Status epilepticus from Harrison's Practice

Status Epilepticus
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Definition
A state of continuous seizures or repetitive, discrete seizures with impaired consciousness in the interictal period
Duration
Traditional criterion: 15–30 minutes
Practical criterion: duration prompting acute use of anticonvulsant therapy; typically > 5 minutes
May occur with all type of seizures: grand mal (tonic-clonic) status, myoclonic status, petit mal status, and temporal lobe (complex partial) status
Associated with major cerebral and systemic physiologic changes
Initial stage (first 30–60 minutes)
Cerebral metabolism is greatly increased because of seizure activity, but physiologic mechanisms are sufficient to meet the metabolic demands.
Cerebral: increased blood flow, increased metabolism
Autonomic and cardiovascular: hypertension, increased cardiac output, massive catecholamine release, tachycardia, arrhythmias, hyperpyrexia
Metabolic: lactic acidosis, hyperglycemia
Decompensated phase
Cerebral metabolic demands cannot be fully met, resulting in hypoxia and altered cerebral and systemic metabolic patterns.
Cerebral: hypoxia, hypoglycemia, increased intracranial pressure
Autonomic and cardiovascular: hypoxia, hypotension, hyperpyrexia
Metabolic: hypoglycemia, hyponatremia, hyperkalemia, metabolic acidosis
Generalized status is life threatening when accompanied by hyperpyrexia, acidosis (from prolonged muscle activity), and respiratory or cardiovascular compromise.

Epidemiology
Incidence in the U.S.
18–50 cases per 100,000 annually
Half are secondary to acute central nervous system (CNS) insult.
One-third are unprovoked first seizure.
One-sixth are in patients with known epilepsy.
Noncompliance with medications is primary risk factor in patients with known epilepsy.
Prevalence
Occurs in ~10% of children who have diagnosis of epilepsy
Age
More common in children, especially in first year of life
More common in patients older than age 60
Sex
Occurs equally in males and females

Risk Factors
Anticonvulsant withdrawal or noncompliance
Previous incident of status epilepticus (SE)
Refractory epilepsy
Head trauma
Metabolic disturbances
Drug toxicity
CNS infection
CNS tumors
Cerebrovascular disease
Fever (especially in children)

Etiology
Seizures are caused by a shift in the normal balance of excitation and inhibition within the CNS.
SE occurs in 3 general clinical scenarios.
SE precipitated by focal or global CNS injury
Head trauma
Metabolic disturbance (e.g., hyponatremia, hypoglycemia)
Infection (encephalitis, abscess)
Drugs (both prescription and illicit)
Brain tumor
Stroke (acute or remote), hypoxia
SE as initial presentation of a seizure disorder
SE as exacerbation of known epilepsy
Primary risk factor is noncompliance with medications.
More common in patients with prior history of SE