Seizures

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Chapter 39 SEIZURES

Timothy J. Horita and Theodore X. O’Connell

General Discussion

Seizures are the most common pediatric neurologic disorder, with 4% to 10% of children suffering at least one seizure in the first 16 years of life. The incidence is highest in children younger than 3 years of age and decreases with increasing age. A seizure is defined as a transient, involuntary alteration of consciousness, behavior, motor activity, sensation, or autonomic function caused by a paroxysmal electrical discharge of neurons in the brain. A postictal period of decreased responsiveness usually follows most seizures, and the duration of the postictal period is proportional to the duration of seizure activity. Epilepsy describes a condition of susceptibility to recurrent seizures. Status epilepticus refers to continuous or recurrent seizure activity lasting longer than 30 minutes without recovery of consciousness.

Classification systems have been developed to standardize the terminology used to describe seizure activity. Two overall seizure types exist: partial and generalized. Partial seizures originate in one cerebral hemisphere. Partial seizures are further subdivided based on whether they result in an altered level of consciousness. A simple partial seizure has no impairment of consciousness and most commonly manifests as abnormal motor activity. Autonomic, somatosensory, and psychic symptoms can also occur. A complex partial seizure occurs when an alteration of consciousness is present. An aura consisting of abnormal perception or hallucination often precedes this type of seizure. Both simple and complex partial seizures may ultimately become generalized.

A generalized seizure involves both cerebral hemispheres and may involve a depressed level of consciousness. Generalized seizures are either convulsive, with bilateral motor activity, or nonconvulsive. Types of generalized seizures include tonic-clonic (also known as grand mal), tonic, clonic, myoclonic, atonic-akinetic (drop attacks), or absence (petit mal).

The immature neonatal brain is more excitable than that of an older child and is more susceptible to seizure activity. However, the resulting seizures may be subtle and difficult to discern from other normal newborn movements or activities. Lip smacking, eye deviations, or apneic episodes may be the only manifestations of seizure activity in this age group.

A seizure represents a clinical symptom of an underlying pathologic process with many possible causes. These causes are outlined below. When a child presents with a seizure, every effort should be made to determine the cause. It is important to differentiate between a seizure and other nonepileptic conditions that may mimic seizure activity.

The topic of febrile seizures is reviewed in Chapter 17.

Medications and Toxins Associated with Seizures

• Propoxyphene

• Salicylates

Anticonvulsants (from withdrawal)

• Carbamazepine

Cellular Asphyxiants

• Carbon monoxide

• Hydrogen sulfide

Drugs of Abuse

• Amphetamines

• γ-Hydroxybutyratic acid (GHB)

Envenomations

Heavy Metals

Plants, Herbs, and Natural Products

• Gyromitra esculenta mushroom

• Water hemlock

Psychiatric Medications

• Cyclic antidepressants

• Phencyclidine

• Phenothiazines

• Selective serotonin reuptake inhibitors (SSRIs)

• Venlafaxine

Rodenticides

• Bromethalin

• Zinc phosphide

• Anticonvulsants

• Sedative-hypnotics

Miscellaneous

Causes of Seizures

• Brain abscess

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