year of life, seizure-free period followed by myoclonic seizures at 1-4 yr old.
• Normal early development, then later deterioration, pyramidal signs and ataxia.
• EEG: slow SW, polyspike-and-wave, 70-80% mutation in SCN1A.

Myoclonic Astatic Epilepsy (MAE) or Doose Syndrome

• Type of generalized epilepsy, onset 1-5 years old.
• EEG: 2-3 Hz gen SW, polyspike and 4-7 Hz central/vertex rhythmic theta activity.
• MRI: normal, associated with SCN1A mutation, boys>girls (2:1).
• Prognosis: typically poor with severe intellectual disability, ataxia, poor motor function, dysarthria, and poor language development.

Epileptic Encephalopathy with Continuous Spike and Wave During Sleep (CSWS)

• Epileptiform activity occupying >85% of NREM sleep, 2 syndromes: Landau-Kleffner Syndrome (LKS) and CSWS.
• Landau-Kleffner Syndrome: typically age 3-10 y, sudden or gradual aphasia, verbal auditory agnosia, 2/3rd have seizures, ADHD.
• CSWS: global regression in cognition and behavior, majority of patients have seizures, may have identifiable pathology.

Panayiotopolous Syndrome (Early Childhood Onset “Occipital” Epilepsy)

• Seizures: behavioral agitation, headache, autonomic symptoms, and motor (hemi-clonic or GTC), prolonged and nocturnal (2/3).
• Interictal EEG: occipital spikes in sleep (classic), 85% have boys, frequent absence seizures (pyknolepsy).

Absence Epilepsy

• Not fully understood, abnormal oscillatory rhythms are believed to develop in thalamocortical pathways.
• Treatment: ethosuxamide, lamotrigine, valproic acid, double-blinded RCT compared the 3 and found ethosuxamide provides the best combo of seizure control and fewest attentional side effects.

Juvenile Absence Epilepsy

• Onset 10-17 years old, less frequent absence seizures, more associated with GTCs, less severe impairment in consciousness.

Juvenile Myoclonic Epilepsy

• Onset 12-18 years old, seizures upon awakening in AM or after nap, triggers: sleep deprivation, stress, fatigue, and alcohol.
• EEG: interictal high amplitude, generalized 4-6 Hz polyspike and wave, 30% have photosensitivity, 40-50% with family history.

Genetic Epilepsy and Febrile Seizures Plus (GEFS+)

• FS after 6 yr old OR occurrence of other seizure types, almost any type of seizure can occur, associated mutations SCN1A, SCN1B, GABRG2.

Epilepsy Disorders with Pathognomonic EEG Patterns

• Pathognomonic: of a sign or symptom, specifically characteristic or indicative of a particular disease or condition.
• Types of pathognomonic EEG patterns:
  • Periodic
  • Rhythmic
  • Other

Crutzfeldt-Jakob Disease (CJD)

• Rapidly progressive, invariably fatal neurodegenerative disorder, EEG: generalized periodic discharges, myoclonic jerks, and variations do occur.

Subacute Sclerosing Panencephalitis (SSPE)

• Progressive neurological disorder, EEG: generalized periodic discharges of longer interval than CJD, bilaterally synchronous, high-amplitude spike or slow-wave bursts.

Herpes Encephalitis

• Rare neurological disorder, EEG: lateralized periodic discharges (LPDs), bihemspheric independent discharges (BiPDs) are sometimes seen.

Anti-NMDA Receptor Encephalitis

• Autoimmune encephalitis, EEG: extreme delta brush, often seen with more prolonged illness.

Angelman Syndrome

• Neurodevelopmental disorder, EEG: notched delta, small interstitial deletion between 15q11 and 15q13, maternally derived.

Epilepsy Syndromes

• Epilepsy syndrome: a group of signs or symptoms that help identify a unique medical condition, characterized by specific signs or symptoms, type of seizure(s), age when seizures start, and pattern on EEG.
• Types of epilepsy syndromes:
  • Symptomatic/Encephalopathic
  • Progressive and Infantile Myoclonic Epilepsies
  • Focal
  • Idiopathic
  • Febrile Seizure

Infantile Spasms and West Syndrome

• Infantile Spasms: flexor, extensor, lightning, or nods—most are mixed, onset 4-8 months, peak 5 mo.
• West Syndrome: triad of infantile spasms, hypsarrhythmia, and developmental delay, onset 4-7 months, always before 1 year old, boys>girls.
• Etiology: 75-85% symptomatic, 15-25% asymptomatic, underlying conditions include genetic, metabolic, congenital infection, and neonatal infection.
• Treatment: steroids, vigabatrin, ketogenic diet, zonisamide, vitamin B6, prognosis partly based on early treatment, but typically poor.

