7.3 Seizures, Status Epilepticus & Epilepsy Management

Seizures, Status Epilepticus & Epilepsy Management

Epilepsy is defined by the International League Against Epilepsy (ILAE) as a disease characterized by an enduring predisposition to generate epileptic seizures, typically diagnosed after two unprovoked seizures occurring >24 hours apart, or one unprovoked seizure with an estimated recurrence risk >60% over 10 years.

---

Seizure Classification & Clinical Semiologies

Seizures are divided fundamentally based on their onset into focal (originating within networks limited to one cerebral hemisphere) and generalised (originating at some point within and rapidly engaging bilaterally distributed networks).

1. Focal Seizures

• Focal Aware Seizures (Simple Partial): Consciousness remains entirely intact throughout the episode; subjective aura or motor/sensory focal activity experienced.
• Focal Impaired Awareness Seizures (Complex Partial): Consciousness or awareness is altered or impaired at any point during the attack; patients cannot respond normally and exhibit post-ictal amnesia.
• Anatomical Lobar Localization:
  • Temporal Lobe Seizures (the most common focal epilepsy in adults): Often caused by hippocampal sclerosis. Present with rising epigastric aura ('butterflies in stomach'), affective disturbances (sudden intense fear, euphoria, déjà vu / jamais vu), olfactory/gustatory hallucinations (smelling burnt rubber), and prominent motor automatisms (involuntary lip-smacking, chewing, repetitive swallowing, or purposeless hand fumbling). Characterised by prolonged post-ictal confusion and amnesia.
  • Frontal Lobe Seizures: Typically brief (<30–60 seconds), frequent, occurring predominantly during sleep. Characterized by prominent motor manifestations: asymmetric tonic posturing, 'fencing posture', head and eye deviation away from the epileptogenic focus (adversive), violent bipedal kicking or pelvic thrusting (hypermotor automatisms), or the Jacksonian March (clonic jerking marching sequentially from the distal fingers up the arm to the face).
  • Parietal Lobe Seizures: Sensory phenomena including contralateral tingling, numbness, dysaesthesias, or distorted body schema illusions.
  • Occipital Lobe Seizures: Elementary visual phenomena such as flashing lights, brightly coloured geometric shapes, transient scotomas, or oculomotor nystagmus.

2. Generalised Seizures

• Generalised Tonic-Clonic Seizures (GTC):
  • Tonic Phase (10–20 sec): Sudden loss of consciousness, sustained generalised muscle contraction, ictal cry (forced air expulsion across contracting vocal cords), respiratory arrest with cyanosis, and tongue biting (characteristically along the lateral border of the tongue).
  • Clonic Phase (30–90 sec): Synchronous rhythmic, violent jerking of all four limbs, hypersalivation, urinary/faecal incontinence, and autonomic activation (tachycardia, diaphoresis).
  • Post-ictal Phase: Flaccid coma gradually transitioning to deep sleep, confusion, headache, generalized myalgias, and transient Todd's paresis.
• Absence Seizures (Typical Petit Mal):
  • Exclusively onset in childhood (ages 4–10 years). Characterised by brief (5–15 seconds) sudden cessation of activity and vacant staring, with immediate resumption of pre-ictal activity without any post-ictal confusion.
  • Provoked reproducibly in clinic by hyperventilation for 3 minutes.
  • Electroencephalogram (EEG) demonstrates pathognomonic synchronous 3 Hz spike-and-wave discharges across all leads.
• Myoclonic Seizures:
  • Brief, shock-like involuntary muscle twitches without impairment of consciousness.
  • Hall-mark of Juvenile Myoclonic Epilepsy (JME): adolescent onset presenting with sudden morning myoclonic jerks (e.g. dropping a cup of tea or toothbrush), provoked by sleep deprivation and alcohol intake, with generalized spike-and-wave discharges on EEG.
• Atonic ('Drop Attacks') & Tonic Seizures: Sudden loss of postural tone causing catastrophic falls, commonly seen in severe childhood epileptic encephalopathies (such as Lennox-Gastaut syndrome).

