Page 422 - ILAE_Lectures_2015

Chapter 43

Epilepsy and seizures in geriatric practice

J.W. SANDER

UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, Queen
Square, London, and Epilepsy Society, Chalfont St Peter, Buckinghamshire

Introduction

Epilepsy is the third most common neurological disorder in old age after dementia and stroke.
With the elderly population (particularly those over 75 years) rapidly increasing, epilepsy in
old age should be regarded as a significant public health issue as well as an important clinical
problem.

Epidemiology

The incidence of epilepsy follows a bi-modal distribution. The first peak is in the first few
years of life whilst a second and more pronounced peak is in those over 60 years old. Indeed,
the elderly are now the group with the highest incidence of epilepsy in the general
population1. Incidence rates of over 100 per 100,000 for epilepsy in people over 60 years old
have been reported2. The incidence of acute symptomatic or provoked seizures also rises
significantly in older persons3 and the prevalence of epilepsy increases with advancing age,
although to a lesser degree.

Aetiology and risk factors

A number of studies show considerable variability in the causes and risk factors for epilepsy4-
6. The most frequently reported risk factor is cerebrovascular disease (3068%), though
stroke is responsible for an even higher proportion of cases (around 75%) in which a definite
risk factor is identified7. In elderly people with epilepsy, clinically unsuspected cerebral
infarcts are often demonstrable on scanning8.

Tumours are a less frequent cause of seizures (around 1015%)5,7 and are usually metastatic
or aggressive gliomas, though the epidemiological data are inadequate. Meningiomas may
mimic transient cerebral ischaemia. Metabolic and toxic causes (e.g. drugs or alcohol) and
cerebral hypoxia secondary to the many causes of syncope in old age account for around 10%
of all seizures, and a higher proportion of acute symptomatic seizures, in old age. Seizures
often have a mixed aetiology, and a minor metabolic insult may trigger epileptic discharges
from a pre-existent focus of injury. Other causes of seizures include head injury, infection,
subdural haematoma and non-vascular dementia.

Seizure types and syndrome classification

Focal seizures occur more frequently than generalised seizures (of any type) in old age5 but
generalised seizure disorders do occasionally first manifest themselves in this age group9.
Thus EEG recording in this age group may be required to classify seizure type, particularly
if there is the possibility of a generalised seizure disorder. EEG may also be required at times
if focal onset is suspected when secondary generalisation is the only clinical manifestation.