Table 1

 A scheme for thinking about the aetiology of functional symptoms in neurology

Predisposing• Genetic factors affecting personality• Poor “attachment” to parents and others• Childhood neglect/abuse
• Biological vulnerabilities in nervous system?• Personality/coping style• Poor family functioning
• Disease
Precipitating• Abnormal physiological event or state (e.g. hyperventilation, sleep deprivation, sleep paralysis)• Perception of life event as negative, unexpected• Symptom modelling (via media or personal contact)
• Physical injury/pain• Depression/anxiety• Life events and difficulties
• Acute dissociative episode/panic attack
Perpetuating• Plasticity in CNS motor and sensory (including pain) pathways• Perception of symptoms as being outwith personal control/due to disease• Fear/avoidance of work or family responsibilities
• Deconditioning (e.g. lack of physical fitness in chronic fatigue, deconditioning of vestibular responsiveness in patients with dizziness who hold their head still)• Anxiety/catastrophisation about cause of symptoms• The presence of a welfare system
• Neuroendocrine and immunological abnormalities similar to those seen in depression and anxiety• Not being believed• Social benefits of being ill
• Avoidance of symptom provocation (e.g. exercise in fatigue)• Availability of legal compensation
• Stigma of “mental illness” in society and from medical profession