when confronted with evidence that appears to contradict their story. When symptoms are purely subjective, for example pain, it is often difficult to confirm or refute a neurological diagnosis, for example of a complex regional pain syndrome, but evidence supporting the diagnosis of malingering can be obtained by documenting inconsistencies in resulting disability by video surveillance.
One common problem in neurological medicolegal practice is diagnosing Functional Neurological Disorder (FND), sometimes known as somatization, conversion disorder, hysteria or medically unexplained neurological symptoms. Like malingering, it is characterized by neurological symptoms in the absence of a physical cause, but unlike malingering there is no conscious elaboration of symptoms and the symptoms are entirely unconscious and emotionally-generated. It is common, and has been estimated that it comprises about one third of the workload of most neurologists, yet is poorly understood. Patients with FND tend to have a high use of clinical services and thick medical records.
Diagnosis is often suspected by a non-specialist but usually requires confirmation by a specialist. There may be dispute between experts on whether symptoms are physical or functional, especially if the claimant has suffered a head injury with no evidence of damage on neuroimaging. Non-neurological specialities also frequently see patients with functional symptoms, for example non-cardiac chest pain, breathlessness, irritable bowel syndrome, fibromyalgia and numerous types of pain syndromes. Most cases of chronic fatigue syndrome (CFS/ME) are likely emotionally-generated. It is therefore unsurprising that patients with functional neurological symptoms often have other functional non-neurological symptoms.