Epilepsy in the Elderly
Posted in Management Topics in Epilepsy on 17th Jun 2013
The steady growth in the number of people over the age of 65 in industrialised countries is estimated to reach around 30% by 2030, doubling since 1985 (Figure 1). Consequently, we shall see a considerable rise in the number of elderly people with epilepsy most of whom, unlike younger patients, have multiple comorbidities. The complexity of this situation will not only impact health and social resources but also present challenges in managing the condition. This article will focus on the specific needs of the elderly which present unique challenges. These include diagnostic problems, complexities of treatment and social impact on an already vulnerable population.
The trend in the population over the age of 65 years and over in the UK, showed an increase from 15% in 1985 to 17% in 2010, that is an increase of 1.7 million people.1 Projections by the Office of National Statistics for this population group suggest they will account for 23% of the total population as illustrated in Figure 1.
The fastest growth in this group is more evident in those who are 85 and above, i.e. 0.7 million in 1985 doubling to 1.4 million and 3.5 million in 2010 and 2035 respectively, thereby accounting for 5% of the total population of the UK.1 Following a number of epidemiological studies undertaken in industrialised countries, the pattern of incidence of epilepsy has been shown to have a bi-modal distribution with the first peak in the first few years of life and the second and more striking peak after age 60.2-5 Incidence rates in the elderly of over 100 per 100,000 have been reported.6,7
The prevalence of epilepsy also increases with advancing age but to a lesser degree. Fatalities often result in those presenting with status epilepticus in acute symptomatic epilepsies.
Several studies show variability in aetiology and risk factors.6,8 These include cerebrovascular disease, neoplasms, metabolic and toxic causes, head injuries, infection, subdural haematoma, non-vascular dementias etc. Stroke however has been found to be a definite risk factor respon- sible for a high proportion of cases,2 with clinically unsuspected cerebral infarcts often demon- strated on CT scans of elderly patients with epilepsy.9 Moreover, late onset seizures carry nearly a threefold risk of subsequent stroke, when compared to age-matched controls10, a greater risk than hypercholesterolaemia or smoking, which means that the onset of seizures in this age group also necessitates the management of vascular risk factors. Seizures often have more than one cause i.e.an acute cerebral insult such as hyperglycaemia may trigger epileptic activity in pre-existing injury.
Types of epilepsy
Focal epilepsies are more commonly seen than generalised types in the elderly.6 The common epileptic syndromes in the elderly are:
• Remote symptomatic seizures e.g.due to preceding stroke.
• Acute symptomatic or provoked seizures e.g. due to acute stroke,metabolic disturbance or trauma.
• Symptomatic seizures due to progressive disease such as tumour or dementia.
• Cryptogenic i.e. unidentifiable cause but presumed to be symptomatic.
The diagnosis of epilepsy is clinical. In the elderly however, it may be difficult to differentiate seizures from possible underlying medical problems such as hypoglycaemia, syncope, confusional states etc. Another compounding problem is the lack of obtaining a reliable witness account of events especially where the elderly person lives alone or lives with a spouse with impaired memory. This may lead to misdiagnosis. For example, focal seizures are often misdiagnosed as transient cerebral ischaemic attacks, where the stereotypical epileptic symptoms have not been recognised.2 Epileptic seizures in the elderly tend to be associated with prolonged post-ictal states.11 For example, a prolonged Todd’s paresis is frequently misdiagnosed as a stroke. Epilepsia partialis continua may be misdiagnosed as a movement disorder.2 Conversely, carotid stenosis may cause transient ischaemic attacks, manifesting with recurrent focal motor activity of one arm which may be diagnosed as epilepsy. Generalised epilepsies do occasionally first present in old age,12 especially as non-convulsive status epilepticus and patients who present with none of the usual infective or metabolic causes of confusion should be screened early with EEG; a challenge in some hospitals.Studies suggest that the diagnosis of this treatable condition is generally delayed at least several days.
