IN many ways the most fascinating patients seen by the Scottish Epilepsy Centre (SEC) are those who don't actually have epilepsy.

The centre, run by the charity Quarriers, is one of a kind. At its base in Bridge of Weir the charity first started an epilepsy "colony" more than 100 years ago.

In its current guise, the SEC offers expert assessment of people whose condition is complex and hard to control, with residential patients coming for longer periods than is often available under the NHS, typically staying at the centre for up to 30 days, where their condition can be monitored using electroencephalograms (EEGs) and video cameras, sometimes day and night.

This amounts to something of a gold standard of epilepsy diagnosis – longer-term monitoring of what happens to patients during seizures can be helpful, particularly as they commonly have limited memory of what has happened themselves.

With close observation of the seizures caused by their illness, medical staff can decide how best to treat it.

But the most remarkable thing about the centre is that only about 50% of the patients referred there have epilepsy alone. In around 15% of cases, the epileptic attacks are accompanied by other seizures, which EEGs show not to be neurological at all.

The remaining 35% have no true epileptic seizures, and hence don't have epilepsy.

Epilepsy is a neurological disorder characterised by attacks which are accompanied by abnormal electrical activity in the brain. As James Anderson, epilepsy neuropsychologist at the centre explains, if such activity doesn't show on the scan, it isn't epilepsy.

"A large part of our work is to look at the diagnosis and determine the best treatment. We also assess what events, if any, may look like epilepsy, but don't have the electrical physiological change of epilepsy."

Even if attacks are not epileptic in nature, patients still have a condition which can cause great dysfunction in their lives, he adds. " If you have a non-epileptic attack you can't drive, just the same as if you had epilepsy. It can be just as disruptive."

As a result the reaction from patients to such a diagnosis can range from relief to anger or confusion, he says. "There is a range of responses, as you can imagine.

"Some people have been under the assumption that they have had epilepsy for a great number of years, and discovering they haven't is something of a shock.

"You could have a huge amount of relief that you don't have a serious neurological disorder. We can then start identifying and removing medicines that people don't need."

That can be beneficial in itself as some anti-seizure medications are powerful and have significant side effects.

But Mr Anderson sees a range of other reactions. Some people are angry or feel they have been misled about their diagnosis, others are dismayed at the suggestion that their illness is more psychological than medical.

"There can be a degree of anger, and the thought of what to do about the treatment of your non-epileptic attacks can be daunting. For some people this definitive diagnosis has been a long time coming."

Epilepsy is often caused by a trauma to the brain of some description, sometimes before or during birth, or in later life. It can be linked to degenerative disease in old age.

It is more common in patients with learning disabilities and can be combined with a range of other conditions, which unfortunately means it can be harder to control for those patients.

But what causes non-epileptic seizures? There are a range of possibilities, Mr Anderson explains, not necessarily easily treatable. "A 'behavioural event' is a good way of describing it. It can be like a panic attack, but is beyond an individual's control.

"This is no way a conscious or a manipulative act on the patient's part, but it is often not treatable by medicine. While it may not be a medical problem, these attacks are not dismissed by the medical profession, they are real," he explains.

It is understandable, he adds, that misdiagnosis occurs. Epilepsy is complex and "difficult to get a handle on". A large number of other conditions can mimic its attacks.

But treatment can be about tackling other issues in the patient's present or past life.

"A tendency to have non-epileptic attacks can be triggered by sexual assault or other trauma including major or life-threatening illness. They can also be a symptom of people with extreme learning disabilities."

The Scottish Epilepsy Centre is currently housed in buildings completed in 1970 and will next year be replaced by a £6.4 million state-of-the-art 12-bed unit currently being built by Quarriers in Govan.

By its nature it deals with the more complex cases of epilepsy, and those which are causing difficulty in diagnosis or treatment.

Mr Anderson says the proportions of the centre's patients who attend mistakenly believing they have epilepsy are probably not mirrored in the general population.

"The advantage of this centre is the time we can spend with people and get a better understanding of what is going on."