Three studies published in the 13 June issue of the journal Neurology have highlighted the difficult area of distinguishing psychogenic non-epileptic seizures from epilepsy, and point to new clues that could help diagnosis.

Psychogenic non-epileptic seizures can look like epileptic seizures but actually have a psychological cause. They are so difficult to distinguish from epilepsy that it's estimated that between 20 and 30% of people with a diagnosis of epilepsy in fact have psychogenic seizures. People with psychogenic seizures do not respond to anti-epileptic medication. Many of them are however prescribed high doses of this medication, resulting in considerable side effects, because it's thought they have a difficult-to-treat form of epilepsy. It's estimated it takes an average of eight years for them to get a correct diagnosis.

Eyes closed or open?
The first study looked at eye opening or closing during a seizure and whether this could be used to differentiate between epileptic and non-epileptic episodes. Dr Steve Chung and his research team from Phoenix, Arizona, USA, looked at video-EEG evidence from 52 patients with psychogenic non-epileptic seizures, and 156 patients with epilepsy.

They found that 96% of patients with non-epileptic seizures kept their eyes closed throughout their seizures; 97% of patients with epilepsy kept their eyes open (except for blinking) during their seizures. If this finding is confirmed, this could be a very reliable and simple indicator, as many patients' family members who witness seizures easily notice this factor.

Emergency treatment
The second study from Berlin in Germany looked at the treatment of status epilepticus in intensive care. Status epilepticus is a continuous seizure, or a series of seizures, lasting more than 30 minutes, and it is a medical emergency. Both epilepsy and non-epileptic seizure disorder can cause this state, and of course require very different treatments, with drugs that can themselves be harmful. Here 18 patients with continuous generalised convulsive seizures that did not respond to emergency drugs were studied. Dr Martin Holtkamp and colleagues found that the patients with non-epileptic seizures were:

• more likely to be younger (less than 30 years)
• more likely to have a port system fitted (to ease administration of intravenous drugs)
• more likely to receive high doses of emergency drugs
• more likely to have lower blood levels of a key enzyme that is associated with epileptic seizures.

These critical indicators could help emergency doctors to a correct diagnosis when prompt treatment is vital.

Causes of psychogenic seizures
In the third study, researchers at the West of Scotland Epilepsy Service in Glasgow looked at social, medical and other characteristics of patients who have non-epileptic seizures, and how these vary depending on the patient's age when they are diagnosed.

Dr Roderick Duncan and his team found that cases diagnosed after the age of 55 years were more likely to be men, and more likely to be associated with serious physical health problems (such as heart disease, stroke, high cholesterol or high blood pressure) which had been difficult and frightening to deal with. Younger cases were in contrast more likely to report sexual abuse. This suggests that the underlying psychological causes of non-epileptic seizures changes with age. The development of chronic ill health, especially when it has been frightening to the patient, may be an important triggering factor in older patients.

Conclusion
These three studies highlight the difficulties facing doctors in telling the difference between epileptic and non-epileptic seizures, and also the importance of a correct diagnosis. Doctors and patients need to be more aware of the existence of psychogenic non-epileptic seizures, to speed up correct diagnosis and treatment.

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