Lennox-Gastaut Syndrome

• Triad: multiple seizures types, cognitive dysfunction, and slow GSW (1.5-2 Hz) on EEG.
• Onset: 1-8 years, typically 3-5 yr, 10-25% cases preceded by infantile spasms.
• Causes: 70-78% structural/metabolic, 30-22% unknown, family history of epilepsy in 3-30%.
• Prognosis: overall refractory to ASDs and poor prognosis.

Severe Myoclonic Epilepsy of Infancy (SMEI)

• Prolonged febrile seizures in the 1st year of life, seizure-free period followed by myoclonic seizures at 1-4 yr old.
• Normal early development, then later deterioration, pyramidal signs and ataxia.
• EEG: slow SW, polyspike-and-wave, 70-80% mutation in SCN1A.

Myoclonic Astatic Epilepsy (MAE) or Doose Syndrome

• Type of generalized epilepsy, onset 1-5 years old.
• EEG: 2-3 Hz gen SW, polyspike and 4-7 Hz central/vertex rhythmic theta activity.
• MRI: normal, associated with SCN1A mutation, boys>girls (2:1).
• Prognosis: typically poor with severe intellectual disability, ataxia, poor motor function, dysarthria, and poor language development.

Epileptic Encephalopathy with Continuous Spike and Wave During Sleep (CSWS)

• Epileptiform activity occupying >85% of NREM sleep, 2 syndromes: Landau-Kleffner Syndrome (LKS) and CSWS.
• Landau-Kleffner Syndrome: typically age 3-10 y, sudden or gradual aphasia, verbal auditory agnosia, 2/3rd have seizures, ADHD.
• CSWS: global regression in cognition and behavior, majority of patients have seizures, may have identifiable pathology.

Panayiotopolous Syndrome (Early Childhood Onset “Occipital” Epilepsy)

• Seizures: behavioral agitation, headache, autonomic symptoms, and motor (hemi-clonic or GTC), prolonged and nocturnal (2/3).
• Interictal EEG: occipital spikes in sleep (classic), 85% have boys, frequent absence seizures (pyknolepsy).

Absence Epilepsy

• Not fully understood, abnormal oscillatory rhythms are believed to develop in thalamocortical pathways.
• Treatment: ethosuxamide, lamotrigine, valproic acid, double-blinded RCT compared the 3 and found ethosuxamide provides the best combo of seizure control and fewest attentional side effects.

Juvenile Absence Epilepsy

• Onset 10-17 years old, less frequent absence seizures, more associated with GTCs, less severe impairment in consciousness.

Juvenile Myoclonic Epilepsy

• Onset 12-18 years old, seizures upon awakening in AM or after nap, triggers: sleep deprivation, stress, fatigue, and alcohol.
• EEG: interictal high amplitude, generalized 4-6 Hz polyspike and wave, 30% have photosensitivity, 40-50% with family history.

Genetic Epilepsy and Febrile Seizures Plus (GEFS+)

• FS after 6 yr old OR occurrence of other seizure types, almost any type of seizure can occur, associated mutations SCN1A, SCN1B, GABRG2.

Epilepsy Disorders with Pathognomonic EEG Patterns

• Pathognomonic: of a sign or symptom, specifically characteristic or indicative of a particular disease or condition.
• Types of pathognomonic EEG patterns:
  • Periodic
  • Rhythmic
  • Other

Crutzfeldt-Jakob Disease (CJD)

• Rapidly progressive, invariably fatal neurodegenerative disorder, EEG: generalized periodic discharges, myoclonic jerks, and variations do occur.

Subacute Sclerosing Panencephalitis (SSPE)

• Progressive neurological disorder, EEG: generalized periodic discharges of longer interval than CJD, bilaterally synchronous, high-amplitude spike or slow-wave bursts.

Herpes Encephalitis

• Rare neurological disorder, EEG: lateralized periodic discharges (LPDs), bihemspheric independent discharges (BiPDs) are sometimes seen.

Anti-NMDA Receptor Encephalitis

• Autoimmune encephalitis, EEG: extreme delta brush, often seen with more prolonged illness.

Angelman Syndrome

• Neurodevelopmental disorder, EEG: notched delta, small interstitial deletion between 15q11 and 15q13, maternally derived.

This quiz covers epilepsy syndromes and disorders, including pathognomonic EEG patterns, from pediatric to adulthood. Learn about epilepsy syndromes and their definitions.