The main pitfall associated with seizure disorders and epilepsy is misdiagnosis. It should be realised that not all seizures are generalised tonic–clonic in type. The most common misdiagnosed seizure disorders are complex partial seizures (an underdiagnosed disorder) or the tonic or atonic seizures.
The diagnosis of epilepsy is made on the history rather than the EEG so a very detailed description of the events from eyewitnesses is important.
The features of complex partial seizure (described in CHAPTER 54) have many variations, the commonest being a slight disturbance of perception or consciousness. The complex partial seizure may evolve to a generalised tonic–clonic seizure. A simple partial seizure may also do this.
In tonic–clonic seizures the patient may become momentarily rigid or fall to the ground and perhaps have one or two jerks only.
Misdiagnosing behavioural disorders
It is important to differentiate between a fit and a behavioural disorder, but it can be difficult. About 20% of apparently intractable ‘seizures’ are considered to be non-epileptic (pseudoseizures, i.e. emotionally based).10 These often resemble tonic–clonic seizures but usually there are bizarre limb movements. Ancillary testing, especially with video EEG recording, can help overcome these diagnostic problems but the differentiation may be difficult as the most common situation for pseudoseizures is in the person who has real fits.
Polypharmacy may be counterproductive for the patient and the seizure disorder. This is especially applicable to drugs with a high incidence of side effects. If a patient is taking several medications, management of the case needs questioning and perhaps reconsidering with a consultant’s help.
Seizure control may be improved by reducing polypharmacy. When initiating treatment it is best to select one drug and increase its dose until its maximum recommended level, the onset of side effects or appropriate control. If control is not obtained, the drug should be replaced with an alternative agent but a crossover period is essential. Monotherapy is preferred but combination therapy is often acceptable.
The question should be asked at some stage ‘Does this patient really need medication?’ Some patients are kept on anti-epileptics for too long without any attempt being made to wean them off medication or to transfer them onto anti-epileptics less prone to side effects. Patients should not be left on inappropriate drugs especially if side effects and drug interactions are a problem.
Drug interactions with anti-epileptics should always be kept in mind. The most serious of all is the interaction with the oral contraceptive pill because pregnancy can occur. Erythromycin and carbamazepine interact.