The diagnosis of epilepsy is the same in elderly as in younger patients. It is a clinical diagnosis based on eyewitness description of the episodes. One of the major problems in diagnosing epilepsy in the elderly is that they may be unable to give a description of what is actually happening to them before or after an attack and, as they often live on their own, an episode may not have been witnessed. A classical tonic–clonic seizure is relatively easy to diagnose from eyewitness descriptions. Minor attacks such as absence or complex partial seizures are much more difficult to diagnose. Often they may consist of staring episodes where the person is not responsive for a few seconds. These can be followed by automatisms or confusion, often short-lived. An EEG is useful for the classification of seizure type. Only rarely can it be used to make a diagnosis, that is, if a seizure occurs while an EEG is being performed or specific diagnostic EEG changes occur. In addition, the post-ictal period can be longer in the elderly, lasting from hours to days, leading to the incorrect diagnosis of dementia.10 In more than 50% of elderly patients who were finally diagnosed with epilepsy, epilepsy was not the initial suspected diagnosis.11 In the elderly, after the first seizure the risk of recurrent seizures is very high, greater than 90%.3 Suggestions have been made that elderly patients should be treated with AEDs after the first seizure.

Transient Ischaemic Attacks (TIAs)

A TIA is a vascular event lasting less than 24 h. It tends to be associated with negative phenomena such as weakness or sensory loss. Conversely, epilepsy tends to have positive phenomena such as paraesthesias or jerking of a limb. However, at times it is difficult to differentiate simple partial seizures from TIAs. If consciousness is lost, it is very unlikely to be a TIA. It also has to be remembered that cerebrovascular disease is an important aetiological factor in the development of epilepsy.

Transient Global Amnesia

This is not an uncommon disorder occurring in later life, when a person has no memory for a significant period of between a few hours and a day or so. Eyewitnesses say that the person appeared normal and was able to perform complex tasks. On closer questioning, the person often was repeating the same questions such as ‘what time is it?’ A person tends to have only a single episode, so if repeated the diagnosis needs to be reconsidered. The symptoms are due to a defect in memory for events of the present and recent past. During the episode, consciousness is retained and there is no impairment in intellectual functioning. Studies have suggested that there is no increase in risk factors for vascular disease and no subsequent increase in cerebrovascular disease. There is, however, an increased incidence of migraine. Transient global amnesia is an important diagnosis to make in that, unlike epilepsy, people in the UK with this condition, after reporting to the Driving Vehicle Licensing Authority (DVLA), are allowed to continue driving.

Cardiac Arrhythmias

These are very important in the differential diagnosis of epilepsy in the elderly. If the brain is starved of oxygen, for whatever reason, a tonic–clonic seizure will result. Both tachy- and bradyarrhythmias can result in tonic–clonic seizures. Clues to the fact that the seizure may be a secondary phenomenon may be found in the prodrome. A history of feeling faint or palpitations should make a clinician suspect a cardiac cause for the episodes of loss of consciousness. A 24 h EEG with an ECG lead, videotelemetry and reveal devices can be useful in trying to differentiate between a cardiac and an epileptic episode. If the episode is cardiac in nature, the arrhythmia will begin before the abnormal electrical activity in the brain by a significant time lapse. It has to be remembered that during a seizure it is not uncommon for a cardiac arrhythmia to occur, but it will begin at about the same time as the abnormal electrical activity in the brain.

Syncope

If a person is kept upright during a vasovagal attack, it is not uncommon for a few myoclonic jerks to occur and in susceptible people a tonic–clonic seizure can result. The events leading up to the episode of loss of consciousness and also eyewitness descriptions are very important. The feeling of faintness, dizziness and the need to get fresh air preceding the episode make it likely that the episode was syncopal rather than epileptic in nature. The person is usually upright during the episode. They feel dizzy, queasy and giddy and often things recede or go black. Pallor is noted and often a cold perspiration. Nausea and vomiting occasionally accompany these symptoms. After falling to the ground, consciousness is regained very fast, and if the person lies down the episode can often be aborted. A few myoclonic jerks can occur, as can incontinence if the bladder is full. Micturition syncope, especially in men having to get up during the night, is a relatively common cause of loss of consciousness; so too is cough syncope. The elderly are more prone to syncope as they may have impaired cardiovascular reflexes or be on vasodilating drugs such as glyceryl trinitrate (GTN) or have carotid sinus hypersensitivity.

Psychogenic Epileptic Attacks

Psychogenic epileptic attacks are thought to be rare beginning in the elderly but are commonly misdiagnosed as people often have underlying organic problems.

Panic Attacks

It is rare for these to present de novo in the elderly as usually there is a life-long history. The person feels that something is going to happen. He/she feels the need to take deep breaths, becomes dizzy and light-headed, develops paraesthesias in the limbs and around the mouth and the legs become heavy. Symptoms can be reproduced by getting the person to hyperventilate. The initial precipitant was often a faint and panic attacks develop subsequently because of a fear of a further episode.

Drop Attacks

These are episodes of unknown aetiology where a middle-aged or older person, usually a woman, will suddenly drop to the ground. There is no preceding warning and consciousness is not lost. There is often bruising to face, hands and knees. After the episode, the person can get up immediately. The EEG is normal, even during a fall. There is no treatment.

Hypoglycaemia

Hypoglycaemia is a rare cause of tonic–clonic seizures. It obviously needs excluding in diabetic patients on treatment. Rarely an insulinoma can produce tonic–clonic seizures. Other metabolic causes such as hypocalcaemia can precipitate seizures.

Alcohol and Drugs

Alcohol abuse and withdrawal can precipitate seizures and it is important to take an alcohol history, even in the elderly. Many drugs, particularly tricyclic antidepressants, antimalarials, phenothiazines and butyrophenones, lower the seizure threshold and can precipitate seizures. The withdrawal of benzodiazepines occasionally can produce seizures.

Sleep Disorders

Seizures during sleep need to be differentiated from parasomnias, but usually epilepsy can be diagnosed by taking a good history from the patient and obtaining an eye-witness description of the episode. A REM (rapid eye movement) sleep behaviour disorder occurs when somebody acts out their dreams. Periodic limb movement disorders are characterized by periodic movements occurring during non-REM sleep. Most commonly people dorsiflex their ankles and flex their knees and hips every 20–40 s and this can be associated, in about 30% of patients, with restless legs syndrome. Hypnic jerks are a normal phenomenon occurring in about 70% of the population and consist of brief myoclonic jerks at sleep onset.