The risk of seizure recurrence in persons over the age of 60 was reported to be at 80% at 52 weeks with remote symptomatic seizures carrying an 85% risk at 36 months.13 An extended follow-up study reported that presence of Todd’s paresis or previous acute symptomatic seizures relating to the initial insult appeared to elevate recurrence risk.14
There is paucity of data to allow for rational therapeutic policies to be made for treatment of seizures and epilepsy in the elderly. A retrospective study showed that of the patients not treated and followed up for a year, 62% remained seizure free and 26% had less than three seizures per year.15 There are no controlled clinical studies available. Such information is necessary to make a case for treatment against epilepsy and its complications.The studies available however, report that low dose antiepileptic medication achieves seizure freedom in a majority of older people. The proportion of patients who achieved seizure freedom in a veterans’ trial of antiepileptic drug treatment in adults was higher in the older than the younger patients.16
There is also the question of what antiepileptic medication to use. The high rate of co-morbidities, accompanying co-medication and susceptibility to side effects as well as the ageing brain, suggest elderly patients may require very specific consideration with regard to choice of treatment. To add to the question of whether to treat or not is the consideration of aetiology which also forms the basis for counselling the patients and carers, a role that specialist nurses contribute to significantly. Acute symptomatic seizures are most effectively controlled by treating the underlying cause e.g.treatment of infection.
The choice of anti-epileptic drug (AED) for recurrent unprovoked seizures is an area where the few clinical trials have not kept up with changes in common practice. Certain principles can be applied. Pharmacokinetic considerations may influence drug choice or dose, especially renal or hepatic function, which are commonly altered in the elderly. Pharmacokinetic interactions, for example of enzyme inducing AED on warfarin, may determine choice and in the veterans’ study, the mean number of other drugs being taken was five. Pharmacodynamic interactions are also common, particularly hyponatraemia when carbamazepine or oxcarbazepine is combined with a thiazide diuretic and this combination should be avoided.
Commonly used AED in the elderly include carbamazepine, lamotrigine, levetiracetam and sodium valproate.2 Phenytoin was also found to be a useful first line but had more treatment failures when compared to sodium valproate in a multicentre trial, due to poor control and adverse effects.17 In spite of this, phenytoin is still used as first line by many physicians in departments of medicine for the elderly given its low cost, accessibility and ease of administration i.e. once daily dosing.18 The disadvantage of its linear kinetics makes small dose adjustments produce plasma concentrations associated with toxicity or inefficacy, which far outweigh its advantages. Lamotrigine is useful and generally well tolerated. It has a potential to cause idiosyncratic reactions. In the elderly group it may also cause insomnia and tremor. It is the only new drug where clinical trials have been conducted in the elderly (against carbamazepine) providing an evidence base, favouring its use.19 Levetiracetam’s lack of drug interactions and generally good tolerability and potentially rapid dose titration makes it widely used in the elderly although there are no specific comparative trials to support its use. Carbamazepine’s sedative effects may limit tolerability but this can be managed with a low once or twice daily starting regimen increased slowly.There is a small incidence of bone marrow suppression and hepatitis which however may be increased by age. Its antidiuretic hormone-like effect may produce fluid retention and precipitate cardiac failure in the elderly. It may also precipitate abnormal cardiac conduction in elderly patients with pre-existing cardiac disease.Sodium valproate, a non-hepatic inducing drug, is useful in the elderly who may also be receiving concomitant treatment thus would not reduce their efficacy. Its limiting adverse effects include sedation, tremor, Parkinsonism, cognitive slowing and gastrointestinal disturbances. Our preference is for lamotrigine or levetiracetam as first line in this age group.
A diagnosis of epilepsy may cause social isolation in most people, more so the elderly who may be living alone or living with another elderly physically or mentally frail spouse. The fear of falling during an epileptic seizure may cause them to confine their mobility to the household. Driving restrictions may particularly affect the elderly with comorbidities affecting their mobility. Epilepsy specialist nurses can help to minimise this level of isolation by collaboratively working with the general practitioners, community matrons, occupational therapists, family and carers. In addition to the counselling specialist nurses provide to the elderly, they can also facilitate access to day centres and safe means of transportation so that patients do not remain confined to their homes.
The burden of epilepsy in the elderly will increase with the growth of the ageing population. Its diagnosis in this age group requires consistent enquiry over and above the scanty information which may be presented by the elderly person. In selected cases, prevaricating over treatment should be seen as a cautious and safe management and families can be reassured that it is not due to indecisiveness. Once the correct diagnosis has been made, the condition is easier to bring under control than in young adults. Although evidence is limited, newer drugs should generally be considered early, because of better adverse effect and pharmaco- kinetic profiles. Management should include an epilepsy specialist nurse for this particularly vulnerable patient group.
1. Office of National Statistics 2012 Accessed 18.02.2013.
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