Table 1

A range of potential mechanisms and aetiological factors in patients with functional motor disorders

Factors acting at all stages▸ ‘Organic’ disease
▸ History of previous functional symptoms
▸ Emotional disorder
▸ Personality disorder
▸ Socio-economic/deprivation
▸ Life events and difficulties
Predisposing vulnerabilities▸ Genetic factors affecting personality
▸ Biological vulnerabilities in the nervous system
▸ Perception of childhood experience as adverse
▸ Personality traits
▸ Poor attachment/coping style
▸ Childhood neglect/abuse
▸ Poor family functioning
▸ Symptom modelling of others
Precipitating mechanisms▸ Abnormal physiological event or state (eg, drug side effect hyperventilation, sleep deprivation, sleep paralysis)
▸ Physical injury/pain
▸ Perception of life event as negative, unexpected
▸ Acute dissociative episode/panic attack.
Perpetuating factors▸ Plasticity in CNS motor and sensory (including pain) pathways leading to habitual abnormal movement
▸ Deconditioning
▸ Neuroendocrine and immunological abnormalities similar to those seen in depression and anxiety
▸ Illness beliefs (patient and family)
▸ Perception of symptoms as being irreversible
▸ Not feeling believed
▸ Perception that movement causes damage
▸ Avoidance of symptom provocation
▸ Fear of falling
▸ Social benefits of being ill
▸ Availability of legal compensation
▸ Ongoing medical investigations and uncertainty
▸ Excessive reliance on sources of information or group affiliations which reinforce beliefs that symptoms are irreversible and purely physical in nature
  • Adapted from Stone and Carson.13

  • CNS, central nervous system.