Seizures
Seizures: Excerpt from Pediatric Complaints and Diagnostic Dilemmas
Samir S. Shah
Approach to the Patient with Seizures
I. Definition of the Complaint
Seizures, a common neurologic disorder of childhood, occur in 4% to 6% of all
children. A seizure is defined as a transient, involuntary alteration of
consciousness, behavior, motor activity, sensation, and/or autonomic function
that is caused by an excessive rate and hypersynchrony of discharges from a
group of cerebral neurons. A seizure disorder, or epilepsy, is a condition of
susceptibility to recurrent seizures. This chapter discusses possible causes of
seizures. The classification of seizure types can be found in standard
pediatrics textbooks.
The first step in formulating a differential diagnosis for a child who presents
with
“seizures” is to characterize the type of event that has occurred. Seizures should be
differentiated from other childhood paroxysmal events that can mimic seizure
activity. Syncope is the most common alternative diagnosis given to patients
who present for evaluation of a suspected seizure episode. Gastroesophageal
reflux with opisthotonic posturing (Sandifer syndrome) frequently mimics
seizures in infancy. Breath-holding spells, which occur in approximately 4% of
infants, can resemble seizures and are also associated with cyanosis. A variety
of movement disorders, such as benign myoclonus of infancy and Tourette
syndrome, may also be mistaken for seizures. Additionally, seizure activity is
often subtle, making seizures difficult to diagnose. For example, in the
neonatal period seizures may manifest with horizontal eye movements, repetitive
sucking, or pedaling and stepping motions that are difficult to distinguish
from normal newborn infant activity.
II. Complaint by Cause and Frequency
A seizure does not constitute a diagnosis but is a symptom of an underlying
pathologic process that requires a thorough evaluation. The causes of seizures
in childhood vary by age (Table 19-1) and may also be grouped by etiology
(Table 19-2): (a) infectious, (b) toxicologic, (c) metabolic, (d) vascular, (e)
oncologic, (f) endocrine, (g) traumatic, (h) congenital, and
(i) idiopathic.
III. Clarifying Questions
Thorough history taking is essential to arriving at an accurate diagnosis in a
child who presents with seizures. Consideration of seizure type, precipitating
factors, and associated clinical features provides a useful framework for
creating a differential diagnosis. The following questions may help provide
clues to the diagnosis.
• Did the seizure involve the entire body or only a portion?
— Partial, or focal, seizures reflect initial involvement limited to one cerebral
hemisphere and are further classified based on whether consciousness is
impaired. Partial seizures are less common in children than in adults. Although
partial seizures are more likely to be associated with focal hemispheric
lesions than are generalized seizures, such structural causes are only found in
30% to 50% of cases. Children with congenital heart disease or right-to-left
shunts may have cerebral emboli resulting in neurologic deficits and partial
seizures. Herpes simplex virus (HSV) can cause seizures with a temporal lobe
focus. Partial seizures occur later in childhood in individuals with heritable
familial degenerative disorders that are characterized by storage
abnormalities, such as GM1 and GM2 gangliosidoses. Parasitic infections such as
echinococcosis and cysticercosis also cause focal brain lesions predisposing to
partial seizures.
• Was there a preceding illness or fever?
— Febrile seizures occur most commonly in children younger than 5 years of age.
Infectious causes must be excluded, because seizures are often the initial
manifestation of bacterial meningitis in infants and children.
• Has there been an ingestion or toxin exposure?
— Many medications and environmental toxins can lead to seizures, including
anticonvulsant medications, hypoglycemic agents, isoniazid, lithium,
methylxanthines, heavy metals (lead), and tricyclic antidepressants.
• Is there a history of recent headache, vomiting, lethargy, weakness, or
alteration in gait?
— These symptoms suggest underlying central nervous system (CNS) pathology and the need for neuroimaging. In the neonate, the early onset
of lethargy, vomiting, and seizures should prompt an evaluation for an
underlying metabolic disorder such as an aminoacidopathy, organic aciduria, or
urea cycle defect; examples include phenylketonuria and maple syrup urine
disease.
• Is there a history of previous seizures (febrile or afebrile) or neurologic
abnormality?
— One third of children with a simple febrile seizure have a second episode. A
previous afebrile seizure or existing neurologic abnormality increases the
likelihood of a seizure disorder or epileptic syndrome.
• Is there a history of head trauma?
— Head trauma can result in epilepsy at any age. Seizures can occur within 1 to 2
weeks after the injury (early posttraumatic seizures), as an acute reaction to
head trauma, or after intervals of several months or even years (late
posttraumatic seizures). The risk of developing seizures is related to the
severity of the head injury. The child with a mild head injury (transient loss
of consciousness without evidence of skull fracture or neurologic abnormality)
is not at significantly higher risk than the general population. Moderate head
injuries are associated with an incidence of epilepsy ranging from 2% to 10%.
Children with severe head injuries, such as intracerebral hematoma or a history
of unconsciousness lasting longer than 24 hours, have a 30% risk of developing
epilepsy.
• Is there a history of a remote neurologic insult?
— A history of anoxic birth injury, cerebral palsy, stroke, intracranial
hemorrhage, or meningitis places the child at increased risk for seizure
disorder. Intrauterine infection with cytomegalovirus, toxoplasma, or rubella
is known to cause abnormal brain development and to predispose the child to
seizures.
• Are there skin findings on physical examination, such as café-au-lait spots, ash leaf spots, or cutaneous vascular malformations?
— These findings suggest an underlying neurocutaneous disorder such as
neurofibromatosis, tuberous sclerosis, ataxia-telangiectasia, or Sturge-Weber
syndrome.
• What is the child's head morphology?
— Microcephaly suggests an underlying neurologic abnormality. A full or bulging
fontanel can signify elevated intracranial pressure due to meningitis, trauma,
or malignancy.
• Is there a family history of seizures?
— Both febrile and afebrile seizures can be hereditary.
The following cases represent less common causes of seizures in childhood.
Pictures
Book Source Details
- Book Title: Pediatric Complaints and Diagnostic Dilemmas
- Author(s): Samir S Shah MD; Stephen Ludwig MD
- Year of Publication: 2003
- Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Seizures - Case 19-3: 8-Month-Old Boy (Pediatric Complaints and Diagnostic Dilemmas)
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