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Seizures and Epilepsy

  • Andrea E. Cavanna
Chapter

Abstract

Epileptic seizures are defined as the clinical manifestations of abnormal excessive or synchronous neuronal activity in the brain: transient alterations in consciousness and/or motor control. Epilepsy is a disease characterised by an enduring predisposition to generate recurrent epileptic seizures and by the neurobiological, cognitive, psychological, and social consequences of this condition. Although approximately 1 in 20 people may have a seizure during their lifetime, the prevalence of epilepsy is considerably lower, being around 0.5–1% for the general population. The cornerstone of the seizure classification system is the determination of whether the initial manifestations of the seizure are focal or generalised. Additionally, focal seizures are sub-grouped as those with motor and non-motor manifestations at the onset. Finally, the behavioural assessment of consciousness (operationally defined as the patient’s awareness of self and environment during a seizure) may be included in the classification of focal seizure types. Behavioural symptoms are commonly reported by patients with epilepsy, and the neuropsychiatric aspects of epilepsy can be classified according to their temporal relationship to epileptic seizures as ‘interictal’ and ‘ictal’ psychiatric disorders.

Keywords

Awareness Classification Consciousness Epilepsy Seizure 

Epileptic seizures are defined as the clinical manifestations of abnormal, excessive or synchronous neuronal activity in the brain. During epileptic seizures, patients present with transient and self-limiting clinical episodes usually involving alterations in consciousness and/or motor control. Epilepsy is a disease characterised by an enduring predisposition to generate recurrent epileptic seizures and by the neurobiological, cognitive, psychological, and social consequences of this condition. More specifically, epilepsy can be diagnosed when any of the following conditions are met: (1) at least two unprovoked (or reflex) seizures occurring greater than 24 hours apart or (2) one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the following 10 years. Conversely, a diagnosis of an epilepsy syndrome is considered to be resolved for patients who remained seizure-free for the preceding 10 years, without antiepileptic drugs for the preceding 5 years. Although approximately 1 in 20 people may have a seizure during their lifetime, the prevalence of epilepsy is considerably less, being around 0.5–1% for the general population.

Standardised classification systems of seizures and epilepsy were developed by the International League Against Epilepsy (ILAE) in 1981 and 1989, respectively. In 2017, the International League Against Epilepsy Commission for Classification and Terminology published a revised classification of seizure types. The cornerstone of the seizure classification system is the determination of whether the initial manifestations of the seizure are focal or generalised. In case the seizure onset is missed or obscured, the seizure is classified as ‘of unknown onset’. Additionally, focal seizures are sub-grouped as those with motor and non-motor manifestations at the onset. Finally, the behavioural assessment of consciousness (operationally defined as the patient’s awareness of self and environment during a seizure) may be included in the classification of focal seizure types. Impaired awareness during any part of the seizure renders it a ‘focal impaired awareness seizure’, which corresponds to the prior definition of ‘complex partial seizure’. Conversely, a ‘focal aware seizure’ corresponds to a ‘simple partial seizure’ in the nomenclature of the previous classification system. Consciousness is not a classifier for generalised-onset seizures, because these seizures are characterised by the involvement of both hemispheres at onset and therefore invariably present with impaired awareness. Generalised seizures are divided into motor and non-motor (absence) seizures. Further subdivisions of motor generalised seizures refer to the type of motor manifestations: tonic-clonic (classical convulsions or grand mal seizures) or other motor manifestations (clonic only, tonic only, myoclonic, atonic, etc.). Non-motor seizures with focal onset can have autonomic, behavioural, cognitive, emotional, or sensory manifestations, whereas non-motor seizures with generalised-onset correspond to ‘absence seizures’. Absence seizures have long been known to be associated with regular 3 Hz spike and slow-wave activity on electroencephalography (EEG). A simplified version of the currently adopted classification scheme for epileptic seizures is presented in Fig. 12.1.
Fig. 12.1

Simplified classification scheme of epileptic seizures

The classification of the epilepsies is essentially one of syndromes. Since there are no epilepsy syndromes currently approved by the ILAE, the terminology in use often reflects historical syndromic concepts (e.g., ‘psychomotor epilepsy’ or mesial temporal lobe epilepsy, nocturnal frontal lobe epilepsy, ‘Janz syndrome’ or juvenile myoclonic epilepsy, ‘Lennox-Gastaut syndrome’, ‘West syndrome’, etc.).

