Seizures in old age

Summarized by Robert W. Griffith, MD
June 7, 2000 (Reviewed: December 8, 2002)

Introduction

Most physicians are unaware that old age is the most common time to develop seizures. A population study done in the United Kingdom showed the rise in both incidence (number of new cases in a given time/population) and prevalence (number of cases at one time in a population) with age:

	Annual Incidence (per 1,000)	Prevalence (per 1,000)
General population	69	9.0
60 - 69 years	76	10.9
70 _ 79 years	147	12.0
80 years and above	159	13.1

The diagnosis and treatment of epilepsy in the elderly present special problems, and these have been reviewed in the article summarized here.

Etiology

Idiopathic epilepsy is commonly diagnosed in early life. In the elderly, it accounts for only about 25% of new cases. For the remaining 75%, there is usually a precipitating cause. If the seizure occurs within a week of the triggering event it is categorized as "acute symptomatic". Those occurring more than a week after the precipitating factor are termed "remote symptomatic" seizures.

Common causes of acute symptomatic seizures include: cerebral thrombosis, cerebral hemorrhage, subarachnoid hemorrhage, head injury, subdural hematoma and metabolic disturbances (including alcohol withdrawal and drug-related). Remote symptomatic seizures can be caused by a previous cerebral infarction, cerebrovascular disease, head injury, cerebral atrophy, cerebral tumor, and non-vascular dementia.

Cerebrovascular disease is the most common pathology ultimately responsible for seizures in the elderly - it is found in over 1/3 of cases of status epilepticus in later life. Obviously hemorrhage or thrombosis can trigger seizures, but so can local ischemia and cytotoxicity.

Head trauma is relatively common in old age, and is more likely to result in post-traumatic epilepsy than in young subjects. Drug-induced seizures are more likely in cases of polypharmacy, overdosage, parenteral administration and coexisting illness. The list of drugs that have been associated with seizures is extremely long, and covers nearly all drug classes.

Management

As with younger patients, a reliable history and an eyewitness account of the seizure is often more valuable than an abnormal investigational finding. Coexisting disorders can confuse the issue, and the differential diagnosis should include: cardiac arrhythmias, hypoglycemia and non-ketotic hyperglycemia, vasovagal states and postural hypotension, and adverse drug effects.

Because of the possibility, indeed likelihood, of confusion from coexisting disorders, investigation of seizures must be extensive: ECG, carotid and basilar ultrasound, orthostatic hypotension testing (preferably using a tilt table, thyroid activity tests, and full hematological and blood chemistry work-up.

Neuroimaging (magnetic resonance imaging is preferred over computerized tomography) is more helpful than electroencephalography (EEG) in detecting causative intracranial pathology. In the elderly, 12-38% of healthy persons develop EEG abnormalities, whereas the tracings are often unhelpful in diagnosing seizures in this age group.

Complete control of seizures, without diminishing the quality of life, is the goal of treatment. The primary care (family) physician should make the initial diagnosis and refer the patient to a specialist center for appropriate investigations, full diagnosis and, eventually, drug treatment. From an early stage, education of the patient, spouse, and children is essential, in order to obtain their cooperation in starting and maintaining the treatment regimen. Life-long therapy will be needed to prevent further seizures, and a team of advisors (family physician, nurse, health visitor, social worker) may be appropriate.

There are numerous anti-epileptic drugs available, but their use in the elderly is complicated by age-related changes in pharmacokinetics that can affect the amount absorbed, the time taken for the drug to reach peak activity, and the rate at which it is excreted. Unfortunately, well-conducted studies of anti-epileptic drugs in older patients are rare. It is therefore often advisable to select well-tried, older, drugs. Carbamazepine is safe and effective in the elderly, as is sodium valproate. Of the newer drugs, both lamotrigine and gabapentin are popular. Oxcarbazepine represents an "improved" carbamazepine (good efficacy and similar side-effects, combined with a more selective enzyme-inducing profile).

Drugs should be dosed carefully in elderly epileptics - smaller doses are needed than in young adults - but, with care, complete control of seizures can be expected in about 70% of patients. Add-on combinations may permit improved control with low doses of each drug.

Elderly people first diagnosed with epilepsy can experience shock and dismay. The condition carries a stigma that may lead to withdrawal, loss of self-confidence and independence, and a general decline in well-being. Anxious relatives can be over-protective, and there is the additional burden of surrender of one's driving license.

Increased mortality rates reported in older persons with epilepsy probably represent the effects of underlying diseases. If seizures cannot be controlled with medication, there will be further risk of falls, burns, fractures, etc.

This summary is not able to give due justice to the valuable information contained in the original review. The important points cover the need for family physicians to be aware of the increased incidence of seizures in the elderly and the likely causes, and their responsibility to get patients to a suitable specialist center for evaluation and treatment. Anti-epileptic drugs should be started only after a firm diagnosis is made, when patients and their relatives are convinced of the need for probable lifetime treatment. A coordinated approach will ensure the likelihood of a successful outcome.

Source

• Epilepsy in elderly people. LJ. Stephen, MJ.  Brodie, Lancet 2000, , vol. 355, pp. 1441--1446

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