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Status epilepticus

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Definition

  • continuous seizure activity lasting >30 mins
    • has been suggested that the duration be reduced to 5 mins on the basis that typical fits rarely last 5 mins and that spontaneous termination is less likely in fits lasting >5 mins. In children spontaneously remitting fits may last longer - up to 12 mins
  • two or more seizures with recovery of baseline consciousness

Types

  • Repeated generalized tonic and/or clonic convulsive seizures where the patient does not fully recover neurological function between attacks
  • Non-convulsive status: prolonged “twilight” state
  • Continuous focal epileptic activity without alteration of consciousness

Aetiology

Patients without past history of epilepsy Patients with past history of epilepsy
  • cerebral tumour

  • stroke

  • intracranial infection

  • hypoxic encephalopathy

  • drug abuse and overdose

  • electrolyte disturbance

  • hypoglycaemia

  • HIV infection

  • first presentation of primary epilepsy (by exclusion)

  • poor compliance

  • change in antiepileptic drug dosage or type

  • alcohol withdrawal

  • pseudostatus

 

Generalized convulsive status epilepticus

  • Most common and dangerous form of SE

  • Wide range of presentations from repeated overt generalized seizures to very subtle focal twitches of a localized part of the bocy

  • If patient inadequately treated generalized convulsions may stop despite continued ictal EEG discharges

  • Pseudoseizures are most important differential

    • Can only be distinguished with complete certainty with EEG monitoring. Suggestive clinical features:

      • more common in females

      • history of psychosocial disturbance

      • consciousness may be retained in presence of bilateral jerking

      • resistance to examination

      • vocalisation

      • pelvic thrusting

      • gaze aversion

      • normal pupillary response during convulsion

      • normal tendon and plantar responses immediately after fit

Complications

  • Hypoxia

  • Lactic acidosis

  • Hypercarbia

  • Rhabdomyolysis, hyperkalaemia, ARF

  • Hyperpyrexia

  • Hypoglycaemia

  • Hyper/hypotension

    • initial hypertension, subsequent hypotension

  • Cardiac arrhythmias

  • Pulmonary oedema

  • Aspiration pneumonitis

  • Intracranial hypertension

Investigations

Initial Subsequent
  • Glucose, urea, creatinine, sodium, potassium, calcium

  • Anti-convulsant levels

  • Complete blood count

  • Arterial blood gases or oximetry

  • Urinalysis

  • Liver function tests

  • Magnesium

  • Toxicology screen

  • CT brain

  • ± Lumbar puncture (not within 30 mins of fit)

  • EEG

 

Treatment

  • If hypoglycaemic or blood glucose unknown give glucose

    • adults: 50ml of 50% glucose preceded by 100mg thiamine

    • children: 2ml/kg of 25% glucose

  • first line agent of choice is lorazepam. Not only is it more effective than diazepam but its longer duration of anti-epileptic action (>6 h compared with 20 mins) means that recurrence of fits is less likely

    • if diazepam is given it should be followed immediately by a loading dose of phenytoin without waiting for a further fit

  • if first line therapy is ineffective the probability of either phenytoin or phenobarbitone terminating the status epilepticus is not high and therefore some authorities recommend treating these patients for refractory status epilepticus. Others recommend trying phenytoin (if this has not already been done) before deciding the patient has refractory SE

Refractory status epilepticus

  • intubate the patient
    • if the patient is hyperkalaemic or the potassium is unknown use rocuronium instead of suxamethonium as muscle relaxant. Disadvantage of rocuronium is that seizures are masked for a prolonged period of time.
  • treatment options for refractory SE are:

    • midazolam infusion

      • 0.2 mg/kg loading followed by an infusion of 0.1-2 mg/kg/h

      • main disadvantage is tachyphylaxis with may necessitate a significant dose increase after 24-48h

    • propofol infusion

      • 3-5 mg/kg loading followed by 30-100 µg/kg/min

      • main disadvantage is risk of propofol infusion syndrome:

        • severe metabolic acidosis

        • rhabdomyolysis

        • cardiovascular collapse

    • thiopentone infusion

      • 3-5 mg/kg loading followed by 3-5 mg/kg/h

      • main disadvantage is prolonged sedation due to long elimination half life

  • treatment should be titrated to abolish electrical seizure activity rather than a specific EEG pattern. Seizures may still occur despite burst-suppression and may be abolished when EEG only shows slow waves.

Non convulsive status epilepticus

  • Incidence in comatose patients in ICU varies in incidence from 8% of medical ICU patients to 30-40% of patients in neuro-intensive care units. Occurs in significant proportion of patients with another cause for coma eg subarachnoid haemorrhage, traumatic brain injury
  • Two types:
    • Absence SE
      • Prolonged confusional state

      • Characteristic EEG pattern

      • Almost never causes coma

      • Patients rarely require ICU admission

    • Complex partial SE
      • Diagnosis may be difficult

      • Variable presentation

      • Characteristic manifestation is altered mentation with variable responsiveness and amnesia

      • May demonstrate automatism, complex motor activity, bizarre behaviour, lateralizing or localizing neurological deficits (eg aphasia or paresis)

      • Duration usually minutes to hours

Further reading

Alldredge BK et al. A comparison of lorazepam, diazepam, and placebo for the treatment of out-of-hospital status epilepticus. N Engl J Med 2001; 345:631-7

Marik PE and Varon J. The management of status epilepticus. Chest 2004; 126:582-591

Treiman DM et al. A comparison of four treatments for generalized convulsive status epilepticus. N Engl J Med 1998; 339:792-8


©Charles Gomersall, February, 2015 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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