Status Epilepticus

Karim Rafaat, MD

Definition

• Single seizure lasting greater than 30 minutes OR

• Series of seizures lasting 30 minutes or longer without full return of consciousness between seizures

Pathophysiology

• Status occurs because of failure of the normal mechanisms that limit the spread and recurrence of isolated seizures– Excitation is excessive and/or inhibition

is ineffective

Pathophysiology

• Excitatory– Glutamate

• Major amino acid excitatory neurotransmitter in the brain

• Role in the pathogenesis of SE was suggested by an outbreak of illness caused by eating mussels contaminated with domoic acid, an analogue of glutamate

– Aspartate– Acetylcholine

Pathophysiology

• Inhibitory– Gamma-aminobutyric acid (GABA)

• Main inhibitory neurotransmitter in the brain• Antagonists to its effects or alterations in its

metabolism in the substantia nigra may contribute to SE

– Calcium ion-dependent potassium ion current

– Blockage of NMDA channels by magnesium

Subtypes of Status

• Convulsive– Primary generalized– Simple of complex partial– Secondary generalized

• Nonconvulsive– Absence status– Complex partial status– Atonia (electromechanical dissociation)

• “Give Me a Break”– Pseudoseizures

Epidemiology

• Status epilepticus occurs in 5-15% of patients with epilepsy

• Status is more common in childhood than adulthood

• Approximately 10% of children with epilepsy have status on initial presentation

• In children the seizure is usually generalized from the onset (often a partial seizure with secondary generalization in adults)

Causes of Status• Reactive

• Fever• Metabolic Alterations (hyponatremia, hypocalcemia,

hypoglycemia)• Symptomatic

– Acute• Infection• Hypoxia• Trauma• Hemorrhage/Stroke

– Remote• Perinatal Hypoxic-Ischemic Injury• Trauma• Infection• Congenital Brain Malformation

• Idiopathic or Cryptogenic

Physiological Changes During Status Epilepticus• Hypoxia

– Responsible for the majority of morbidity and mortality in patients with status

– Results from:• impaired mechanical ventilation by muscle

spasms• increased salivation and secretions in lungs• increased oxygen consumption with the

increased demands from muscle and brain tissue

Physiological Changes During Status Epilepticus• Respiratory Acidosis

– Results from impaired ventilation and increased metabolic production of carbon dioxide

• Metabolic Acidosis– Predominantly lactic acidosis from

impaired tissue oxygenation and perfusion

Physiological Changes During Status Epilepticus• Elevated WBC

– Peripheral leukocytosis in 50-60%– CSF pleocytosis in 10-15%

• Hyperkalemia• Increased muscle enzymes

– Rhabdomyolysis results in myoglobinuria

– May result in ATN/acute renal failure

Physiological Changes During Status Epilepticus• Hyperglycemia

– Associated with sympathetic discharge and increased hepatic gluconeogenesis

• Hypoglycemia– Develops after approximately 60

minutes of seizure activity– Associated with increased consumption

by brain and muscles during seizures

Neurological Changes During Status Epilepticus• Most frequent neurological changes

– Pupillary changes– Increased or decreased tone– Positive Babinski sign

• Result from electrical activity, underlying neurological disease, or metabolic disturbance

• May be bilateral or asymmetrical

EEG Changes During Status Epilepticus• Attenuation of background activity• Generalized low voltage fast activity• Epileptic recruiting rhythm with increased

amplitude and decreased frequency• Generalized polyspike and slow discharges

with repetition rate of 1-4Hz• Diffuse depression of background activity

after cessation of seizure

Systemic Changes During Early Status Epilepticus• Hypertension, tachycardia

– Caused by massive catecholamine release and autonomic discharge• Cardiac output increases• Mean arterial pressure increases

