Neurological deficit

Functional neurological disorder (FND) is a condition in which patients experience neurological symptoms such as weakness, movement disorders, sensory symptoms and blackouts. The brain of a patient with functional neurological symptom disorder is structurally normal, but functions incorrectly. According to consensus from the literature and from physicians and psychologists practicing in the field, "functional symptoms, also called "medically unexplained," "psychogenic," or "hysterical," are symptoms that are clinically recognisable as not being caused by a definable organic disease". Other terms for functional neurological disorder include functional neurological symptom disorder, conversion disorder, and psychogenic movement disorder/non-epileptic seizures. Functional neurological disorders are common in neurological services, accounting for up to one third of outpatient neurology clinic attendances, and associated with as much physical disability and distress as other neurological disorders. The diagnosis is made based on positive signs and symptoms in the history and examination during consultation of a neurologist (see below). Physiotherapy is particularly helpful for patients with motor symptoms (weakness, gait disorders, movement disorders) and tailored cognitive behavioural therapy has the best evidence in patients with dissociative (non-epileptic) attacks.

There are a great number of symptoms experienced by those with functional neurological disorder. It is important to note that the symptoms experienced by those with FND feel subjectively very real to the patient, and may be associated with debility. At the same time, the origin of symptoms is complex since it can be associated with psychiatric disturbance and secondary gain including litigation, disability status, family conflicts and other factors. The core symptoms are those of motor or sensory function or episodes of altered awareness

Functional neurological disorders are a common problem, and are the second most common reason for a neurological outpatient visit after headache/migraine. Dissociative (non-epileptic) seizures account for about 1 in 7 referrals to neurologists after an initial seizure, and functional weakness has a similar prevalence to multiple sclerosis.

Epidemiological studies and meta-analysis have shown higher rates of depression and anxiety in patients with FND compared to the general population, but rates are similar to patients with other neurological disorders such as epilepsy or Parkinson's disease.

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