10 Functional neurological symptoms

Functional Neurological Disorder (FND) is at the complex interface of the body and mind and therefore also physical and mental health. It has been neglected by medicine so little is known about its mechanism or treatment. However, there have been recent critical developments, particularly establishing it is as common as Parkinson’s or multiple sclerosis and associated with poor outcomes and consequently associated with very high rates of disability and both health and social care costs. There have also been critical changes in its diagnosis. The historical requirement of identifying causative stressors has been removed as it is now clear that these are not found in a significant proportion of patients. Instead, there has been increased emphasis on identifying ‘positive neurological signs’ which allow its reliable distinction from other disorders. Such signs can also be explained to patients to help them to understand the basis of the diagnosis and how it can be caused by dysfunction of cognitive processes such as attention and illness representations, thereby increasing acceptance of a complex and stigmatised diagnosis. The widespread adoption of the acronym FND and therefore the term ‘functional’, an aetiologically neutral term, has also facilitated critical steps in uniting patients and clinicians. FND patients regularly have current and/or past comorbid symptoms presenting to other specialities such as fibromyalgia and Irritable Bowel Syndrome, which can be viewed as related disorders with overlapping mechanisms. Insights from FND research are therefore well positioned to inform the broader field of functional disorders which account for approximately 30% of morbidity and costs across medicine.