The extracranial effects of convulsive status epilepticus

A prolonged uncontrollable seizure is not a consequence-free experience. There is typically a price to pay for such vigorous exercise. A good article, unfortunately trapped behind a paywall, is available to explain the systemic effects of ongoing convulsive seizures. In short, most of the physiological changes can be associated with an excess of sympathetic stimulation, and a massive increase in the body’s metabolic demand.

Respiratory effects of ongoing convulsive seizures

  •  There is likely to be hypoxia. This can be due to aspiration (which is common) or purely due to hypoventilation (due to incoordination of respiratory muscles).
  • There is likely to be hypercapnea, for the same reasons. Additonally, the huge bulk of vigorously contracting muscles is metabolizing a lot more substrate, and thus the net amount of CO2 production is greater.

Cardiovascular effects of ongoing convulsive seizures

  • There is hypertension initially, due to a massive sympathetic release of catecholamines. During this stage cerebral blood flow is also increased. The hypertension can be so severe that neurogenic pulmonary oedema may develop.
  • This sympathetic storm can also induce cardiac arrhythmias.
  • Thereafter, a hypotensive period ensues, when cardiac output is decreased, and the patient is relatively vasodilated.

Acid-base effects of ongoing convulsive seizures

  • Naturally, lactic acidosis is the consequence of sustained muscle contraction.
  • Respiratory acidosis is also observed.

Changes in CS biochemistry

Can one tell that a seizure is occurring simply be analysisng the CSF? Some say that yes, you can. Pleocytosis (that is to say, an elevated WCC in the CSF) is seen in around 60% of patients with status epilepticus, although the author of the linked article cautions that "The most important influence on the CSF WBC count is the underlying cause of the SE".

Changes in intracranial pressure

Owing to the increased intracranial blood flow, there is a period of hyperaemia, and during this period a patient with an ICP monitor will register a sharp increase in ICP.


Like any vigorous exercise, seizures can result in the breakdown of individual myocytes, and the myocyte content thus enters the bloodstream. There are case reports of clinically significant rhabdomyolysis following status epilepticus, but more often the elevation of CK is merely a footnote and there is no renal involvement.



Oh's Intensive Care manual:

Chapter 49   (pp. 549) Disorders  of  consciousness  by Balasubramanian  Venkatesh

Chapter   50   (pp. 560) Status  epilepticus  by Helen  I  Opdam

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