Functional neurological deficit

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The diagnosis of functional neurological deficit (functional neurological disorder) provides an umbrella term for a variety of symptoms which look like medical symptoms but which have no medical cause. They are thus felt to be of psychological (whether of conscious or unconscious origin). Presentation may be similar to a wide range of other neurological conditions from paralysis to chronic fatigue and seizures. An example will suffice e.g. when an individual is stressed they might get a twitch in their eye. This will in every usual way resemble a tic found in a neurological disorder but it is not this, it is simply a stress-response manifested in the nervous system. A similar stress-response could just as easily manifested as a raised heart-rate in the cardio-vascular system or a heartburn in the gastro-intestinal system. Children will often complain of a non-localised central abdominal pain when stressed. This is a real pain, as the eye-twitch, and raised heart-rate and heartburn are real symptoms, but the cause is not medical, it is psychological, a stress-response. These are real symptoms and they have a real cause, but it is just that the cause is stress, not medical illness. Functional neurological deficit can present with any motor or sensory symptom in the body including:

  • Weakness / paralysis of a limb or the entire body
  • Impaired hearing or vision
  • Loss / disturbance of sensation
  • Impairment or loss of speech
  • Fixed dystonia, unlike normal dystonia
  • Tremor, myoclonus, or other movement disorders
  • Gait problems


Involves identifying with the aid of the patient predisposing, precipitating and perpetuating factors. Then working with the patient to manage their stress levels and their stress-response. For some patients who have deeply entrenched beliefs that there is a medical cause it is unproductive to directly challenge this belief and a gradual course of physiotherapy can allow the patient to slowly 'put-down' or move away from their symptoms.