Pediatric Seizures

Objectives

• Understand the difference between focal and generalized seizures and be able to describe basic seizure semiology
• Describe the characteristics of febrile seizures
• Discuss the diagnostic criteria for status epilepticus
• Understand the diagnostic approach to patients presenting with a first-time seizure
• List common anticonvulsants used for treatment of seizures in the emergency department
  

Introduction

A seizure or convulsion is an abrupt change in motor activity or behavior that is triggered by an abnormal electrical stimulus in the brain.  Seizures may be a manifestation of life threatening conditions such as meningitis and intracranial bleeding or may be due to common childhood conditions such as febrile seizures.  It is critical to gather key elements of the history and physical in order to guide the workup in the emergency department.

Initial Actions and Primary Survey

Emergency department evaluation during or shortly after a seizure should begin with assessment of the patient’s airway, breathing, and circulation.  Patients who are actively seizing should be immediately turned on their side to prevent aspiration.  Provide supplemental oxygen or advanced airway support as needed.  Along with vital signs, a bedside glucose may be obtained as hypoglycemia is a common cause of seizure.

Next, the semiology of the seizure should be carefully noted by the clinician.

Some important characteristics to note include:

• Type of seizure:
  • Tonic-clonic – rhythmic shaking with increased tone
  • Myoclonic – sudden muscle contractions or spasms
  • Atonic – sudden loss of muscle tone (sometimes called “drop attacks”)
  • Absence – brief episode of staring followed by quick return to baseline (“staring spells”)
• Location – Does the seizure involve the entire body (generalized) or is it limited to one extremity/side (focal)?
• Eyes – Are the pupils midline or deviated to the right/left? Note the pupil size as well.
• Duration – Note the time that the patient was convulsing as well as the time it took from the end of the convulsion until the return to the patient’s baseline neurologic function (post-ictal period).

If the seizure lasts longer than 5 minutes, it is appropriate to give a medication to stop the seizure.  First line therapy is administration of a benzodiazepine.  Treatment will be discussed in more detail later in the chapter.

Presentation

Most patients will present to the emergency department after the seizure activity has already stopped.  It is important to ask the family or caregivers questions about the seizure characteristics.  Medical history can also be very helpful. 

Important questions to ask include:

• History of prior seizures
• Recent fever
• Family history of seizures
• Presence of preceding aura or headache
• Recent head trauma
• Ingestion of drugs or toxins
• History of other neurologic disorders or chronic medical problems
• Immunization status

Febrile seizures account for the majority of seizures in pediatric patients and occur in 2-5% of all children.  They occur between the ages of six months and six years with peak incidence between 12-18 months.  Simple febrile seizures are generalized tonic-clonic in nature, last less than 10 minutes, and do not recur in a 24 hour period; events that are focal, prolonged, or recur within a 24 hour period are termed complex febrile seizures.  While approximately one third of children with febrile seizures will have a recurrence before age six, simple febrile seizures do not increase a child’s risk of developing epilepsy in the future.  Children with simple febrile seizures have a 1-2% risk of developing epilepsy and those with complex febrile seizures have a 5-10%.  The use of antipyretics does not decrease risk of recurrence of febrile seizure.

Epilepsy is a group of central nervous system disorders in which nerve cell conduction becomes disrupted causing seizures.  There are many different types of epilepsy that require detailed diagnostic testing with a pediatric neurologist.  As these evaluations are not typically part of the emergency department evaluation, they will not be discussed here.

Some patients will present to the emergency department with status epilepticus.  In the past, status epilepticus was defined as convulsive seizures that last greater than 30 minutes or two or more seizures that occur in a 30 minute period.  More recently, however, this definition has been revised as we learn that seizures are more likely to respond to pharmacologic therapy if acted upon early.  Currently, any prolonged seizure lasting greater than 5 minutes or recurrent seizures lasting longer than 5 minutes without interval return to full consciousness is considered status epilepticus.  Patients who present to the emergency department with altered mental status or decreased responsiveness may be in subclinical or non-convulsive status epilepticus, and EEG should be considered in these patients.