• Hyperpyrexia– Caused by excessive muscle activity

Cerebral Changes During Early Status Epilepticus• Increased ICP

– Cerebral blood flow increases 5-7 times• Results from both cerebral vasodilatation

and systemic hypertension

– Metabolic rate increases 2-5 times• Oxygen and glucose utilization increase

Cerebral Changes as Status Epilepticus ProgressesCerebral blood flow decreases

– Cerebral autoregulation is compromised– Brain oxygenation decreases

• Brain glucose levels decrease – Metabolic demands are higher than supply

• Brain damage generally starts to occur after 30-60 minutes of status – Occurs earlier/more profound with persistent

hypoxia

Pharmacotherapy for Status Epilepticus• Ideal medication

– Effective against all seizures– Several routes of administration– Potent so small volumes can be given rapidly– Cross blood brain barrier rapidly for fast onset – Long half life for long activity– Safe

• No cardiorespiratory depression• No systemic side effects

• Remember to treat the underlying cause

Lorazepam (Ativan)

• Benzodiazepene/GABA agonist• Dose: 0.05-0.1mg/kg (max 4mg)• Route: IV, ET• Onset of action: 2-3 minutes• Duration of Action: 4-14 hours• Low lipid solubility/small area of

distribution• Metabolized by the liver; no active

metabolites• Respiratory depression occurs in 10% of

pts• Tolerance develops with repeated doses

Diazepam (Valium)

• Benzodiazepene/GABA agonist• Dose: 0.2-0.5mg/kg (max 10mg)• Route: IV, ET, IM, PR• Onset of action: 1-3 minutes• Duration of action: 20 minutes• Highly lipophilic/large volume of

distribution• Metabolized by the liver/metabolite is N-

desmethydiazepam which accumulates• Respiratory depression develops in 10%

Midazolam (Versed)

• Benzodiazepene/GABA agonist• Dose: 0.05-0.2mg/kg• Route: IV, IM• Onset of action: 1-5 minutes• Duration of action: 1-2 hours• Continuous drip more effective long-term

than bolus doses• Highly lipophilic/large volume of

distribution• Metabolized by the liver• Side effects: bradycardia, hypotension

Phenytoin (Dilantin)• Dose: 18-20mg/kg• Route: IV• Onset of action: 10-30 minutes• Duration of action: 12-24 hours• Maximal infusion rate: 50mg/min• Cardiac arrythmias and hypotension can

result from rapid administration• Risk of thrombophlebitis and tissue

necrosis with infiltration• Highly lipid soluble, but not water soluble• Metabolized by the liver

Fosphenytoin (Cerebyx)

• Prodrug of phenytoin– Phosphate ester group is removed from drug

once in enters bloodstream• Same dose, onset of action, duration of

action as phenytoin• Route: IV, IM• Maximal infusion rate: 150mg/min• Water soluble• Less risk of thrombophlebitis, tissue

necrosis with extravasation• 10 times more expensive than phenytoin

Phenobarbital (Luminal)

• Loading dose: 10-20mg/kg• Route: IV, IM, PO• Onset of action: 15-60 minutes• Duration of action: 24-96 hours• Maximal infusion rate: 100mg/min• Side effects: sedation, hypotension,

respiratory suppression• Dose needs to be adjusted in renal or

hepatic failure

Thiopental (Pentathol)

• Loading dose: 12mg/kg• Continuous dose: 3-5mg/kg/hr• Onset of action: 20-60 minutes• Hypotension is common/pressors often

needed • Infiltrate can cause tissue necrosis• Tolerance develops • Intermittent EEG should be followed• Metabolized to pentobarbital by the liver

– Thiopental and pentobarb levels are followed

Pentobarbital (Nembutal)

• Barbiturate/GABA agonist• Loading dose: 5-12mg/kg• Continuous dose: 0.5-1mg/kg/hr• Onset of action: 10-20 minutes• Hypotension is common/pressors often

required• Ileus/feeding intolerance is common• Requires intermittent EEG monitoring to

assess sedation

Isoflorane (Forane)

• Liquid anesthetic agent• Route: inhaled• Onset of action: 1-2 minutes• Eliminated by exhalation/little to no risk of

hepatotoxicity (unlike halothane)• May cause hypotension requiring pressors • Impractical in ICU setting since it requires

facilities for administration of continuous inhaled anesthetic

Etomidate (Adimate)

