Epileptic Syndromes

An example of an epileptic syndrome with generalized seizures is juvenile myoclonic epilepsy (JME). The seizure types are generalized tonic-clonic, absence, or myoclonic, which often occur upon awakening. The seizures begin in adolescence or early adulthood in an otherwise healthy individual. The interictal EEG reveals spike-and-wave activity at a frequency of 3.5 to 6.0 Hz, while neuroimaging is normal. Although the seizures are usually controlled with antiepileptic drugs, the condition is lifelong. A single-gene mutation has not been identified, and many investigators feel the condition likely involves multiple genes. Once diagnosed with JME, the patient can be provided specific information regarding prognosis and treatment.

Benign rolandic epilepsy, also called benign childhood epilepsy with central-temporal spikes, is a genetic disorder confined to children, which is characterized by nocturnal generalized seizures of probable focal onset and diurnal simple partial seizures arising from the lower rolandic area and an EEG pattern consisting of midtemporal–central spike foci. The characteristic features of daytime seizures include (1) somatosensory stimulation of the oral-buccal cavity, (2) speech arrest, (3) preservation of consciousness, (4) drooling, and (5) tonic or tonic-clonic activity of the face. Less often, the somatosensory sensation spreads to the face or arm. Most attacks involve the face, and arrest of speech may initiate the attack or occur during its course. Consciousness is rarely impaired during the daytime attacks, although, because of the motor involvement, the child cannot speak. Often the child’s gestures will indicate to the parents that the child is totally aware during the event. The characteristic interictal EEG abnormality is a high-amplitude, usually diphasic spike, with a prominent following slow wave. The spikes or sharp waves appear singly or in groups in the midtemporal and central (rolandic) region (C3, C4).

Infantile spasms are brief episodes of tonic flexor or extensor movements, or both, of the body and limbs. These spasms are seen in infants and young children up to 4 years of age and usually result from a severe cerebral insult before, at, or shortly after birth, or from an insult or disease process occurring within the first few months to 1 year after birth. One of the most common types of infantile spasm is characterized by forward flexion of the head and body, with the arms flung forward or outward. The EEG in infantile spasms shows a characteristic pattern called hypsarrhythmia, consisting of high-amplitude multifocal spikes and slow waves. During the spasm, the EEG shows an abrupt generalized decrement in the amplitude of the ongoing activity.

Infantile spasms are often treated with adrenocorticotropic hormone or corticosteroids. Clonazepam has been used occasionally, and in some refractory conditions, a ketogenic diet may be helpful in controlling the seizures.

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