Diagnostic Testing

A careful physical exam is critical in evaluating a patient after a seizure.  The examiner should do a complete neurologic exam looking for subtle hemiparesis, changes in strength, clonus, and increased/decreased tone.  As infectious causes are often in the differential, patients should be evaluated for meningismus or presence of rash.  The examiner should note any loss of continence to urine or stool that occurred with the seizure.

The majority of seizures in children between six months and six years of age are febrile seizures.  If the history is consistent with a concurrent febrile illness and the neurologic exam is non-focal, no specific testing is required.  Testing may be indicated to elucidate the cause of the fever.

If the patient exhibited a generalized seizure in the absence of fever, an electroencephalogram (EEG) should be performed.  This is typically non-emergent and may be done as an outpatient.  If a focal seizure occurred or there are focal neurologic findings on exam, head imaging with a computed tomography (CT) scan and neurology consult are indicated in the emergency department.  Other studies such as toxicology screening, laboratory tests, and lumbar puncture should be done only when clinically indicated as they are low-yield when used as screening tests.

Treatment

The first step in treatment is ensuring a safe environment for the patient by removing items from the patient’s mouth and lowering the patient to the ground or bed.  Most seizures are self-limited and do not require pharmacologic therapy.

If the seizure persists longer than five minutes, a benzodiazepine should be administered as a first-line agent.  Lorazepam (Ativan) is the preferred agent given its long half-life.  Other agents may be used in the event that the patient does not have intravenous access or if lorazepam is not immediately available.  Diazepam offers the benefits of being stable at room temperature for long periods of time (making it a preferred agent for out-of-hospital use) and is also available in a rectal gel formulation (Diastat) for home use.  Midazolam (Versed) may be administered via intramuscular, intranasal, buccal, or rectal routes, but is not a preferred intravenous agent given its short half-life.  All of these medications are available in oral formulations, but oral medications should never be given to an actively seizing or post-ictal patient.

If a seizure has not stopped after at least two appropriately-dosed trials of a benzodiazepine, a second-line agent should be used.  There are many acceptable second-line agents.  The most commonly used agent is fosphenytoin (Cerebyx), a pro-drug of phenytoin, as it can be rapidly administered.  Other potential second-line agents include phenobarbital (Luminal), valproic acid (Depkote), and levetiracetam (Keppra).  Typical dosing of antiepileptic medications is shown in table 1.

Table 1. Antiepileptic medications for acute seizure management.

Pearls and Pitfalls

• The evaluation of any seizing patient should begin with the ABCs (airway, breathing, circulation).
• Careful observation of seizure characteristics (generalized versus focal, tonic-clonic versus atonic) is helpful in determining workup and management of seizure in the ED.
• Febrile seizures are common (2-5% of children), benign, and usually self-limited. Simple febrile seizures do not increase a child’s risk of epilepsy in the future.
• Status epilepticus is defined as prolonged seizure lasting greater than 5 minutes or multiple seizures without return of consciousness in between events lasting greater than 5 minutes.
• Any seizure lasting longer than 5 minutes should be treated with a benzodiazepine (Lorazepam is the preferred IV agent).
  

References

1. Abend, N., Bearden, D., Helbig, I., et al. (2014). Status Epilepticus and Refractory Status Epilepticus Management. Seminars in Pediatric Neurology 21(4):263-274. PMID: 25727508.
2. Abend, N. Loddenkemper, T. (2014). Pediatric Status Epilepticus Management. Current Opinion in Pediatrics 26(6):668-674. PMID: 25304961.
3. Hirtz, D., Ashwal, S., Berg, D., et al. (2000). Practice Parameter: Evaluating a First Nonfebrile Seizure in Children. Report of the Quality Standards Subcommittee of the American Academy of Neurology, the Child Neurology Society, and the American Epilepsy Society. Neurology 55: 616-623. PMID: 10980722
4. Holsti, M. (2015). Seizures in Infants and Children. In Tintinalli (Ed.),  Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8th Edition (pp. 888-895).
5. Lexicomp Online, Pediatric and Neonatal Lexi-Drugs Online. Hudson, Ohio: Lexicomp, Inc.; 2013 [cited 30 Dec 2015]. Available from: http://online.lexi.com. Subscription required to view.
6. Patel, N., Ram, D., Swiderska, N., Mewasingh, L., Newton, R., Offringa, M. (2015). Febrile Seizures. BMJ351:1-7. PMID: 26286537.