Seizures in which the primary clinical feature is staring can beeither absence (generalized) or complex partial seizures. Theclinical hallmark of absence seizures is a brief (less than 15 seconds) loss of environmental awareness accompanied by eye fluttering or simple automatisms, such as fumbling with the fingersand lip smacking. Absence seizures usually begin between 4and 6 years of age. Neurologic examination and brain imagingare normal. The characteristic electroencephalographic (EEG)patterns consist of generalized 3-Hz spike-and-wave activity. A clinical seizure can be provoked by hyperventilation or strobe light stimulation. Differentiating absence from complexpartial seizures can be difficult, but is essential for appropriateevaluation and treatment (Table 181-4).
Atypical Absence, Myoclonic, and Atonic Seizures
Atypical absence seizures manifest as episodes of impaired consciousness with automatisms, autonomic phenomena, and motor manifestations, such as eye opening, eye deviation, and body stiffening. They are associated with slower EEG discharges (2 Hz) and other seizure types. Myoclonus is a sudden jerk of all or part of the body; not all myoclonus is epileptic in nature. Nonepileptic myoclonus may be benign, as in sleep myoclonus, or indicate serious disease. Myoclonic epilepsy usually is associated with multiple seizure types. The underlying disorder producing myoclonic epilepsy may be static (juvenile myoclonic epilepsy) or progressive and associated with neurologic deterioration (neuronal ceroid lipofuscinosis). Myoclonic absence refers to the body jerks that commonly accompany absence seizures and atypical absence seizures. Although atonic seizures are typically brief (lasting 1 to 2 seconds), they are quite disabling because of a sudden loss of postural tone, resulting in falls and injuries.
Seizures in the setting of fever may be caused by infections of the nervous system (meningitis, encephalitis, brainabscess), unrecognized epilepsy triggered by fever, or febrile seizures. The latter represents the most common cause ofseizures among children between 6 months and 6 years of age, occurring in about 4% of all children. By definition, a febrile seizure occurs in the presence of fever. Simple febrile seizures are generalized at onset, last less than 15 minutes, and occur only once in a 24-hour period in a neurologicallyand developmentally normal child. If there are focal features,the seizure lasts longer than 15 minutes or recurs within 24hours, or if the child has preexisting neurologic challenges,the seizure is referred to as a complex or atypical febrile seizure.
The prognosis of children with simple febrile convulsionsis excellent. Intellectual achievements are normal. Febrile seizures recur in 30% to 50% of children. The risk of subsequentepilepsy is not substantially greater than that for the generalpopulation (approximately 2%). Factors that increase the riskfor the development of epilepsy include abnormal neurologicexamination or development, family history of epilepsy, andcomplex febrile seizures. Because febrile seizures are briefand the outcome is benign, most children require no treatment. Rectal diazepam can be administered during a seizureto abort a prolonged event and is a reasonable option forchildren with a history of prolonged febrile seizures. Becauseof the potential for side effects, daily administration of anticonvulsant medication is not recommended. Administration of antipyretics during febrile illnesses does not preventfebrile seizures.