What is Functional Neurological Disorder (FND)?

From the Guidelines

Functional Neurological Disorder (FND) is a medical condition where patients experience neurological symptoms that cannot be explained by traditional neurological diseases or structural abnormalities, and is characterized by a complex interaction between physical and psychological factors, often triggered by physical injury, emotional trauma, or stress, though many patients have no identifiable trigger. It involves real neurological symptoms such as weakness, abnormal movements, sensory issues, seizures, or cognitive problems that are caused by a problem with the functioning of the nervous system rather than structural damage or disease 1. FND occurs when the brain's normal mechanisms for controlling the body malfunction, creating a disconnect between the brain and body. The condition is believed to result from a complex interaction between physical and psychological factors, and is not "all in the head" or imagined—the symptoms are real and can be severely disabling.

Key Characteristics of FND

• Involves real neurological symptoms that cannot be explained by traditional neurological diseases or structural abnormalities
• Characterized by a complex interaction between physical and psychological factors
• Often triggered by physical injury, emotional trauma, or stress, though many patients have no identifiable trigger
• Symptoms can include weakness, abnormal movements, sensory issues, seizures, or cognitive problems

Diagnosis and Treatment of FND

• Diagnosis is typically made by a neurologist using 'positive clinical signs' and is not a diagnosis of exclusion 1
• Treatment typically involves a multidisciplinary approach including physical therapy, psychological therapy (particularly cognitive behavioral therapy), and sometimes medication to address specific symptoms
• Early diagnosis and treatment are important, as outcomes tend to be better when intervention begins promptly
• Occupational therapy is also recognized as an integral part of multidisciplinary rehabilitation for people with FND, and may involve education, rehabilitation within functional activity, and the use of taught self-management strategies 1

Importance of Early Diagnosis and Treatment

• FND is relatively common, accounting for up to 30% of neurology outpatient visits
• Yet it remains widely misunderstood by both the public and some healthcare providers
• Early diagnosis and treatment are crucial to improve outcomes and reduce disability
• A multidisciplinary approach to treatment, including physical therapy, psychological therapy, and occupational therapy, can help to address the complex needs of patients with FND 1

From the Research

Definition and Characteristics of FND

• Functional Neurological Disorder (FND) is a condition characterized by neurological symptoms that lack an identifiable organic cause 2.
• These symptoms can consist of motor, sensory, or cognitive disturbances, and are not deliberately produced, often varying in severity 2.
• FND is also known as conversion disorder, and its diagnosis is based on clinical evaluation and the exclusion of other medical or psychiatric conditions 2, 3, 4.

Diagnosis and Diagnostic Challenges

• The diagnosis of FND should rest on clear positive evidence, typically from a combination of physical signs on examination or the nature of seizures 4.
• Recent advances in neuroimaging have shed new light on this disorder, and have the potential to predict treatment response 2.
• The diagnosis of FND can be challenging due to its phenotypic heterogeneity, and the need to differentiate it from feigning or malingering 2, 3.

Treatment and Management

• The treatment of FND typically involves a multidisciplinary approach, addressing each of the neurological symptoms and underlying psychological factors via a mixture of medical management, psychotherapy, and supportive interventions 2, 5.
• Rehabilitative interventions, such as physical and occupational therapy, are treatments of choice for functional motor symptoms, while psychotherapy is an emerging evidence-based treatment across FND subtypes 3.
• Clear communication of the diagnosis and the involvement of the multidisciplinary team is beneficial in the treatment of FND 4.

Subtypes and Mechanisms

• FND can be divided into subtypes, including motor (weakness and/or movement disorders) and seizure type symptoms 3.
• Four entities - functional seizures, functional movement disorders, persistent perceptual postural dizziness, and functional cognitive disorder - show similarities in aetiology and pathophysiology, and are variants of a disorder at the interface between neurology and psychiatry 6.
• The pathophysiology of FND includes overactivity of the limbic system, the development of an internal symptom model, and dysfunction of brain networks that gives movement the sense of voluntariness 6.