Epilepsy is a neurological disorder characterised by recurrent seizures. It affects one in 200 people and is the most prevalent serious neurological disease.
In an average list size of 3,000, most GPs can expect to see two to three new cases of epilepsy per year, and care for about 15 patients with chronic epilepsy. Epilepsy has huge public health significance, costing the NHS £1 billion a year.
The primary manifestation of epilepsy is recurrent, unprovoked seizures. Continuing seizures are associated with significant personal burden, including psychiatric and cognitive morbidity, and an increased risk of death through accidental injury, status epilepticus and sudden unexpected death in epilepsy (SUDEP).
Epilepsy may arise through an acquired brain injury, such as infection (encephalitis), tumour, head injury or stroke. Identification of the cause of epilepsy is an important aspect of acute and chronic assessment of epilepsy seizures, as treatment may need to be urgently directed against the underlying cause.
Alternatively, epilepsy may arise as a developmental condition through no cause other than a genetic predisposition.
In addition to aetiology, epilepsy may also be classified according to the anatomical location of the seizure. If the seizure arises from a focal area of the cerebral cortex the seizure is termed 'focal' or 'partial'. The clinical features of the seizure depend on the precise area of brain involved. If the seizure is seen to arise from the whole cortex at onset then the seizure is termed 'generalised'.
EEG showing focal epileptic spikes over the left mid-temporal region (Photograph: SPL)
A critical aspect of the diagnosis is the eyewitness description. Patients referred to neurology outpatients should be asked to make every effort to bring an eyewitness to their seizure with them to the initial outpatient appointment.
Most patients will require brain MRI and EEG, although it should be noted that a normal EEG and brain scan does not exclude the condition. Where there is doubt about the diagnosis, both specialist cardiology and neurology assessments may be required.
Misdiagnosis of epilepsy is common, amounting to 20 per cent in some case series. Misdiagnosis is most common with syncope, since syncope may be associated with motor activity resembling both complex partial seizures (focal seizures associated with loss of or altered awareness) as well as generalised epilepsy convulsions.
Accurate distinction between syncope with motor phenomena and epilepsy may require considerable expertise.
Patients with a generalised tonic-clonic convulsion should be kept away from dangerous obstacles and placed in the recovery position. If appropriate, it may be necessary to administer oxygen, monitor the ECG, BP, oximetry or establish IV access. Check for hypoglycaemia.
Deciding whether an acute seizure presenting to primary care should be referred directly to A&E or for an outpatient neurology appointment requires considerable clinical judgment. In general, patients presenting with a seizure should be referred immediately to A&E in the event of:
- A prolonged first seizure (>five minutes).
- Serial seizures (>two in 24-48 hours).
- Mental state not returning to baseline (for example, any persisting altered mental state with or without evidence of intoxication).
- Age >40.
- Recent head injury.
- History of cancer, anticoagulation or immunosuppression.
- Persisting headache or fever.
- New neurological signs.
Referral to neurology outpatients rather than urgent referral to A&E might be considered if the seizure was brief, non-focal, uncomplicated, followed by recovery to full and normal consciousness, with a normal general and neurological examination, normal ECG, and where the patient has a safe home environment and timely neurological assessment is assured.
Treatment of seizures
Treatment may be aimed at the underlying condition or the epilepsy itself. The aim of treatment in epilepsy is to reduce the frequency of seizures and minimise the risk of seizure-related harm, including death.
Decisions regarding treatment are complex, and where possible should be made by an epilepsy-competent service.
Women of childbearing potential pose particular difficulty, in relation to the teratogenic risks associated with antiepilepsy drugs (AEDs) and the occurrence of drug interactions between some AEDs and hormonal contraception.
Factors influencing the decision to treat are highly individualised and depend on the cause of the seizure, the number of seizures that have occurred, the results of imaging and electrophysiological investigations and personal preferences.
In general, women of childbearing age should avoid valproate because of its high teratogenic risk and concerns regarding neurodevelopmental delay in children born to mothers taking valproate. However, valproate may be the only effective AED for some patients.
All AEDs have potential adverse effects that need to be discussed with the patient. All women of childbearing potential need to be warned of the teratogenic risks associated with AED therapy and advised of the importance of pre-conception counselling by a neurologist expert in epilepsy.
Patients who have been seizure free for two or more years on AED therapy, should be referred to a neurologist to determine if they might safely withdraw from their medication. There is increasing awareness that patients with epilepsy are at a heightened risk of SUDEP and this aspect of their condition requires sensitive discussion.
The prognosis of epilepsy varies greatly, even between patients with the same seizure type or epilepsy syndrome.
A diagnosis of epilepsy has important implications for the patient and their family. Driving is an issue most patients regard as important. The DVLA guidelines have been revised and are available to medical practitioners and patients. All patients following a suspected first seizure must be advised to inform the DVLA and not to drive until given permission to resume.
Patients should be advised to avoid situations where sudden loss of consciousness could be catastrophic, such as dangerous sports pursuits, bathing in a full tub and unaccompanied swimming.
- Dr Sharma is a consultant neurologist at Imperial College London and Hammersmith Hospitals, and Dr Johnson is consultant neurologist, Imperial College London and The Princess Margaret Hospital, Windsor, Berkshire.