Blood tests are seldom informative in patients with epilepsy but may be useful in the early days of life, when chemical abnormalities may precipitate seizures. A lumbar puncture may be carried out if an infection such as meningitis or encephalitis is suspected as causing epileptic seizures. Occasionally, removal of tissues (biopsy) for microscopic analysis may be helpful in rare causes of epilepsy; the tissues which are biopsied include skin or rectum (as these contain accessible nerve cells) or muscle. The diseases which are being tested for usually have manifestations other than seizures alone.
It is rarely necessary to repeat the EEG or a brain scan in most people with epilepsy. However, there are some exceptions to this general rule. Further EEGs may be helpful if treatment is not as effective as expected, or if, after a period of good seizure control, a patient’s seizures become more frequent. Some doctors recommend that an EEG should be repeated before a patient comes off treatment with anticonvulsants, but there is not much evidence that this helps reach a decision. There is rarely any justification for repeating a brain scan. However, if something suspicious is seen on a CT scan, then an MRI scan could be useful in confirming an abnormality, particularly if surgery for the epilepsy is being considered. Clearly if the epilepsy gets markedly worse, or the patient develops new symptoms such as weakness of a limb or develops new neurological signs, then it is essential to investigate the patient again.
In summary, laboratory investigation of seizures has a limited value. An ordinary EEG may rarely improve the certainty of diagnosis, though it more frequently helps ascertain the type of seizure and so the correct choice of anti-epileptic drug. The much more expensive tape-recorded EEGs and video monitoring of seizures do undoubtedly help discriminate between different types of seizures, and between real and simulated attacks.
CT or MR scanning may give a direct visual demonstration of the structural abnormality causing seizures, though this does not often influence management. Simple blood tests and skull X-rays, though cheap to perform, seldom show a relevant abnormality. With this knowledge, the neurologist will often embark upon few if any investigations. His perspective may be that he is faced with a problem that is common in his practice, and that there are well recognized and effective policies for coping with the matter. A good and kind neurologist will recognize that this professional perspective, based on his knowledge and experience, is not that of his patient, who is frightened and bewildered by the onset of events which he does not understand, but which he feels may have important effects on his life and career.
The technical aspects of the neurological consultation—the history, the differential diagnosis, the examination, any necessary investigation, and prescription of anti-epileptic drug—take
comparatively little time. Most of the consultation should be spent, in our view, in exploring the person’s attitudes and knowledge about epilepsy, and the effect that epilepsy may have on his life, so that practical advice and support can be given. Often this may take more than one consultation. How much of this support should be provided by the neurologist and how much by the family doctor depends upon the personalities of the doctors and the patient, as well as upon the available time. What is disastrous for the patient is if each doctor assumes that the other is coping with these aspects.
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