clonic seizures), or both. The terms fits and convulsions are frequently used synonyms for motor seizures. In addition, seizures can occur with or without fever. Febrile seizures are well-defined, relatively common events that are precipitated by fever in children under 5 years of age who do not harbor an underlying seizure disorder. If more than one seizure occurs within 24 hours or if the seizures last longer than 10 minutes or are accompanied by transient focal neurologic features, they are termed complex febrile seizures. Acute symptomatic seizures are those that occur in association with an acute process that affects the brain, such as head trauma or a bacterial infection. Afebrile seizures are those that occur in the absence of fever or other acute provocation. Recurrent afebrile seizures are referred to as epilepsy. Infantile spasms are a type of epileptic disorder in young children and are characterized by flexor, extensor, and mixed flexor-extensor seizures that tend to occur in clusters (Kellaway et al., 1979). The earliest manifestations of infantile spasms are subtle and are easily missed, making it difficult to identify the precise age at onset.

Recently, the National Vaccine Injury Compensation Program proposed clarification of its definition of residual seizure disorder as a seizure occurring within 72 hours of vaccination followed by two or more afebrile seizures over the next 12 months, with the seizures separated by at least 24 hours (U.S. Department of Health and Human Services, 1992). Continuing seizures in subsequent years would be anticipated. The clarifications define an afebrile seizure as one that occurs with a temperature of <101°F (rectally) or <100°F (orally). This definition is considered in the remainder of this report. When a definition for a seizure in a specific study being evaluated varies from those stated above, the definition used in the study is given.

Sensorineural Deafness

Sensorineural deafness is a form of hearing loss resulting from pathologic changes in the end organ structures within the cochlea or in the neural connections between the cochlea and the cochlear nuclei in the brainstem. This usually arises from toxic, metabolic, or ischemic events. Viral infection of the cochlea can lead to sensorineural deafness as well. It is plausible that the live attenuated viruses used in vaccines can infect the cochlea, but there is no evidence that this occurs. No population-based incidence rates were identified.


The term neuropathy as used here designates those disorders of peripheral nerve other than GBS that have, on occasion, been described in relation

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