Although the long-standing relationship between epilepsy and psychiatry has been recognised since at least the ancient Greek tradition, it is only in the twentieth century that the neuropsychiatric aspects of chronic epilepsy have become the focus of dedicated research. Behavioural symptoms are commonly reported in the context of epilepsy, and it is estimated that between 30 and 50% of patients with epilepsy have behavioural co-morbidities. This figure is likely to be higher in the subgroup of patients with intractable focal impaired awareness seizures. A quick look at the number of international scientific publications on the behavioural aspects of epilepsy provides further evidence in support of this scenario (Table 12.1). For example, the number of publications on behavioural symptoms accounts for about 20% of the total number of publications on the most common types of epilepsy (focal epileptic syndromes—temporal lobe epilepsy and frontal lobe epilepsy—and generalised idiopathic epilepsy). Moreover, a percentage between 10 and 15% of the total number of publications on each epileptic syndrome focuses on affective symptoms.
Table 12.1

Articles focusing on the behavioural aspects of epilepsy indexed in the PubMed database (numbers of review articles in brackets)

 

Epilepsy (all types)

Temporal lobe epilepsy

Frontal lobe epilepsy

Generalised epilepsy

Affective symptoms

18,181

(3458)

2724

(371)

804

(111)

1952

(300)

Anxiety symptoms

3614

(803)

490

(71)

114

(24)

332

(49)

Psychotic symptoms

2694

(586)

481

(63)

156

(25)

261

(57)

Impulsivity

1847

(389)

346

(49)

96

(12)

230

(57)

Total publications

149,410

(20,857)

22,548

(2399)

6380

(633)

14,023

(1896)

The traditional approach to the classification of behavioural symptoms in epilepsy follows the temporal relationship to the epileptic seizure itself. Ictal (and postictal) psychiatric disorders are directly related to the seizure and have an episodic pattern, whereas interictal disorders are unrelated in time to the seizure and tend to have a chronic course (Table 12.2).
Table 12.2

Classification of main psychiatric disorders in epilepsy

Temporal correlation with epileptic seizure

Psychiatric disorder

Interictal

Affective disorders

Anxiety disorders

Schizophrenia-like psychosis of epilepsy

Personality disorders

Ictal and postictal

Ictal alterations in behaviour and consciousness (aura)

Postictal psychosis

The following chapters focus on the neuropsychiatric aspects of epilepsy, encompassing both interictal and ictal psychiatric disorders. Chapter  13 is dedicated to common chronic conditions such as affective and anxiety disorders in patients with epilepsy, followed by the so-called schizophrenia-like psychosis of epilepsy, which is a relatively less frequent but arguably more severe behavioural condition. Both the rare phenomenon of alternative psychosis associated with forced normalisation and the controversial issue of temporal lobe epilepsy personality syndrome (Gastaut-Geschwind syndrome) are briefly addressed. This discussion is followed by a chapter covering ictal acute behavioural changes, with focus on seizure-induced alterations of consciousness and postictal psychosis. These observations highlight the role of temporal lobe structures in ictal alterations of the contents of consciousness (e.g., ictal fear) and the inherent implications for our understanding of the neural correlates of consciousness, including ‘epileptic qualia’. Part 3 closes with an introduction to psychogenic nonepileptic attack disorder, a condition characterised by episodic functional symptoms manifesting as convulsions and/or unresponsiveness and not associated with abnormal electrical activity in the brain.

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Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  • Andrea E. Cavanna
    • 1
  1. 1.Dept of NeuropsychiatryUniversity of BirminghamBirminghamUnited Kingdom

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