Epilepsy Simplified

Leach, John P., O'Dwyer, Rebecca

• Publisher: tfm Publishing Ltd
• Year: 2011
• ISBN:
  9781908986603
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

Simplicity is an underrated virtue; where information is vital, it should be possible to put it across in a way that is easy to understand and remember. Epilepsy is a common condition which has been recognised since the beginning of history, and as the opportunities for diagnosis and effective treatment have increased, it becomes more important that health professionals have a working knowledge of how epilepsy interacts with their own area of expertise. The interactions between all aspects of medicine and epilepsy should motivate all to do their best to learn about management of all stages of the disease, from first seizure through to status epilepticus. This is recognition that providing a diagnosis of epilepsy has more than medical implications, and in fact it is safe to say that there are few aspects of modern life that will remain untouched by such a diagnosis and consequent treatment. At some point, discussions will be required around the issues of fertility, job prospects, driving issues, family safety, childcare, travel, life insurance, diet, and sports participation. This book, has been produced by Dr Becky O'Dwyer and Dr John Paul Leach, recognised experts in epilepsy from opposite sides of the Atlantic. They have tried to make the key concepts of epilepsy's cause, prognosis and treatment accessible to all in this compact format, providing information for clinicians and permitting informed choice for patients and their families.

Chapter 1

Definition and epidemiology of epilepsy

What is epilepsy?

Definitions

Epilepsy is a very variable disorder. To help form an image in your mind, it may be helpful to define various seizure manifestations and aspects of the disease. Things might at first seem rather complex when we start by saying that while all patients with epilepsy experience seizures at some point, not all patients with seizures have epilepsy. Bear with us, it’ll be less complex than you think!

Epileptic

This is a word which shows that something is caused by or related to epilepsy. Given the stigma, it has become politically incorrect to use it as a single word to describe a patient. Actually while I usually find PC phrases jarring, I completely agree with this - it should go the way of other terms which have evolved a derogatory undertone (e.g. ‘mental’, ‘cretin’, ‘banker’). The acceptable term is ‘patient with epilepsy’.

Epileptic seizure

An epileptic seizure is a clinical manifestation resulting from abnormal and excessive electrical discharges in a set of neurones within the brain. This may involve alteration of consciousness, alongside motor, sensory, autonomic or psychic events, that can be perceived by the patient or an observer. In other words, seizures cause signs, or symptoms, or both.

Acute symptomatic seizure

Acute symptomatic seizures are an immediate response to any form of brain insult, whether traumatic, systemic, toxic or metabolic in nature. They may be referred to in the literature as a ‘provoked seizure’ or ‘situation-related seizure’. Evidence would suggest that having an acute symptomatic seizure does not lead to an increased risk of future spontaneous seizures.

Unprovoked single seizure

An unprovoked single seizure is any seizure (or cluster of seizures occurring within 24 hours), in a person older than one month of age and in the absence of any precipitating factors or possible responsible clinical condition. After a single event (see section on single seizures later) only around half of patients will have a spontaneous recurrence. There are therefore good prognostic and therapeutic reasons for separating out patients having a single seizure from those with a diagnosis of epilepsy. Unprovoked seizures may result from a static brain injury (e.g. cerebral ischaemia, trauma) or a progressive (not acute) injury (e.g. tumour, degenerative disorder). There is an increased risk of recurrence of a single seizure in patients with an underlying brain injury.

Provoked seizure

A seizure with a specific and isolated cause (e.g. immediate aftermath of a head injury, stroke, alcohol withdrawal).

Epilepsy

Now we get to the easy part. Once there have been two or more unprovoked seizures (see above) then the patient is deemed to have epilepsy. Because the prognosis of recurrence differs in patients who have had febrile seizures and neonatal seizures (<1 month of age), these two groups are excluded from this definition.

Epileptic syndrome

Syndromic diagnosis of epilepsy (see later section) tries to group types of epilepsy according to type of seizures and source of discharges. For example, if the epilepsy arises from the frontal lobes then the epilepsy syndrome is said to be a frontal lobe epilepsy. Discussion will follow later on the classification of epilepsy and seizures (bet you just can’t wait!).

Seizure semiology

The symptoms and signs noted directly before, during and directly after a seizure.

Status epilepticus

A single epileptic seizure of longer than 30 minutes or a cluster of epileptic seizures lasting for 30 minutes or longer during which the patient has not regained their baseline level of functioning.

Ictal

Ictal is an adjective describing the period of time during any attack (or for the purpose of this book usually an epileptic seizure), e.g. post-ictal drowsiness, ictal spitting.

Interictal

Interictal is an adjective describing the periods of time in between epileptic seizures.

Epidemiology of epilepsy

Epilepsy is a common disease that occurs worldwide and affects patients of any age. It is estimated that the annual incidence of epilepsy is approximately 80 cases per 100,000 people, with development of chronic epilepsy resulting in a prevalence of around 0.5% (Table 1). The incidence varies with age, the majority of newly diagnosed patients being at the extremes (either under 2 years of age or older than 65 years). Annually, about 20 people per 100,000 will have an isolated seizure. The estimated risk of developing epilepsy over a lifetime (the ‘cumulative incidence’) ranges from 3 and 5%.

A higher prevalence of epilepsy is seen in underdeveloped areas, especially where cysticercosis is endemic. Similarly, epilepsy is more common in lower socio-economic classes, perhaps due to poorer perinatal care, nutrition and hygiene, in addition to exposure to a greater risk of brain injury and cerebral infection. There is no marked gender preference, but males have a slightly higher risk of being diagnosed with epilepsy.

Within 5 years of onset of seizures, 50-60% of patients will enter a long period of remission on starting treatment, many having long-term control. Up to 30% of patients will eventually develop medically refractory epilepsy despite multiple anticonvulsant medication trials. Given the need for ongoing monitoring and possible trials of further drug combinations, this 30% forms a disproportionately large number of the cohort ...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Contents
• Preface
• Glossary
• About the authors
• Acknowledgements
• Thought for the book
• First aid for seizures
• Chapter 1: Definition and epidemiology of epilepsy
• Chapter 2: Aetiology and pathophysiology of epilepsy
• Chapter 3: General history taking
• Chapter 4: Differential diagnosis of epilepsy
• Chapter 5: Classification of epilepsy
• Chapter 6: Seizure types
• Chapter 7: Diagnosis of epilepsy
• Chapter 8: Anti-epileptic drugs for epilepsy
• Chapter 9: Future developments in the treatment of epilepsy
• Chapter 10: When things go well – monotherapy and withdrawal
• Chapter 11: When things are not going well – polypharmacy, surgery and status epilepticus
• Chapter 12: Epilepsy at extremes of age
• Chapter 13: Specific situations
• Chapter 14: Common questions