Seizure & Epilepsy Part 2

Seizure & Epilepsy Part 2

• Epilepsy syndromes include seizure types, etiology (idiopathic or symptomatic), age of onset, prognosis, and response to treatment
• Classifying syndromes is important as different parts may respond similarly to treatment and have similar prognoses
• Juvenile myoclonic epilepsy is a common idiopathic generalised epilepsy syndrome
• It is inherited, age of onset is adolescence, and characterised by myoclonic jerks, often occurring after awakening. Absence seizures and sleep-deprivation or alcohol can sometimes precipitate seizures
• Intelligence is not significantly affected
• EEG characteristics include bursts of fast generalised polyspike and wave activity
• Not progressive, but needs life-long therapy. It responds well to Valproic Acid and Lamotrigine.

Lennox‐Gastaut Syndrome

• A severe symptomatic generalised epilepsy syndrome
• It's characterized by (1) multiple seizure types, (2) characteristic EEG, and (3) diffuse cognitive dysfunction.

Age of Onset (1-7 years)

• Seizures are typically generalised, including atonic (falling), tonic, tonic-clonic, and atypical absence seizures.
• Intellectual impairment is common
• Etiology or cause of Lennox‐Gastaut Syndrome is usually symptomatic / secondary (e.g., prematurity, perinatal injury, metabolic disease of infancy)

Management and Prognosis

• Lennox-Gastaut Syndrome has a very poor prognosis.
• Treatment is very difficult and often requires multiple drug regimens.

EEG (Electroencephalogram)

• EEG records electrical activity of the brain via scalp electrodes
• Electrodes are placed on the scalp in standard positions
• Potential differences are recorded
• Normal background EEG activity is 8-12 Hz (alpha rhythm)
• Epilepsy-epileptiform activity is characterized by sharp or spike-and-wave patterns, distinct from background activity
• Activation procedures, like hyperventilation, photic stimulation, and sleep deprivation, can induce or reveal underlying abnormalities

Uses of EEG in Epilepsy

• Supports the diagnosis of epilepsy
• Classifies seizures
• Localises seizure focus before surgery
• May assist in prognosis
• Tracks status epilepticus management

EEG in Epilepsy Diagnosis

• Useful during an actual seizure to electrographically confirm if seizures are happening
• Most EEG recordings are done interictally (between seizures)
• Interictally, EEGs are often normal
• Abnormal EEG in an epileptic patient is present in around 55% of cases
• Repeated recordings and activation procedures can raise the positive yield to approximate 80%

What to Look For (EEG)

• Epileptiform activity: bursts (paroxysms) of spikes and sharp wave activity, which is distinct from background activity
• Episodes clinically suggestive of seizures: Epileptiform activity can help with epilepsy diagnosis
• Even with a normal EEG, do not rule out epilepsy; clinical history is crucial.

Classifying Seizures and Epilepsy

• Some epilepsy syndromes have characteristic EEGs
• EEG can differentiate between complex partial seizures and absence seizures

Status Epilepticus

• Definition: continuous seizures or recurrent seizures without recovery of consciousness in between, lasting a duration of at least 30 minutes
• Any seizure type can progress to status epilepticus
• Status epilepticus represents an emergency with high morbidity and mortality

Complications of Status Epilepticus (in initial 30 minutes)

• Catecholamine increase: Heart rate and blood pressure increase
• Elevated temperature
• Metabolic acidosis
• Raised white blood cell count
• Mild lowered oxygen (pO2) and increased carbon dioxide (pCO2) levels
• Other complications: Fractures, rhabdomyolysis, glucose increases, aspiration, and renal failure

After 30 Minutes of Status Epilepticus

• Systemic changes: blood pressure will decrease, respiratory compromise occurs, acidosis intensifies, and glucose levels fall
• Prolonged electrical activity itself leads to neuronal damage
• Focal impairment of awareness and absence seizures are associated with status epilepticus, among other symptoms