What is a functional neurological disorder?

Sometimes patients present with neurological symptoms that cannot be explained by “structural” causes. By structural causes I mean there is no identifiable cause of the symptoms, even using multiple tests. The sequence of events is as follows: you go to your GP with neurological symptoms- this could be a weakness down one side or visual symptoms, for example, blurring of vision or seeing double- and then you are referred to see a neurologist. Your neurologist assesses you and arranges for scans to be done or other tests. Assuming the tests all come back as normal, you go back to see your neurologist who tells you that the news is good, all the tests are normal and they cannot find anything wrong with you! This should be good news, right! And yes, it is good that your test results are normal but you still have your symptoms. So what do you do next? Probably seek a second opinion. Then you go through the exact same process and maybe a few more tests and the outcome is the same. Again you are told that there has been no cause found for your symptoms. Yet you still have symptoms so what can you do next? You are most likely suffering from a functional disorder of your nervous system- as in there is a breakdown of the function of your nervous system and not the structure. When I say structure I mean a problem that can be seen in the nervous system structure such as a stroke or multiple sclerosis as examples that leave marks on the brain. In the case of a functional disorder the brain structure looks normal. Unfortunately, rather than say “I don’t know what is wrong with you” doctors often prefer to say “there is nothing wrong with you”. Most doctors and even a lot of neurologists are unfamiliar with functional neurological disorders. This leads to people getting the impression that their symptoms are not real or they are “all in your head”. This is, firstly, not true and secondly, in no way helpful in terms of formulating a plan to manage and hopefully resolve your symptoms.

 

A functional disorder of the neurological system is where the problem lies within the function and not structure of your nervous system. This does not in any way mean that the symptoms are made up or “in your head”. They are as real as any other symptom from any other cause. The good thing about a functional neurological disorder is that the chance for 100% recovery is high. These conditions have been given other names such as a psychogenic disorder, dissociative disorders or non-organic. I prefer the term functional as I believe it is the most accurate- there is a disorder of the functioning of your nervous system. Also, psychogenic implies there is a psychological or psychiatric cause and this is not always the case. You do not have to be stressed, depressed or anxious to develop functional neurological symptoms. However, if there is an underlying psychological stressor, identifying this is very important.

The underlying cause of a functional neurological illness can be difficult to identify. In years gone by it was assumed that there had to be an underlying stressor or psychiatric cause for the symptoms. For many years the presence of a psychological stressor formed part of the diagnostic criteria- in other words you had to have an identifiable psychological stressor in order to receive the diagnosis of a functional neurological disorder. This is no longer the case. Many patients with a functional neurological disorder will not report any adverse psychological event as a potential precipitant. There may have been a physical injury as a precipitant or there may not be any obvious precipitant. What is agreed upon amongst doctors who diagnose and treat this condition is that it is at the interface between neurology and psychiatry. People experience physical injuries frequently but functional neurological disorders resulting from a physical injury are uncommon. The difference between those who develop the functional illness and those who don’t is thought to be that the former may have an underlying predisposition to a greater psychological impact from the physical injury.