Orris

Seizures most common foci and cluster seizures common in

Reading File
Finding Sources
Finding Sources
Finding Sources
Finding Sources
Reading File
Finding Sources
Reading File
Finding Sources
Reading File
Finding Sources
Finding Sources
Reading File
Here is a complete answer based on authoritative neurology and psychiatry textbooks:

Seizure Foci - Most Common

Most Common Epileptic Focus: Temporal Lobe

  • Most adults with epilepsy, regardless of seizure type, have an epileptic focus in the temporal lobe - specifically the mediobasal (mesial) temporal structures (hippocampus, amygdala, parahippocampal gyrus).
  • At least two-thirds of focal seizures with impaired awareness and generalized tonic-clonic seizures originate from these mediobasal temporal limbic structures.
  • Many apparent generalized tonic-clonic seizures are actually secondarily generalized from a temporal lobe focus without a clinically obvious preceding focal seizure.
(Kaplan & Sadock's Comprehensive Textbook of Psychiatry)

Pathological Basis

The most common pathologic finding in epilepsy is mediobasal temporal lobe lesions:
  • ~2/3 of epileptic adults have a temporal lobe focus
  • Of those, ~2/3 have mesial temporal sclerosis (pyramidal cell loss in hippocampus)
  • Another 20-25% with temporal lobe lesions have tumors (hamartomas, gangliogliomas)
  • The rest have traumatic scars or lack a distinct histologic lesion
(Kaplan & Sadock's Comprehensive Textbook of Psychiatry)

Other Important Foci

FocusAssociated Features
Temporal lobe (mesial)Most common; complex partial/focal seizures with impaired awareness, automatisms, aura of fear/deja vu/epigastric rising
Frontal lobeSupplementary motor area - bilateral tonic posturing; contralateral gaze deviation; some automatisms previously attributed to temporal lobe
Occipital lobeVisual aura, ictal eye movements
Parietal lobeSomatosensory aura

Cluster Seizures - Classic Association

Epileptic Spasms / Infantile Spasms (West Syndrome)

Cluster seizures are classically associated with epileptic spasms, particularly in West Syndrome:
  • Epileptic spasms (formerly "infantile spasms," also called salaam attacks) typically occur in clusters, recurring every 5-40 seconds
  • In a cluster, initial spasms are subtle, increase in intensity as the cluster progresses, then decrease toward the end
  • Classic pattern: neck/trunk flexion + arm abduction (jackknife pattern); extension may also be seen
  • Duration per spasm: 0.5-2 seconds (intermediate between myoclonic and tonic seizures)
(Bradley and Daroff's Neurology in Clinical Practice)

West Syndrome (the classic cluster seizure syndrome)

  • Peak onset: 3-7 months of age
  • Clinical triad:
    1. Epileptic spasms (occurring in clusters, sometimes multiple times/day)
    2. Arrest/deterioration of psychomotor development
    3. Hypsarrhythmia on EEG (high-voltage disorganized activity, slow waves, multifocal spikes, with periods of attenuation)
  • ~2/3 of infants have underlying brain lesions
  • 70% develop intellectual disability
  • Treatment: ACTH / corticosteroids (especially without known underlying pathology)
(Bradley and Daroff's Neurology in Clinical Practice)

Summary Table

QuestionAnswer
Most common epileptic focus in adultsTemporal lobe (mesial/mediobasal)
Most common pathology at that focusMesial temporal sclerosis
Seizure type that classically occurs in clustersEpileptic spasms (infantile spasms)
Syndrome where cluster seizures are hallmarkWest Syndrome
Age of onset for West Syndrome3-7 months (peak)
This is a shared conversation. Sign in to Orris to start your own chat.