Epilepsy in the Elderly

Ann Johnston; Phil EM Smith

Disclosures

Expert Rev Neurother. 2010;10(12):1899-1910. 

In This Article

Causes

Cerebrovascular disease, primary neurodegenerative disorders, brain tumors and traumatic head injury, are the most commonly identified etiologies in patients with late-onset epilepsy.[13] However, the underlying cause of epilepsy cannot be identified in up to 50% of elderly people (termed 'cryptogenic').[14] A multiregression analysis using the National Veterans Affairs databases demonstrated that patients with cerebrovascular disease, cerebrovascular dementia, brain tumors, head injury and other brain disorders were more likely to develop new-onset epilepsy. In this study, a statin prescription was associated with a lower likelihood of developing epilepsy. However, this warrants further study before recommendating statins in epilepsy.[15]

Cerebrovascular Disease

Stroke is the leading cause of new-onset epilepsy beyond aged 65 years of age, accounting for 50–75% of epilepsy cases where a cause can be identified.[13] Post-stroke epilepsy usually develops within 3–12 months; the seizure risk increases 20-fold in the first year after a stroke,[16] but may still occur many years later.[17,18] Epilepsy and seizures are more likely after hemorrhagic than ischemic strokes: 80% compared with 5% developing seizures within 2 weeks, respectively.[19] A pragmatic approach for elderly patients developing new-onset seizures should include a thorough assessment for cerebrovascular risk factors.

Neurodegenerative Disorders

Neurodegenerative disorders, such as Alzheimer's disease, increase the risk of developing epilepsy by tenfold.[20,21] Alzheimer's disease, other dementias and other neurodegenerative disorders may account for 10–20% of all epilepsy in older people.[22] However, Scarmeas et al. recently demonstrated that unprovoked seizures, already more prevalent in the background population, are perhaps not as markedly increased in Alzheimer's disease as previously believed;[23] it was those with Alzheimer's disease onset at a younger age who appeared at highest risk. Multiple seizure types can occur in Alzheimer's disease, including myoclonus late in the disease.

Trauma

Age over 65 years is an important risk factor for post-traumatic epilepsy. Head injury, mostly from falls, causes up to 20% of epilepsy in the elderly.[24] The main factors suggesting higher risk of post-traumatic epilepsy are: loss of consciousness, post-traumatic amnesia beyond 24 h, skull fracture, brain contusion and subdural hematoma.[25] Head injury becomes potentially more serious with older age (with an increased risk of subdural hemorrhage, especially with anticoagulants or platelet inhibitors); such patients may benefit more from neuroimaging than younger patients.

Tumors

Seizures may be the presenting feature of tumors at any age, typically lower grade primary tumors, rather than higher grade or metastatic tumors. In later life, the most common tumors causing seizures are gliomas, meningiomas and metastases.[26,27] Seizures may be the first presentation of metastatic disease: in Lyman et al.'s study, 43% of those presenting with seizures from metastases had no previous systemic diagnosis of cancer.[28]

Psychiatric Illness

Psychiatric comorbidity is common and well-recognized in patients with epilepsy. Increasingly, conditions such as depression and anxiety may precede a diagnosis of epilepsy, thus raising the question: do psychiatric conditions predispose to epilepsy or do they represent independent risk factors for the condition? This was examined in 2009 by Ettinger et al., who, by comparing the frequency of psychiatric conditions in veterans with new-onset epilepsy with a control veteran population, demonstrated that conditions such as depression, anxiety, psychosis and substance abuse were more common in individuals with new-onset epilepsy.[29] However, after controlling for other risk factors for epilepsy, such as stroke, head injury, brain tumor and dementia, only psychosis was statistically significantly associated with epilepsy.[29] Although initially suggesting a relationship between psychiatric conditions and epilepsy in older patients, studies such as this do not necessarily demonstrate causality: based on database entries, this type of study may lack diagnostic accuracy. Furthermore, this veteran population was not truly representative of community elderly epilepsy populations. Clearly, we need further prospective work on the relationship between psychiatric conditions and epilepsy in older patients.

Other Causes

Acute symptomatic (provoked) seizures are common in the elderly, and often have a reversible cause. By definition, these are not epilepsy. Common causes include acute alcohol withdrawal, metabolic and electrolyte disturbances, such as hyponatremia, hypocalcemia and hypomagnesemia, and infections, either systemic or CNS.[30] Certain drugs commonly prescribed to elderly people, such as tramadol, also reduce seizure threshold, and are best avoided. Older people seem to be more susceptible to the epileptogenic effects of some other drugs, such as antipsychotics, antidepressants (particularly tricyclics), antibiotics, theophylline, levodopa, thiazide diuretics and even the herbal remedy, ginkgo biloba.[31]

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