The Clinical Psychologist's Handbook of Epilepsy

Assessment and Management

Christine Cull, Laura H. Goldstein, Christine Cull, Laura H. Goldstein

• Publisher: Routledge
• Year: 2002
• Topic: Psychology
• eBook ISBN:
  9781134791453
• Subtopic: Neurology
• Index: Psychology

Psychological techniques have a major role to play in the treatment and management of epilepsy. The Clinical Psychologist's Handbook of Epilepsy is the first comprehensive reference text written specifically from a psychological angle.
A team of experts review the latest research and give practical advice for the clinician in areas including neuropsychological assessment, the impact of anti-epileptic medication, behaviour problems in children with epilepsy, and the impact of epilepsy in people with learning disabilities.
A practical handbook for all psychologists working in the area, whether new to the field or more experienced, The Clinical Psychologist's Handbook of Epilepsy will also provide a useful resource for research.

Chapter 1
An introduction to epilepsy
Christine Cull and Laura H.Goldstein

WHAT IS EPILEPSY?

Epilepsy is . . .

a chronic disorder characterised by recurrent seizures

(Gastaut 1973)

and a seizure is . . .

an occasional, an excessive and a disorderly discharge of nerve tissue

(Hughlings Jackson in Taylor 1958)

that is, an episode of altered behaviour and/or consciousness, which can take many forms, but which results from an abnormal electrical paroxysmal discharge in cerebral neurones. Types of epileptic seizures will be described later in this chapter but, a clinical diagnosis of epilepsy is made if two epileptic seizures occur within a two-year period.

EPIDEMIOLOGY

Epilepsy is a common neurological disorder, occurring in 5:1000 children (Cowan et al. 1989) and in 4–7:1000 adults (Hauser and Annegers 1993), such that in the UK it has been estimated that there are approximately 350,000 people with a diagnosis of epilepsy (Brown and Betts 1994). The prevalence of epilepsy is reported to be ten times that of multiple sclerosis and a hundred times that of motor neurone disease (Brown et al. 1993).

New cases reported each year are in the region of 20–70 per 100,000 (Hauser and Annegers 1993), the highest rates occurring in infants and young children and in the elderly (Brown et al. 1993). The incidence is consistently found to be higher in males than females, although in most studies the difference fails to reach statistical significance (Hauser and Annegers 1993).

CAUSES OF EPILEPSY

Everybody has the potential to have an epileptic seizure. When considering the aetiology of seizures, Lishman (1987) emphasises however that epilepsy must be thought of as a symptom rather than a disease. He also indicates that for many people the cause of the disorder may never be identified. The proportion of cases of unknown aetiology may account for as many as two-thirds of cases (see Lishman 1987). He indicates that the majority of such seizures are generalised (either absence or tonicclonic) in nature, and that in most cases the presence of a focal component to the seizures will indicate the existence of a discrete structural brain lesion. In addition, an hereditary component is found more commonly for seizures of unknown origin than for seizures that occur in the presence of readily identifiable brain lesions.

Where causes can be identified, they may be varied in nature. Lishman (1987) reviews these causes, and categorises them as seizures due to birth injury or congenital malformations, due to brain damage, infections, cerebrovascular disease, tumours, neurodegenerative disorders, drugs or toxins, or metabolic disorders. Chadwick (1994) distinguishes between acute symptomatic seizures that are the result of some metabolic disorder or cerebral insult, and remote symptomatic seizures that reflect some form of persisting brain damage. Hopkins (1987), on the other hand, considered two main classes of aetiology— predisposing and precipitating factors—and this subdivision will be used here.

Predisposing factors

When considering predisposing factors, it is important to remember that these may not be independent of each other. Thus, a genetic predisposition towards epilepsy may involve either the inheritance of a convulsive threshold, or of a condition associated with epilepsy (see Anderson and Hauser 1993). Lishman (1987) indicates that family loadings seem to be more marked with certain types of seizures, but he cautions that the potential to have an epileptic seizure is present throughout the population, given the right precipitating circumstances.

Developmental brain abnormalities that predispose to seizures may or may not be inherited. Porencephaly, microgyria (and other abnormalities of the cortex), tuberous sclerosis and arteriovenous malformations are other congenital malformations that may be associated with the development of epilepsy. In addition, the person may have acquired structural brain abnormalities that then predispose to epilepsy. With respect to epilepsy arising from birth injury, Lishman (1987) indicates that pregnancy and delivery complications may produce brain damage and lead to epilepsy. Particularly relevant here is damage that produces anoxia or cerebral haemorrhage. Illnesses early in infancy (e.g. cardiorespiratory disorders, infections or metabolic disorders) may also produce seizures. The occurrence of febrile convulsions, possibly with status epilepticus, may give rise to anoxic damage and the formation of scar tissue. This so-called ‘mesial temporal sclerosis’, which consists of gliosis of mesial temporal lobe structures, is commonly found in patients with temporal lobe epilepsy. Whilst this was initially thought to occur unilaterally in most cases, data revealing the more frequent bilateral presence of abnormality is now appearing (Incisa della Rochetta et al. 1995).