• IV anesthetic agent• Dose: 0.3mg/kg• Route: IV continuous infusion• Onset of action: 1-2 minutes• Metabolized by the liver• Patients may develop myoclonus or

muscle twitches unassociated with epileptic activity

• Long term infusion results in adrenal suppression– Corticosteroids are required

Propofol (Diprivate)

• IV anesthetic agent• Loading dose: 1.5mg/kg/hr• Maintenance dose: 6-10mg/kg/hr• Onset of action: 1-2 minutes• Rapidly metabolized by the liver• Patients may develop involuntary muscle

twitches unassociated with EEG activity• Marked lipidemia occurs with prolonged

use• No adrenal side effects

Treatment Protocol for Status Epilepticus• <1 minute

– Establish airway– Assess respirations and blood pressure– Establish IV access– Draw labs

• Chem 7, divalents, CBC, accucheck in all• AED drug levels, tox screen, cultures when

appropriate

• <2 minutes– Lorazepam 0.05-0.1mg/kg IV (ET if n– Diazepam PR, midazolam IM if needed

Treatment Protocol for Status Epilepticus• <15 minutes

– Phenytoin or fosphenytoin load • Slow infusion rate if hypotensive, arrythmias

– Phenobarbital load if allergic to phenytoin• <60 minutes

– Midazolam load/drip if seizures persist• Titrate to seizure cessation or burst suppression on

EEG– Correct any metabolic disturbances found

• >60 minutes– Pentobarbital load/drip if seizures persist

• Titrate to burst-suppression on EEG

Complications

• Neuronal cell damage/death• Aspiration pneumonia• Neurologic pulmonary edema• Rhabdomyolysis• Hyperthermia• Cardiac arrythmias• Medication complications:

– Respiratory depression– Hypotension– Bradycardia– Ileus

Recurrent Seizures

• Risk factors for recurrent seizures :– 1st seizure is status epilepticus– Remote symptomatic etiology– Abnormal EEG– Seizure during sleep– History of prior febrile seizure– Todd’s paresis

Neurologic Sequelae

• Variable rates of neurologic sequelae• Neurologic outcome depends

primarily on the underlying condition• One review demostrated 6 to 15

percent rate of encephalopathy and neurologic deficits

Age and Prognosis

• Overall children have better outcomes than adults

• Poorer prognosis at extremes of age– Adult mortality rate 25%– Pediatric mortality rate 5%

• Age under 1 year: 25%• Age 1-3 years: 10%

• Differences in outcomes thought to be based on different etiologies in these age groups

Outcomes in Status Epilepticus• Mortality is related to underlying cause

– 90% of patients with status from AED withdrawal, alcohol abuse, or trauma do well

– 33% of patients with status from stroke, anoxia, or major metabolic disturbance do well

• Majority of morbidity results from hypoxia– More closely related to duration of hypoxia

rather than duration of seizure activity• But patients who seize for more than 60 minutes

have worse outcomes than those who seize for less

Refractory Status Epilepticus• Persistent seizure activity despite

appropriate therapy– Associated with high mortality and morbidity– Retrospective review of 22 pts tx’d 1992-2000

with high-dose anesthetic agents for 2 to 146 days (median 16.5 days)• Mortality was 32%• Greater in younger patients and in those with

multifocal or generalized abnormalities on EEG• All except one survivor developed active epilepsy and

none with a normal neurologic status prior to the event returned to their baseline

Adjunctive Therapy: the Ketogenic Diet• High fat (80-90% of calories), low protein,

very low carb diet developed in 1900’s • Ketosis is induced by starvation for 1-2

days, then perpetuated by ketogenic diet• Diet alters metabolism to replace glucose

with fats as the body’s main energy source• Ketone bodies may have an antiepileptic

effect (mechanism not understood)• Many observation studies report good

results– 1/3 sz resolution; 1/3 sz improved; 1/3

unchanged• No randomized clinical trials in the

literature

Future Potential Therapy

• NMDA antagonists and other calcium entry channel blockers

• Glutamine antagonists– Limited secondary to psychiatric effects