Epilepsy is one of the most common neurological conditions, particularly in young people, with over 70 per cent of those who develop epilepsy doing so before the age of 20. Unlike most other neurological diseases it is treatable, with most patients going on to lead a normal, fit-free life. It is very important, therefore, that the initial diagnosis and treatment are correct.
Diagnosing epilepsy
As usual, the key to diagnosis is in the history. You should ask the patient or a witness whether the patient was acting oddly before the episode; about any wetting or tongue biting; the length of the episode; about any loss of consciousness; generalised or specific movements; or palpitations. Also check for history of excess alcohol; drug history, especially non-prescription drugs; fever (in a young child) and family history of epilepsy.
Investigation
In young people referral to a neurologist is essential. Many centres now run 'first fit' clinics, allowing speedy and standardised assessment.
In older patients a cause is more likely to be found. Alcohol or drug withdrawal, cerebral metastases from occult tumours and cardiac arrhythmias should be considered. An ECG and, if indicated, continuous ECG monitoring, is essential. Pseudo-seizures are also common, often with a background of psychological or social distress.
EEG is the gold-standard investigation for diagnosis and classification, however, only about a third of people with epilepsy will have a positive result on first testing, rising to about 70 per cent with repeat recording.
EEG with synchronised video during a fit is almost certain to be diagnostic. Sleep EEG can also be helpful.
Brain imaging in the form of MRI scanning will show abnormalities in about a third of those presenting with epilepsy, such as AV malformations - most are not treatable, however.
CT scanning is less sensitive but useful if MRI scanning is contraindicated.
Treatment
The decision to start treatment is dependent upon the risk of further seizures. Generally, patients with tonic-clonic seizures, those with EEG abnormalities, those with congenital neurological deficits and those particularly keen to avoid further seizures are offered treatment early.
Drugs are generally used as monotherapy, starting with a low dose and increasing until fits are controlled or there are unacceptable side-effects. If one particular drug is unsuitable, it is tapered off while a new drug is being added.
Drugs suitable for partial seizures include carbamazepine, sodium valproate, lamotrigine and oxcarbazepine.
Drugs suitable for generalised seizures or seizures difficult to classify are sodium valproate and lamotrigine.
When monotherapy fails, it may be necessary to use two or even three appropriate agents.
After a fit-free period, patients may be keen to stop therapy. Complex tables exist indicating the likely risk of recurrence. If control is good, however, and if the patient has resumed driving, the risk may not be acceptable.
Surgery can sometimes help in drug-resistant patients, usually in the form of resection of parts of the brain. This tends to be reserved for severe and intractable disease.
Status epilepticus
This is defined as epilepsy continuing for more than 30 minutes. Treatment in the community involves general measures such as administration of oxygen, obtaining IV access and administration of diazepam or lorazepam.
Fortunately, rectal diazepam usually works well, particularly in children, because obtaining IV access can be problematic.
Young women and epilepsy
Problems can arise with enzyme-inducing drugs when prescribing the oral contraceptive pill.
In pregnancy, anti-epileptic drugs increase the baseline risk of fetal abnormality by two or three times, but uncontrolled seizures are possibly more dangerous. Generally, the simplest regimen at the lowest dosage possible is the best plan, and it may occasionally be possible to withdraw drugs completely.
Pre-conceptual counselling is advised, but is unfortunately not always possible.
Driving
DVLA regulations state that a person may not drive for one year after a fit. This can obviously have major implications for employment and family life. Regulations for nocturnal epilepsy are more complex (see www.dvla.gov.uk).
Dr Glenesk is a GP trainer in Aberdeen
Key points
- Epilepsy is one of the most common neurological conditions.
- The key to diagnosis is in asking the right questions and it is important to refer to a neurologist.
- Treatment consists of anti-epileptic drugs and/or surgery in severe cases. If monotherapy fails, two or three drugs may be necessary.
