Chapter 10: Complex Partial Seizures of Extratemporal Origin

Introduction

Many seizures arise from frontal, parietal, and occipital lobes, and these are collectively referred to as extratemporal seizures. They are commonly encountered, and merit recognition because some extratemporal seizures reflect the presence of specific syndromes. Some types are inherited, others are acquired, and both medical and surgical treatments may be used. This chapter will review the features of extratemporal seizures.

Epidemiology

The prevalence of extratemporal complex partial seizures is not known due to limited epidemiologic data. Data exist for the epidemiology of extratemporal epilepsies, but the seizure type of those within the series is not included. In a prospective community-based study of 160 patients with localization related epilepsy, 36 (22.5%) were frontal, 43 (27%) were temporal, 9 (5.6%) were frontotemporal, 10 (6.2%) were parietal, 52 (32.5%) were central, and 10 (6.2%) were occipital.¹ In the Montreal surgical series, temporal lobe epilepsy represented 56%, frontal lobe 18%, central or sensorimotor 7%, parietal 6%, and occipital 1% of 2177 patients,² but this does not reflect prevalence. Parietal and occipital lobe seizures account for about 6% and 5-10%, respectively, of surgically treated epilepsy patients.^3–5 Seizures arising from frontal, parietal, and occipital lobes may start at any age, with both genders equally affected.

Associated Epilepsy Syndromes and the Syndrome's Natural History

The International League Against Epilepsy has recognized three idiopathic benign epilepsies of childhood.⁶ The most common idiopathic benign epilepsy in childhood is benign childhood epilepsy with centrotemporal spikes (BECTS), or rolandic epilepsy, first described by Loiseau and Beaussant in 1958.⁷ This condition has a 15% prevalence rate among the epilepsies in the 1-to-15-year age group and a male predominance (∼60% male). The defining features are clinical manifestations emanating from the lower part of the pre- or postcentral gyri, onset between 3 and 13 years of age, centrotemporal spikes, and normal neurologic examination and developmental and cognitive skills. The ictal behavior consists of simple partial seizures with hemifacial or oropharyngeal sensorimotor symptoms or speech arrest; nighttime seizures may generalize secondarily. The interictal EEG shows centrotemporal spikes, high-amplitude sharp and slow wave complexes at C3 and C4, which are commonly bilateral and occur independently and increase in rate of occurrence during sleep. The spikes have a horizontal dipole with maximum electronegativity in centrotemporal regions and positivity in the frontal regions.⁸ Video-electroencephalographic monitoring (VEM) is rarely indicated in these children. Benign childhood epilepsy with centrotemporal spikes is genetically determined but heterogeneous in its manifestations. There is evidence for linkage to a region on chromosome 15q14.⁹ The prognosis is excellent, with remission within 2 to 4 years of onset and before age 16. The risk of having recurrent seizures after remission is 1 to 3%, similar to that of the normal population.

The benign occipital epilepsies include early- and late-onset forms. The late-onset type described by Gastaut and idiopathic photosensitive ...