Epilepsy and Other Seizure Disorders
The prevalence and importance of epilepsy, recurrent unprovoked seizures, can hardly be overstated. From the epidemiologic studies of Hauser and colleagues, one may extrapolate an incidence of approximately 2 million individuals in the United States who have epilepsy and predict about 44 new cases per 100,000 persons each year. These figures are exclusive of patients in whom seizures transiently complicate febrile and other illnesses or injuries. It has also been estimated that slightly less than 1 percent of persons in the United States will have epilepsy by the age of 20 years (Hauser and Annegers). Over two-thirds of all epileptic seizures begin in childhood (most in the first year of life), and this is the period when seizures assume the widest array of forms. In the practice of pediatric neurology, epilepsy is one of the most common disorders, and the chronicity of childhood forms adds to their importance. The incidence increases again after age 60 years. For all these reasons, physicians should know something of the nature of seizure disorders and their treatment. It is notable that, in striking contrast to the many treatments available for epilepsy, as pointed out by J. Engel, 80 to 90 percent of persons with epilepsy in the developing world never receive medical attention.
The word epilepsy is derived from Greek words meaning “to seize upon” or a “taking hold of.” Our predecessors referred to it as the “falling sickness” or the “falling evil.” Although a useful medical term to denote recurrent seizures, the words epilepsy and epileptic may still have unpleasant connotations and should be used advisedly in dealing with patients. In 1870, Hughlings Jackson, the eminent British neurologist, postulated that seizures were due to “an excessive and disorderly discharge of cerebral nervous tissue on muscles.” The discharge may result in an almost instantaneous loss of consciousness, alteration of perception or impairment of psychic function, convulsive movements, disturbance of sensation, or some combination thereof.
Terminologic difficulty arises from the diversity of the clinical manifestations of seizures. The term convulsion, referring as it does to an intense paroxysm of involuntary repetitive muscular contractions, does not fully capture the range of disorders resulting from abnormal electrical discharges, or seizures, that may consist only of an alteration of sensation or consciousness. Seizure is preferable as a generic term because it embraces all paroxysmal electrical discharges of the brain, and also because it lends itself to qualification. The term motor or convulsive seizure, therefore, is not tautologic, and one may likewise speak of a sensory seizure or psychic seizure. There is also an entity of “nonconvulsive seizure” that may impair consciousness, but not manifest any abnormal convulsive movement. This represents an important and potentially treatable form of an encephalopathy or confusional state.
A first solitary seizure or brief outburst of seizures may occur during the course of many ...