Seizures 

1. Definition 

A seizure is a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

An epileptic seizure ≠ epilepsy.

Epilepsy (ILAE definition)

Epilepsy is diagnosed if:

1. ≥2 unprovoked seizures >24 hrs apart
   OR
2. 1 unprovoked seizure with ≥60% recurrence risk over 10 years
   OR
3. Diagnosis of an epilepsy syndrome

2. Classification of Seizures (ILAE 2017)

Classification is clinical + EEG-based, 

A. Focal Onset Seizures (originating in one hemisphere)

1️⃣ Focal aware seizure (previously simple partial)

• Awareness preserved
• Motor / sensory / autonomic / psychic symptoms
• Eg:
• Motor jerking of one limb
• Déjà vu (temporal lobe)
• Epigastric rising sensation

2️⃣ Focal impaired awareness (previously complex partial)

• Altered awareness
• Automatisms (lip-smacking, picking)
• Post-ictal confusion

3️⃣ Focal to bilateral tonic-clonic

• Starts focal → generalises

B. Generalized Onset Seizures (bilateral networks from onset)

1️⃣ Absence seizure

• Brief staring (5–15 sec)
• No postictal phase
• Hyperventilation provokes
• EEG: 3 Hz spike-wave
• Childhood absence epilepsy

2️⃣ Tonic-clonic

• Tonic phase (stiffening) → clonic jerking
• Postictal confusion
• Tongue biting (lateral), incontinence

3️⃣ Myoclonic

• Sudden brief jerks
• Seen in Juvenile Myoclonic Epilepsy (JME)

4️⃣ Atonic

• Sudden loss of tone (drop attacks)

5️⃣ Tonic / Clonic alone (less common)

C. Unknown Onset

If onset not witnessed.

3. Pathophysiology

Seizures result from:

• Imbalance between excitatory (glutamate) and inhibitory (GABA) transmission
• Increased neuronal synchronisation
• Ion channel dysfunction

Mechanisms:

• Sodium channel mutation
• GABA receptor dysfunction
• NMDA receptor overactivation
• Structural lesions (tumour, scar, stroke)

4. Causes of Seizures 

A. Acute symptomatic seizures

• Hypoglycaemia
• Hyponatraemia
• Hypocalcaemia
• Uraemia
• Alcohol withdrawal
• CNS infection
• Head trauma

B. Structural

• Tumour
• Stroke
• AVM
• Mesial temporal sclerosis

C. Genetic epilepsy syndromes

• JME
• Childhood absence epilepsy

D. Autoimmune

• Anti-NMDA receptor encephalitis
• LGI1 encephalitis

E. Functional (non-epileptic attack disorder)

5. First Seizure in Adults 

History

• Witness account crucial
• Aura?
• Tongue bite? (lateral = epilepsy)
• Postictal confusion?
• Triggers?
• Alcohol/drugs?

Examination

• Focal neuro deficit
• Signs of meningitis
• Papilloedema

Red flags

• Persistent focal deficit
• Immunosuppression
• Head injury
• Cancer history

6. Differentials 

Other differentials:

• Psychogenic non-epileptic seizures
• Migraine
• TIA
• Hypoglycaemia

7. Investigations

1️⃣ Blood tests

• Glucose (urgent)
• U&E (Na+)
• Ca2+, Mg2+
• LFT
• Toxicology if indicated

2️⃣ EEG

• Helps classification
• Not required acutely unless status suspected

3️⃣ MRI brain (preferred)

Indications:

• First unprovoked seizure(A first episode of epileptic seizure that occurs without an immediate identifiable precipitating cause.)
• Focal features
• Abnormal exam

4️⃣ CT head

• Acute presentation
• Trauma
• Suspected bleed

8. Antiepileptic Drugs 

9. Driving Advice (UK)

After first unprovoked seizure:

• No driving for 6 months (Group 1)

Established epilepsy:

• 1 year seizure free required