Seizure Disorder

Definitions

• Seizure: clinical manifestations of an abnormal, uncontrolled activity by a group of neurons– Unprovoked (idiopathic)– Provoked (acute symptomatic)

• Seizure disorder: condition with recurrent, paroxysmal seizures without evidence of a reversible metabolic cause

Definitions

• Tonic – A sustained muscular contraction

• Clonic – Intermittent muscular contractions and relaxations

• Aura: subjective disturbance of perception representing a focal electrical disturbance

Pathophysiology

• A seizure is a temporary involuntary disturbance of brain function that may be manifested as impaired consciousness, abnormal motor activity, sensory disturbances or autonomic dysfunction.

Pathophysiology• Seizures are accompanied by abnormal electrical

discharges in the brain that can usually be detected by electroencephalography (EEG).

• Caused by an increase in cell excitability of neurons.

• Maybe caused by a deficiency in an inhibitory neurotransmitter eg. GABA

Signs and Symptoms

• One or a combination– Motor symptoms– Sensory symptoms– Autonomic symptoms

Signs and Symptoms

• Motor cortex: cause movements on contralateral side according to the somatotopic location of the seizure focus.

• Somatosensory cortex: cause an epileptic aura in which a sensation is experienced. Also depends on somatotopic representation

Signs and Symptoms

• Auditory cortex: cause an auditory aura (humming, buzzing, and ringing).

• Visual cortex: cause a visual aura (flashes, colours).

Classification

• Of all patients with epilepsy, 70% have only one type of seizure disorder whereas the remaining 30% have two or more types.

Staging of Seizures

1. Aura– The first self-experienced symptom

2. The Attack

3. Post-Ictal Period– Associated with headache, drowsiness, or

focal neurologic abnormalities– May last for hours or days

Classification

• Partial seizures

• Generalized seizures

Partial Seizures

• Focal origin

• Types:– Simple partial– Complex partial– Secondarily generalized partial

EEG: Partial Seizures

Generalized Seizures

• Virtually simultaneous onset in both hemispheres

• Diverse clinical manifestations

• Loss of consciousness

ClassificationClassification

All SeizuresAll Seizures

GeneralizedGeneralized Partial Partial

Absence Tonic-Clonic Simple ComplexAbsence Tonic-Clonic Simple Complex

Also Atonic & Myoclonic

Secondarily generalized partial

EEG: Generalized Seizures

Generalized Seizures

• 4 categories:– Absence (petit mal)– Atonic– Myoclonic– Tonic-clonic (grand mal)

Absence Seizures

• (Petit mal seizures)

• Generalised non-convulsive epileptic events

• Eg. Blank stare, motionless, unresponsive

• May have assoicated automated movements eg. Lip smacking, grimacing

Atonic Seizures

• (Drop attacks)

• Sudden loss of muscle tone leading to slackening of the jaw, drooping of the limbs or falling to the ground

Myoclonic Seizures

• Brief involuntary Muscle contractions

• Bilateral jerking of muscles (generalised or localised)

Tonic-clonic Seizures

• (Grand mal seizures)

• Major motor seizure

• Tonic-clonic contraction of muscles with loss of consiousness

• Cyanosis may occur due to contraction of respiratory muscles

• Normally lasts 60 - 90 s

Diagnosis

• History

• Examination

• “Routine laboratory tests”

• EEG

• Neuroimaging (CT/MRI)

• Differential Diagnosis