Seizures

Question 1

How long do most seizures last? Do they usually need treatment?

Answer 1

Most seizures are brief and end within 1-3 minutes without drug treatment. Most seizures are brief and do NOT require drug treatment.

Question 2

What are acute symptomatic seizures?

What is epilepsy?

Answer 2

Acute symptomatic seizures - seizures caused by a transient systemic or central nervous system

Epilepsy - disorder characterised by a tendency to experience recurrent seizures

Question 3

What is status epilepticus? At what time point do you usually start treatment? What are the two different kinds of SE?

Answer 3

Continuous seizure activity or, repeated seizures without full recovery of consciousness between attacks - Minimum duration required for diagnosis is 30 minutes - However, drug treatment should start after 5 minutes of continuous seizure activity Can be convulsive vs. non-convulsive status epilepticus

Question 4

Describe the motor activity of convulsive status epilepticus

What usually happens after 30-45min of untreated seizures?

What may be the only means of diagnosis after this time point?

What happens to the motor activity after treatment?

If a patient stops having seizures but remains comatosed, what investigation should you order?

Answer 4

Seizures of convulsive status epilepticus are usually tonic-clonic, but may be tonic, and after treatment may become clinically subtle. Furthermore, after 30-45min of uninterrupted seizures, the signs may become increasingly subtle eg, only mild clonic movements of only the fingers or fine, rapid movements of the eyes, paroxysmal tachycardia/hypertension/pupillary dilatation. In such cases, EEG may be the only method of establishing the diagnosis. Thus if a patient stops having overt seizures, yet remains comatose, an EEG should be performed to rule out ongoing SE.

Question 5

Non-convulsive status epilepticus (NCSE) - describe the different kinds of NCSE. How urgent is treatment for NCSE?

Answer 5

NCSE may be generalised (absence SE) or focal [partial] (impaired awareness [complex partial] or aware [simple partial] status epilepticus). Words in [] are from old seizure classification system. Treatment for NCSE is less urgent and the risks of therapy, particularly respiratory depression, must be weighed against the risks of continuing non-convulsive seizures. This is because the ongoing seizures are not accompanied by the severe metabolic disturbances seen with GCSE - however, evidence suggests that NCSE can cause cellular injury in the region of the seizure focus; therefore should be treated as prompty as possible but not as urgent as generalised convulsive SE. Good analogy: convulsive SE is analogous to VF, NCSE is analogous to AF with or without rapid ventricular response in that management varies with symptom severity.

Question 6

What are some causes of acute symptomatic seizures?

What will happen to the seizure if you treat the underlying cause?

Answer 6

If underlying cause is known, treat underlying cause - usually stops the seizure. Seizures will recur if the cause recurs eg, during benzodiazepine withdrawal, or if the acute illness has caused permanent brain injury eg, gliosis caused by herpes encephalitis.

Question 7

Describe the acute management of seizures

Answer 7

Acute management of seizures

• Most are brief 1-3minutes, and do not require drug treatment
• DRSABCDE
  
  • Supportive care - position to L) lateral position to protect the airway
  • Vitals
  • BSL
  • IV access
  • Bloods - FBE, UEC, CMP, LFTs, anti-epileptic drug concentration, VBG
    
    • VBG gives the fastest indication of patient’s acid-base status, ventilation, concentrations of sodium, glucose, and haemoglobin
• If alcohol withdrawal cannot be excluded, give IV thiamine:
  
  • IV thiamine 200-500mg TDS for 5-7 days.
  • Then 100mg IV/IM daily for 1-2 weeks OR 100mg PO TDS for 1-2 weeks
  • Then 100mg PO daily thereafter
• If continuous seizure activity >5min OR when patient has repeated seizures without full recovery of consciousness between attacks, treat as for status epilepticus:
  
  • Give benzodiazepine
    
    • Midazolam 10mg IV over 2min
    • Diazepam 10mg IV over 2min
    • Clonazepam 1mg IV over 2min
    • If no IV access:
      
      • Midazolam 10mg IM (if >40kg) 5mg IM (if <40kg)
      • Midazolam 10mg bucally or intranasally
      • Midazolam solution for injection (hydrochloride salt) can be given bucally or intranasally
    • Side note: for eclamptic seizures, magnesium sulfate is the drug of choice
  • Give AED
    
    • If the seizure stops promptly and the cause has been identified and reversed, further AEDs are not needed.
    • In all other patients, prevent further acute seizures by starting an AED as benzodiazepines have short anticonvulsant effects.
      
      • Phenytoin sodium 20mg/kg IV - no faster than 50mg/minute (25mg/minute in elderly patients or co-morbid patients). Monitor blood pressure and ECG. Phenytoin has more adverse effects than sodium valproate (arrhythmias such as acute bradycardia, hypotension, infusion related adverse effects such as skin necrosis ‘purple glove syndrome’ in drug extravasationetc).
        
        • Caution: if seizure is due to overdose with a cardiotoxic drug eg, tricyclic antidepressant), use phenytoin with caution.
      • Sodium valproate 40mg/kg (max 3000mg) IV over 5-10 minutes
    • In adults, lacosamide and levetiracetam can be used to treat status epilepticus, but supporting evidence is limited. Phenobarbitone can also be used, though ideally it should be given in an intensive care setting due to the risk of respiratory depression when given after a benzodiazepine
  • When visible signs of seizure activity has stopped, perform an EEG in all patients who have not fully regained consciousness to exclude NCSE.
  • Consider transfer to ICU
    
    • If seizure activity continues (refractory status epilepticus), transfer patient to ICU, continuous EEG monitoring.
    • Deciding when to escalate therapy to an anaesthetic drug with artificial ventilation depends on several clinical factors and the skill set of available personnel. Ongoing seizures with airway or respiratory compromise should prompt early escalation, to minimise the risk of injury to the central nervous system. As a general guide, an infusion of a general anaesthetic (eg thiopentone, propofol) should be started in patients who are still having seizures after 15 minutes, despite treatment with a benzodiazepine and an antiepileptic drug. Evidence to guide the choice of drug is lacking. When patients are ventilated, avoid long-acting neuromuscular blocking drugs if possible, because these can mask ongoing seizures.
• Check for and manage for complications of seizures
  
  • Complications of acute seizures
    
    • Aspiration
    • Trauma eg, posterior shoulder dislocation
  • Complications of prolonged seizures
    
    • Generalised convulsive status epilepticus is a medical emergency and must be treated immediately due to complications of:
      
      • Cardiorespiratory dysfunction Eg, non-cardiogenic neurogenic pulmonary oedema - as per UpToDate, due to sympathetic overactivity, massive catecholamine surges, blood shifting from systemic to pulmonary circulation, secondary elevation of left atrial and pulmonary capillary pressures. Pulmonary capillary leak/permeability may play a role via mechanical injury and/or direct nervous system control over capillary permability
    • Hyperthermia
    • Rhabdomyolysis, acidosis, kidney failure
    • Metabolic derangements
    • Irreversible CNS injury due to above. CNS injury can occur even when a patient is paralysed with neuromuscular blockade but continues to have seizures on EEG
• Immediate follow-up after a seizure
  
  • If no history of seizures: Hx/Ex, BSL, full set of bloods, urine drug screen, CT-B, consider LP if intracranial infection suspected
  • If history of previous seizures but not being treated with AED: as above, AED usually required
  • If history of previous seizures and on AED: explore common triggers for seizures (Eg, sleep deprivation, febrile illness, EtOH, non-compliance with AEDs), measure plasma concentration of drugs