Epilepsy in Elderly People

Most new seizures in elderly patients are partial in onset with or without secondary generalisation. Idiopathic epilepsy is rarely detected later in life.

• Old age is now the most common time in life to develop epilepsy. Many affected elderly people will have neurodegenerative, cerebrovascular or neoplastic disease.
• Approximately 1.5% of the population over the age of 70 years is diagnosed with active epilepsy.¹

Risk Factors

• Underlying factors can be identified in a greater proportion of elderly patients than younger patients, including cerebrovascular disease, dementia and tumour.
• Cerebrovascular disease is the most common underlying factor.
• Dementias of non-vascular origin give rise to seizures that are often easy to control. Alzheimer's disease and epilepsy often coexist.
• The most common tumours found to produce seizures in later life are gliomas, meningiomas, and metastases. Seizures often have focal features but elderly patients do not always show neurological signs.¹
• Trauma is common in old age and older people are more likely to develop post-traumatic epilepsy. Subdural haematoma is a potentially treatable cause of epilepsy in elderly people.
• The peak incidence of first seizures related to alcohol withdrawal occurs in late adult life.
• Drug-induced seizures are most likely to be associated with use of more than one drug, high doses and coexisting illness.
• Infective and metabolic disturbances, cardiac disease, renal failure, hypothyroidism, hypoglycaemia, electrolyte disturbances, and hepatic impairment may be reversible causes of unexplained seizures. Seizures resulting from anoxic brain injury might occur with cardiac and respiratory disease.
• Other possible underlying causes are hypertensive encephalopathy and cerebral vasculitis.

• A reliable history and a witnessed event are generally of more value than investigations.
• There may be a history of trauma with evident bruises, cuts or burns.
• There may be a witness report of pallor, cyanosis, abnormal movements, tongue biting, urinary incontinence, and impaired conscious level, or postictal features, e.g. confusion, headache, drowsiness, and Todd's paresis.
• Nearly all de-novo seizures in elderly people are partial in onset with or without secondary generalization.

• The differential diagnosis of seizures in the elderly includes:²
  • Neurological: transient ischaemic attack, transient global amnesia, migraine, narcolepsy, restless legs syndrome
  • Cardiovascular: vasovagal syncope, orthostatic hypotension, cardiac arrhythmias, structural heart disease, carotid sinus syndrome
  • Endocrine/metabolic: hypoglycaemia, hyponatraemia, hypokalaemia
  • Sleep disorders: obstructive sleep apnoea, hypnic jerks, rapid eye movement sleep disorders
  • Psychological: non-epileptic psychogenic seizures.
• Common problems that need to be considered include cardiac arrhythmias, hypoglycaemia, hyperglycaemic non-ketotic states, postural hypotension, carotid sinus sensitivity, adverse drug effects and vasovagal episodes.
• Seizures may be the only manifestation of carotid occlusion in some patients. Limb tremor can arise with carotid basilar ischaemia, resembling simple partial motor-seizure activity.
• Complex partial seizures presenting as confusion may be misdiagnosed as psychiatric symptoms.
• Transient global amnesia: anterograde amnesia that resolves fully within 24 hours, with no neurological or cognitive sequelae.
• Sleep disorders: patients may only suffer night-time seizures.
• Hypothyroid neuropathy can be confused with partial seizure activity.
• Psychogenic non-epileptic attack disorder (NEAD) may present for the first time in later life, but this is unusual.

• Investigations will depend on the presentation but include ECG, ambulatory ECG, carotid and basilar artery ultrasound, orthostatic blood pressure measurement, and routine biochemical and haematological screening can help differentiate between possible underlying causes.
• Initial blood tests should include full blood count, ESR, fasting glucose, renal function, electrolytes and thyroid function tests.
• Neuroimaging to detect intracerebral lesions. MRI is usually the preferred investigation, being more accurate than CT, with the exception of subarachnoid haemorrhage.
• EEG: less specific and sensitive than neuroimaging in the investigation of epilepsy in elderly people.¹ EEG abnormalities in healthy elderly individuals are common. EEG can occasionally help to identify seizure type. The diagnosis of non-convulsive status epilepticus can be confirmed when continuous epileptiform activity is recorded in a confused patient.

• Education of patients, carers and relatives about cause, cautions and treatment of seizures.
• Treatment for provoked seizures should be directed towards the underlying cause.
• All elderly people reporting more than one well documented or witnessed unprovoked event should be offered antiepileptic drug treatment. Whether treatment should be started after a single unprovoked seizure remains controversial.²

Antiepileptic drugs

• Low-dose drug regimens can help keep to a minimum adverse effects and drug interactions. Most elderly patients require smaller doses than younger adults. Adverse effects can be kept to a minimum by starting with a low dose and titrating slowly.
• Elderly patients are more at risk of side-effects and idiosyncratic reactions.¹
• Long-term antiepileptic drug treatment is an independent risk factor for osteoporosis.
• Drugs with a high risk of neurotoxicity should be avoided.
• Few clinical trials of AEDs have been performed specifically in the elderly. Double-blind trials support the use of newer agents such as lamotrigine and gabapentin ahead of carbamazepine for the treatment of partial seizures and generalized tonic-clonic seizures, mainly because they produce fewer neurotoxic side effects.¹
• Valproate is a suitable alternative as it is well tolerated in the elderly and implicated in fewer interactions than is carbamazepine or phenytoin.
• Elderly people may be particularly susceptible to the sedative and behavioural effects of phenobarbital.

• The post-ictal phase is frequently extended in elderly patients and could contribute to physical injury sustained during seizure activity. Falls, burns, fractures, lacerations, strains, and severe bruising can lessen quality of life and affect socioeconomic status.
• Those affected often lose confidence and independence. Poor mobility and impaired self-confidence can result in admission to residential care.
• Mortality rates in older patients with epilepsy are high, particularly for those who present in status epilepticus. Rates of sudden unexpected death are also higher than average in the elderly.

• Most older patients will remain seizure-free on antiepileptic drug monotherapy. Inadequate seizure control should raise the suspicion of poor adherence or progressive neurodegenerative disease.
• Older people who present with a single seizure are more likely than younger individuals to have a further seizure.
• Complete seizure control can be expected in about 70% of elderly patients.