In terms of post-traumatic epilepsy, head injury carries a high risk for the subsequent development of seizures. In cases of closed head injury, the underlying neuropathology may include the formation of scar tissue (gliosis) with focal cerebral atrophy. The incidence of epilepsy will be about 5 per cent once the immediately post-traumatic seizures have been excluded (Jennett 1975). Post-traumatic seizures may not appear for several years after injury even though more than half of those going on to develop epilepsy after head injury will do so in the first year postinjury. Where there has been an open head injury, with skull penetration or fracture, there is a much higher incidence of post-traumatic epilepsy (e.g. Russell and Whitty 1952). Post-traumatic seizures may prove difficult to treat, and have important implications for rehabilitation following head injury. Their development must be considered when estimating compensation following head injury.

Certain infections of the central nervous system are likely to be associated with the development of epilepsy. Thus encephalitis or cerebral abscesses are more likely to lead to the development of epilepsy than is meningitis (Lishman 1987). In certain parts of the world, parasitic cysts play an important role. Epilepsy may also develop as a consequence of subtle brain involvement during childhood mumps or whooping cough, although this may be hard to determine in individual cases. In older patients, neurosyphilis should be ruled out as a cause of seizures.

Again, in older patients, cerebral arteriosclerosis and episodes of hypertensive encephalopathy may be important aetiological factors. Lishman (1987) indicates that a cerebral embolus is more likely to lead to epilepsy than are either a thrombosis or a cerebral haemorrhage; however, any cerebral infarct may provide a focus for the subsequent development of seizures. With ageing, the increased incidence of dementia may also be accompanied by the development of epilepsy, and seizures may occur in 25–33 per cent of cases of Alzheimer’s disease and in Huntington’s and Creutzfeldt-Jakob disease (see Shorvon 1988). Demyelinating neurodegenerative disorders such as multiple sclerosis may accompany seizure onset in adults, whereas in children degenerative disorders such as tuberous sclerosis may be causative. The development of seizures in a previously healthy adult may reveal the existence of a brain tumour. Sumner (1969) indicated that in 20 per cent of cases of cerebral tumour, the first symptom may be the onset of seizures.

Precipitating factors

A number of factors can be shown to precipitate seizures. Many of these are due to toxic conditions or metabolic disturbances, with an interaction between these. Thus, in addition to alcohol and rapid withdrawal from other drugs, Lishman (1987) notes the wide range of substances that may be associated with seizures. These include barbiturates, amphetamines, ergot alkaloids and steroids, as well as exposure to lead and the chlorinated hydrocarbons found in some pesticides. In addition, certain antipsychotic and antidepressant agents may lower seizure thresholds, thus making them more likely to occur.

A wide range of metabolic causes have been found for seizures. These may include porphyria, and occasionally hypoglycaemia, as well as uraemia, hypernatremia and hypercalcaemia. Electrolyte disturbances, such as those occurring in eclampsia may also be associated with seizure occurrence.

Certain external stimuli may precipitate seizures. Thus, there are accounts of reading, music, flashing lights, TV screens, loud sounds and other such events precipitating seizures (see Chapter 7 for further discussion of so-called reflex epilepsies).

Changes in the sleep–wake cycle have also been shown to precipitate seizures, as has sleep deprivation, and some seizures occur on waking. For seizures which occur in sleep and arise from the frontal lobes, the precipitating factor is the transition between different stages of sleep. Rapid alterations in arousal level in the waking state may also be associated with seizure occurrence (see Chapter 7).

In some women with epilepsy, seizure occurrence is related to the menstrual cycle. So-called catamenial epilepsy, where there is an increase in seizure frequency pre- or perimenstrually in the majority of menstrual cycles, has been shown to occur in anything from 9–72 per cent of women with drug resistant epilepsy (Crawford 1991).

Other precipitating factors may take the form of illnesses and intercurrent infections. The possibility that psychological factors may influence seizure occurrence will be considered in Chapter 7.

