Update on Pediatric Epilepsy
Classification of seizures and epilepsy
The International League Against Epilepsy (ILAE) defines a seizure as “a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain” [1]. Diagnosis of seizures and epilepsy largely depends on being able to identify a seizure clinically. However, most seizures are not witnessed by medical professionals, and the diagnosis depends on a caregiver’s description.
Most seizures are characterized by unresponsiveness and eye opening. In fact, eye closure during a seizure is a sensitive indicator of pseudoseizure [2]. In addition, most patients who are having a seizure are unresponsive to painful stimuli. Parents of children with staring spells often say that the child does not respond to his or her name being called. This can be the case even with daydreaming. Parents are often asked to shake the child on the shoulder to see if they can abort the staring. If they cannot, it is more likely to be a seizure.
The ILAE has been working on a revision to the organization of seizures and epilepsy for many years. Their recent report has simplified the classification of seizures (Box 1) [3].
Box 1 Classification of seizures
Data from Revised terminology and concepts for organization of seizures and epilepsies: report of the ILAE commission on classification and terminology, 2005-2009. Epilepsia 2010;51(4):676–85.
It is to be noted that the term “focal” is used instead of “partial.” Focal seizures are no longer broken down into “complex partial” and “simple partial”. This terminology was thought to be confusing and misused. It is also to be noted that the use of simple and complex in terms of febrile seizures is completely unrelated to simple and complex partial seizures. Nevertheless, the commission recognizes that it is important to describe any alteration of consciousness as part of a seizure [3].
Classification of epilepsy
The epilepsies have a separate classification from seizures. For example, a patient has to have an absence seizure to have absence epilepsy, but patients with childhood absence epilepsy can have other types of seizures as well. Epilepsy describes a propensity for seizures because of an “enduring alteration in the brain” [1]. This alteration can be because of a known underlying structural cause, such as a remote encephalitis, or it can be because of a known epilepsy syndrome. The 1989 international classification of epilepsies categorized epilepsy syndromes as “idiopathic,” “symptomatic,” and “crytogenic” [4]. These terms have been abandoned because of their inaccuracy and inconsistency with new genetic and neuroscience knowledge. The commission now recognizes epilepsies called “electroclinical syndromes” (Box 2). These are a cluster of clinical symptoms and electroencephalographic (EEG) characteristics that appear at certain ages. In addition, there are “distinctive constellations,” which are also recognizable clusters of clinical symptoms but do not have the strong developmental component of the electroclinical syndromes.
Box 2 Electroclinical syndromes and other epilepsies (abbreviated)
Data from Revised terminology and concepts for organization of seizures and epilepsies: report of the ILAE commission on classification and terminology, 2005–2009. Epilepsia 2010;51(4):676–85.
Approach to seizures and epilepsy
Besides an increase in respiratory secretions, other autonomic changes are frequently noted during a seizure. Most patients with complex partial seizure or generalized tonic-clonic seizures have tachycardia and hypertension. Changes in respiratory rate in either direction are frequent as well. In most seizure patients who have not been given antiepileptic medication, the cardiopulmonary changes are not severe enough to require resuscitation and mechanical ventilatory support. Other autonomic changes during a seizure can include flushing, pallor, sweating, bilateral pupillary dilation, abdominal pain, vomiting, and urinary incontinence [5].
After the patient is stabilized, a complete history and physical examination can be obtained. Questions and examination should be directed in an attempt to determine the cause of the seizure. Table 1 lists the common causes of seizures and the studies that can be done to help confirm the diagnosis.
Table 1 Common causes of seizures
Cause of Seizure | Suggested Studies |
---|---|
Metabolic abnormalities: hypoglycemia or hyperglycemia, hyponatremia or hypernatremia, hypocalcemia or hypercalcemia, hypomagnesemia, uremia, liver failure, hyperammonemia | Basic chemistries, calcium and magnesium levels, liver function tests, ammonia levels |
Infection: meningoencephalitis, sepsis, neurocysticercosis | Lumbar puncture, send cerebrospinal fluid for appropriate infectious titers/PCR, sepsis evaluation, head CT, MRI with gadolinium |
Neoplasm, vascular malformation | Head CT, MRI with gadolinium |
Trauma | Head CT |
Inherited neurodegenerative disorder | Appropriate genetic testing |
Toxic causes, drug withdrawal | Urine toxicology screen, ethanol levels, other specific drug tests |
Perinatal stroke/asphyxia | Head CT, MRI |
Congenital brain malformation | Head CT, MRI |
Febrile seizure | Lumbar puncture in selected cases |
Epilepsy | EEG, antiepileptic drug levels (to check for compliance) |
Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging; PCR, polymerase chain reaction.
With an accurate history and physical examination, few to none of the studies in Table 1 will need to be performed acutely. Conversely, children with known epilepsy should still have investigations into the secondary causes of seizure, such as infection and trauma, if clinically warranted. The main piece of clinical information to obtain is to determine whether the child has returned to his or her baseline neurologic status. These children are only likely to need further studies on an outpatient basis. Children who remain lethargic after an appropriate postictal period need continued monitoring, possible admission, and further studies, such as lumbar puncture for viral encephalitis or subarachnoid hemorrhage or computed tomography of the head for subdural hematoma or hydrocephalus.
All children with a first-time afebrile seizure without an obvious secondary cause such as trauma should have an EEG [6]. EEG can be done as an outpatient if the patient is at the baseline neurologic status when presenting after the seizure. Antiepileptic drug therapy is generally not recommended after a first seizure, but this decision should be individualized [7]. There is no evidence that treating after the second seizure, as opposed to the first seizure, changes the long-term course or prognosis of the patient’s epilepsy.