Status epilepticus is a medical emergency defined as seizure activity that lasts >30 minutes, or multiple seizures without recovery >30 minute. In practice, seizures lasting >5 minutes are treated as status as most seizures will terminate within 1-2 minutes.
Pathophysiology
- Animal studies have found an increase in cerebral blood flow, heart rate and blood pressure in the initial stages of status.
- As the seizures continue, blood pressure, glycaemia, and cerebral oxygenation begin to decrease.
- Normally, seizures will self-terminate through a host of proposed mechanisms including depletion of neurotransmitters and ATP.
- In status epilepticus, it is thought changes in GABA-A, NMDA, and AMPA receptor expression result in reduced inhibition, and increased neuronal excitability.
- The earlier benzodiazepines are administered to terminate status epilepticus, the more likely they are to be successful at terminating a seizure. With time, they lose their potency.
- GABA-A is one of the major inhibitory neurotransmitters in the CNS. It is thought that with prolonged seizure activity, GABA-A receptors are internalised and also have reduced density at the synapse. This is thought to be one of the reasons there is reduced response to benzodiazepines with prolonged seizure activity.
- Thus, although benzodiazepines are used as first-line, alternative drugs are used if there is no response to benzodiazepines.
- Neuropathological studies have shown brain injury and neuronal death in some cases of status epilepticus – it is unclear what the specific cause of this is i.e. if it’s due to cerebral hypoxia or other contributing factures such as hypoglycaemia, acidosis, and hyperthermia, but ultimately prolonged seizures have been shown to result in brain injury in some cases.
Causes
- Sub-optimal management of epilepsy
- Hypoglycaemia
- Eclampsia
- Alcohol withdrawal
- Stroke
A-E Assessment
- Airway:
- Secure the airway – the tongue can cause obstruction so airway manoeuvres/airway adjuncts may be necessary
- Suction secretions
- Breathing:
- High flow oxygen is usually administered
- Monitor oxygen saturations
- Circulation:
- HR and BP
- Bloods: FBC, U&E, LFT, Bone Profile (for calcium), anti-epileptic drug levels
- IV access if not already present
- ABG: For oxygenation and lactate – lactate will be raised in case of seizure due to increased anaerobic metabolism. There may also be an acidosis on the gas as a consequence.
- Disability:
- Pupil reaction
- Temperature: There can sometimes be a hyperthermia due to repetitive muscle contraction.
- Blood glucose: Extremely important and should not be forgotten in seizures as hypoglycaemia may be the underlying cause.
- Else:
Management
First-Line Treatment
Benzodiazepines: Work by enhancing the effects of GABA
- Community:
- Buccal midazolam: 10mg (can also be given IM)
- Rectal diazepam: 10-20mg
- IV access + resuscitation facilities available:
- IV lorazepam 0.1mg/kg but usually a 4mg bolus is given.
- Repeat the dose if the seizure hasn’t stopped with 5-10 minutes of the first dose.
Second-Line Treatment
- Levetiracetam
- Phenytoin
- Sodium valproate
One of the above can be attempted. Levetiracetam is commonly used as it’s quick to give and has less side effects than the alternatives. If there is no response to a second-line drug, an alternative second-line can be tried.
Third-Line Treatment
- Phenobarbital
- General anaesthesia
References
https://www.nice.org.uk/guidance/ng217/chapter/7-Treating-status-epilepticus-repeated-or-cluster-seizures-and-prolonged-seizures#status-epilepticus
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6506391/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6293062/
https://www.epilepsy.va.gov/EPILEPSY/Library/11-2-11_article_1.pdf