---

Emergency Management of Convulsive Status Epilepticus

Convulsive status epilepticus is defined by the ILAE as a continuous convulsive seizure lasting ≥5 minutes (Time t1), or two or more discrete seizures between which the patient does not fully regain consciousness. Time t2 is defined as 30 minutes, beyond which severe neuronal damage, pharmacoresistance, and systemic decompensation ensue.

Step 1: Immediate Triage & Resuscitation (0–5 Minutes)

• Apply ABCDE framework: secure airway, position in lateral recovery position, administer high-flow 100% oxygen (15 L/min via non-rebreather mask), attach pulse oximetry, ECG, and blood pressure monitors.
• Secure wide-bore intravenous access and take bloods (electrolytes, calcium, magnesium, renal and liver function, FBC, anticonvulsant drug levels, venous blood gas).
• Check capillary blood glucose immediately: If blood glucose is <4.0 mmol/L, administer 100 mL of 10% or 20% glucose IV. In patients with suspected alcohol misuse or malnutrition, administer intravenous Pabrinex (thiamine) before or concurrently with glucose to avoid precipitating acute Wernicke's encephalopathy.

Step 2: Early Status Epilepticus (5–10 Minutes) — First-Line Benzodiazepines

• If IV Access Available: Administer Intravenous Lorazepam 4 mg (0.1 mg/kg in children) as a slow IV bolus over 2 minutes.
• If IV Access Unavailable / Pre-hospital: Administer Buccal Midazolam 10 mg (instilled between gums and cheek) OR Rectal Diazepam 10 mg.
• Failure to Terminate at 10 Minutes: If convulsive seizure activity persists 5–10 minutes after the first dose, administer a single repeat dose of the same benzodiazepine (e.g. repeat IV Lorazepam 4 mg).
• Strict Rule: Administer a maximum of two benzodiazepine doses in total to minimize the risk of profound respiratory depression and hypotension.

Step 3: Established Status Epilepticus (20–40 Minutes) — Second-Line IV Anti-Seizure Medications

If convulsions persist despite two adequate doses of benzodiazepines, immediately commence a second-line non-sedating IV anti-seizure medication infused over 10–15 minutes:

• Intravenous Levetiracetam (First Choice in many UK centres): Dose 60 mg/kg (maximum dose 4500 mg) infused over 10 minutes. Preferred due to rapid infusion time, superior cardiac safety, and minimal drug interactions.
• Intravenous Sodium Valproate: Dose 40 mg/kg (maximum dose 3000 mg) infused over 5–10 minutes.
• Intravenous Phenytoin: Dose 20 mg/kg infused over 20–30 minutes.
  • Mandatory Phenytoin Precautions: Infusion rate must never exceed 50 mg/minute in adults.
  • Continuous ECG and blood pressure monitoring are mandatory during infusion due to the high risk of severe hypotension, heart block, and fatal cardiac arrhythmias.
  • Must only be mixed with 0.9% normal saline (precipitates in glucose solutions).
  • Extravasation causes severe skin necrosis and limb ischaemia ('purple glove syndrome').

Step 4: Refractory Status Epilepticus (>40–60 Minutes)

• Convulsions continuing despite adequate first-line benzodiazepine and second-line IV anti-seizure therapy constitute refractory status epilepticus.
• Immediate ICU Transfer: Patient must be urgently transferred to the Intensive Care Unit for endotracheal intubation, mechanical ventilation, invasive arterial line monitoring, and continuous EEG monitoring.
• General Anaesthesia: Initiate titratable continuous IV anaesthetic infusions: Propofol, Midazolam, or Thiopental sodium titrated to achieve burst suppression on continuous EEG for 12–24 hours.

---

Long-Term Anti-Seizure Medication (ASM) Selection

Current NICE guidelines emphasize monotherapy tailored to seizure semiology, patient sex, age, and comorbidity profile.