A Unified Mechanism for Functional Neurological Symptoms

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From the earliest medical records to the present day, doctors have separated out a group of patients from those with a typical "organic" cause for their physical symptoms. These patients have had many labels: "hysteria","conversion", "medically unexplained", "functional". Patients with functional symptoms are seen across primary care and all medical specialities, but are particularly common in neurological practice. Here they make up about 16% of those seen in neurology outpatient clinics, making functional neurological symptoms (FNS) one of the commonest diagnosis of neurology outpatients. People with these symptoms are, as a group, as disabled and experience as poor a quality of life as patients with Parkinson's disease or multiple sclerosis. Despite this, clinical services for such patients are poorly developed, research into causes of symptoms and treatment is very limited, and attitudes in society and within medicine to patients with functional symptoms are often poor.With this work, we want to test a new theory for how functional symptoms can arise from the brain. One of the difficulties in understanding functional symptoms is that the brain and the rest of the nervous system appears to be intact, despite severe symptoms. Indeed in patients with some types of symptoms, for example people with limb weakness, it is possible to demonstrate on examination that the apparently weak limb can generate normal power, even though the patient cannot get this to happen him or herself. We believe it is vitally important for research and development of better diagnosis and treatment for us to understand how functional symptoms are produced by the brain. We have previously developed a theory that we believe provides a reasonable mechanism for how symptoms are produced. We have already gathered evidence that supports this theory in patients who have functional symptoms affecting movement (e.g. weakness, tremor) and sensation (e.g. numbness). We now want to move forward and test if this theory can also account for symptoms experienced by people with chronic fatigue syndrome and non-epileptic attack disorder. Chronic fatigue syndrome is a disabling condition characterised by persistent fatigue in the absence of a clear medical cause. We believe that fatigue in chronic fatigue syndrome may occur because of abnormal activation of a network of structures in the brain that are usually involved in signalling the presence of infection and inflammation in the body and which give rise to a common set of symptoms experienced by everyone (and indeed across species) when infection or inflammation occur (known as the "sickness response"). This sickness response is usually short-lived, but we believe that the system could be abnormally activated in people with chronic fatigue syndrome in the absence of any ongoing infection or inflammation in the body. Non-epileptic attack disorder is a common cause of fit-like episodes which can be prolonged and very frequent. We know that these attacks are different from epilepsy, as there is no epileptic activity on brainwave (EEG) recordings performed during such attacks, but it is not known what is happening in the brain prior to and during attacks that could be responsible for the symptoms. We believe that changes in the brain's focus of attention in an abnormal way towards the body is an important part of triggering the attacks, and we will test this in our study.If our theory is correct, then when people get better with treatment then we should see corresponding changes in the way the brain is working. We will therefore test if particular aspects of brain function which our theory predicts are involved in generating functional symptoms become more normal when people with functional symptoms go through successful treatment. This would be a key step in proving or disproving our theory for how functional symptoms can be produced by the brain, and will help with future treatment development.