Overall in terms of the epidemiology related to aetiology, Sander et al. (1990) found that in newly diagnosed patients with seizures, tumours were a rare cause of seizures in people younger than 30 years of age, accounting for only 1 per cent of the sample studied; however in adults between the ages of 50 to 59 years, 19 per cent of cases were attributed to the presence of a tumour. Vascular disease accounted for 49 per cent of cases of epilepsy in elderly individuals. In general, cerebral infection was the cause in 2 per cent of cases and traumatic brain injury was found in 3 per cent of the sample. Alcohol was the most likely single cause of what Chadwick (1994) termed acute symptomatic seizures, accounting for 6 per cent of these, with the highest incidence occurring in adults aged between 30 and 39 years old.

PROGNOSIS

Chadwick (1994) reviewed a number of studies that have considered prognostic indices for seizure remission. Prognostic factors may include age at onset of epilepsy, duration of epilepsy before the onset of treatment, seizure type and aetiology and although Chadwick indicated that none of the studies to date permit adequate quantification of the relative weights that each of these factors may play in overall prognosis, age at onset of seizures seems to be the most important factor, with seizures beginning in the first year of life carrying a poor prognosis. In addition, the absence of early brain damage and the absence of evidence of generalised seizure activity are positive indications of good outcome. The interested reader is referred to his useful paper for more details.

It is important to note that a diagnosis of epilepsy carries with it increased risk of mortality, perhaps some two or three times higher than expected for the general population (Chadwick 1994). The risk is highest in the first year of life, and in individuals with tonic-clonic and frequently occurring seizures. Sudden unexpected death in people with epilepsy is a matter of concern as is accidental death due to drowning, with patients with epilepsy needing to take precautions over bathing and swimming arrangements. Accidents involving falling or burns as a result of seizures are problematic but rarely result in death.

CLASSIFICATION OF SEIZURE DISORDERS

Different classification systems of seizure disorders exist, focusing either on the type of seizure or on the type of epilepsy. One is therefore symptombased, while the other is disorder-based.

The classification of seizures by the International League Against Epilepsy (ILAE) ignores underlying anatomical features of seizures and does not take into account age and gender in its seizure classification (see Neppe and Tucker 1992). It broadly divides seizures into partial (simple and complex), generalised and unclassified epileptic seizures. For a fuller discussion of seizure classification, see Dreifuss and Henriksen (1992) and Chadwick (1994).

Partial seizures

Partial seizures are subdivided into simple and complex partial seizure types. In simple partial seizures there is no alteration of consciousness. Seizures begin in a localised brain area with the sensations evoked dependent upon the part of the brain that is involved. Simple partial seizures are subdivided into motor (any part of the motor cortex can be involved), somatosensory (with sensory, somatosensory, gustatory or vertiginous symptoms), autonomic (with vomiting, flushing, sweating) and psychic (dysphasia, dysmnesia, d&j' vu, jamais vu) seizures.

In complex partial seizures, there is a characteristic alteration of consciousness, and the person demonstrates automatic behaviour (automatisms), which takes the form of more or less co-ordinated involuntary activity occurring either during the seizure or immediately after it, and for which the person is usually amnesic. Automatic behaviour may take the form of eating actions (chewing, swallowing), gestures, ambulation and verbal utterances. Complex partial seizures most commonly arise from the mesial temporal lobe structures, although approximately one-third of such seizures have their origin in the frontal lobes. ...

Table of contents

• COVER PAGE
• TITLE PAGE
• COPYRIGHT PAGE
• ILLUSTRATIONS
• CONTRIBUTORS
• PREFACE
• ACKNOWLEDGEMENTS
• INTRODUCTION
• CHAPTER 1: AN INTRODUCTION TO EPILEPSY
• CHAPTER 2: NEUROPSYCHOLOGICAL ASSESSMENT
• CHAPTER 3: EPILEPSY AND MEMORY
• CHAPTER 4: ASSESSMENT FOR SURGERY
• CHAPTER 5: THE ROLE OF ANTI-EPILEPTIC DRUGS: THEIR IMPACT ON COGNITIVE FUNCTION AND BEHAVIOUR
• CHAPTER 6: PSYCHOLOGICAL RESPONSES TO EPILEPSY: THEIR DEVELOPMENT, PROGNOSIS AND TREATMENT
• CHAPTER 7: PSYCHOLOGICAL CONTROL OF SEIZURES
• CHAPTER 8: QUALITY OF LIFE
• CHAPTER 9: NEUROPSYCHOLOGICAL AND COGNITIVE ASSESSMENT OF CHILDREN WITH EPILEPSY
• CHAPTER 10: ASSESSMENT AND MANAGEMENT OF BEHAVIOUR PROBLEMS IN CHILDREN
• CHAPTER 11: EPILEPSY AND LEARNING DISABILITIES
• CHAPTER 12: THE WAY FORWARD
• APPENDIX