Status epilepticus (SE) is defined as a seizure that lasts more than 30 minutes. The annual incidence of convulsive SE among children in developed countries is about 20 per 100,000 population.

Essential update: Persistent developmental impairment after status epilepticus in young children

Convulsive SE (CSE) produces early deficits in cognition and language that persist at 1 year, according to a study in children from 1 to 42 months of age—27 with nonfebrile CSE, 27 with persistent febrile seizures (PFS), and 17 healthy controls. On baseline neurodevelopmental studies conducted within 6 weeks after the seizures, the children with nonfebrile CSE scored worse than those with PFS, who in turn scored worse than the controls. Follow-up testing 1 year later revealed no difference in performance from baseline for either the PFS or nonfebrile CSE groups.^{[1, 2]}

Signs and symptoms

Generalized tonic-clonic SE (GTCSE) has 3 phases, which have the following characteristics:

• Phase 1: Discrete partial seizures or, less frequently, generalized seizures; blood pressure usually remains within the reference range
• Phase 2: Discrete SE events fuse and partial seizures become secondarily generalized; the main outward manifestation of continuous seizure activity consists of a tonic phase (sustained muscle contraction) followed by clonic jerks (alternating contraction and relaxation of the 4 limbs); alteration of blood pressure may occur
• Phase 3: Clinical seizures may become quite subtle, with brief rhythmic clonic or myoclonic movements often restricted to a single part of the body; rhythmic activity may be observed as myoclonus that affects only the feet, hands, facial muscles, or eyes (as nystagmus); hyperthermia, respiratory compromise, hypotension, and hypoglycemia may be observed

Nonconvulsive status epilepticus has the following characteristics:

• Patients appear forgetful and sleepy, behaving as if deaf and blind (“like a zombie”) or drugged
• In more severe cases, patients are described as unresponsive
• Parents may describe frequent falls, poor motor control, or abnormal balance

Patients with absence SE present with the following:

• Altered consciousness, with or without clonic movements of the eyelids or upper extremities
• Automatisms involving the hands and face
• A child may sometimes continue to perform a motor act that he or she was engaged in before onset of the absence seizure (eg, bouncing a basketball)
• In some cases, the patient may answer simple questions, but detailed examination reveals slowed mentation and poor processing of complex information
• Episodes of absence SE may last 12 hours or longer

When the patient's situation stabilizes, look for lymphadenopathy, which suggests catscratch fever.

See Clinical Presentation for more detail.

Diagnosis

Every patient who presents with SE requires an EEG; however, treatment should not be delayed to wait for EEG results. When a seizure persists longer than 30-60 minutes, making immediate arrangements for an EEG is advisable. Features of testing and procedures are as follows:

• Laboratory testing should proceed concurrently with stabilization
• Lumbar puncture with opening pressure measurement is performed for prolonged SE of unknown etiology and in immunocompromised patients
• Obtain imaging studies based on likely etiologies; stabilize all children before performing CT scanning or other imaging studies

SE persisting beyond 24 hours needs further workup if routine blood work, brain MRI, and microbiological studies in serum and CSF do not provide clues to the etiology of the seizures. The following investigations are considered:

• Urine organic acids, porphyrins (porphyria), and sulfites (sulfite oxidase deficiency and molybdenum co-factor deficiency)
• Serum T4, T3, thyrotropin, and antiperoxidase antibody (autoimmune epilepsy)
• Serological markers for collagen-vascular disorders
• Serum and CSF NMDA-R antibody, ultrasound/CT/MRI of testes and abdomen to look for solid tumors (anti NMDA-R antibody encephalitis)
• Other paraneoplastic antibodies (anti Hu, Yo, Ri)

See Workup for more detail.

Management

Treatment of SE should be based on an institutional protocol, such as the following:

• Attend to the ABCs before starting any pharmacologic intervention
• Place patients in the lateral decubitus position to avoid aspiration of emesis and to prevent epiglottis closure over the glottis
• Make further adjustments of the head and neck if necessary to improve airway patency
• Immobilize the cervical spine if trauma is suspected
• Administer 100% oxygen by facemask
• Assist ventilation and use artificial airways (eg, endotracheal intubation) as needed
• Suction secretions and decompress the stomach with a nasogastric tube.
• Carefully monitor vital signs, including blood pressure
• Carefully monitor the patient's temperature, as hyperthermia may worsen brain damage
• In the first 5 minutes of seizure activity, before starting any medications, try to establish IV access and to obtain samples for laboratory tests and for seizure medication
• Infuse isotonic IV fluids plus glucose at a rate of 20 mL/kg/h (eg, 200 mL D5NS over 1 h for a 10-kg child)
• In children younger than 6 years, use intraosseous (IO) infusion if IV access cannot be established within 5-10 minutes
• If serum glucose is low or cannot be measured, give children 2 mL/kg of 25% glucose
• If the seizure fails to stop within 4-5 minutes, prompt administration of anticonvulsants may be indicated

Anticonvulsant selection can be based on seizure duration, as follows:

• 6-15 min: Lorazepam (0.05-0.1 mg/kg IV or IO slowly infused over 2-5 min); or diazepam per rectum at 0.5 mg/kg, not to exceed 10 mg
• 16-35 min: Phenytoin (Dilantin) or fosphenytoin, not to exceed infusion rate of 1 mg/kg/min; do not dilute in D5W; if unsuccessful, phenobarbital 10-20 mg/kg IV (not to exceed 700 mg IV); increase infusion rate by 100 mg/min; phenobarbital may be used in infants before phenytoin
• 45-60 min: Pentobarbital anesthesia (patient already intubated); or midazolam, loading dose 0.1-0.3 mg/kg IV followed by continuous IV infusion at a rate of 0.1-0.3 mg/kg/h

Pentobarbital anesthesia is administered as follows:

• Loading dose: 5-7 mg/kg IV
• May repeat 1-mg/kg to 5-mg/kg boluses until EEG exhibits burst suppression; closely monitor hemodynamics and support blood pressure as indicated
• Maintenance dose: 0.5-3 mg/kg/h IV; monitor EEG to keep burst suppression pattern at 2-8 bursts/min

Other specific treatments may be indicated if the clinical evaluation identifies precipitants of the seizures. Selected agents and indications are as follows:

• Naloxone - 0.1 mg/kg/dose, IV preferably (if needed may administer IM or SQ) for narcotic overdose
• Pyridoxine - 50-100 mg IV/IM for possible dependency, deficiency, or isoniazid toxicity
• Antibiotics - If meningitis is strongly suspected, initiate treatment with antibiotics prior to CSF analysis or CNS imaging

See Treatment and Medication for more detail.

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