Functional Movement Disorders

What are Functional Neurological Disorders (FND)?

Functional neurological disorders represent a group of disorders where there are often distressing and disabling neurological signs and symptoms that occur which cannot be accounted for by other known disease entities.  For example, shaking or tremor that is not typical of Parkinson's disease or essential tremor.  With functional neurological disorders, there is no structural damage or degeneration of the nervous system.  Instead there is a functional problem (or malfunction) of the brain which is often reversible. FND manifest with symptoms that are typically seen in neurology clinics, for example, seizures-like episodes, weakness, abnormal sensations, pain, walking problems and movement disorders.  Functional Movement disorders (FMD) represent a significant portion of functional neurological disorders.  FMD also have many types such as shaking (or tremor), abnormal muscle spasm and posturing (also referred to as dystonia) and jerky movements (also referred to as myoclonus) and there are others. These disorders are quite common. 

What are the signs and symptoms of FMD and how is it diagnosed?

Tremor or shaking is the most common type of functional movement disorders making up about half the cases, followed by painful spasms and abnormal postures and jerking movements, but the symptoms can manifest in a variety of abnormal movements, even looking like Parkinson's disease or including multiple types in one patient.  The symptoms of functional movement disorders generally come on suddenly and can become severe in a very short time. The symptoms can also fluctuate in type, location, frequency and severity. Functional disorders can occur in combination with other movement disorders, or independently.  Many patients also have primary psychiatric disorders such as anxiety and depression which may not have been previously recognized. The symptoms of functional movement disorders are specific and recognizable. The diagnosis is clinical, based or medical history and neurological examination.  All testing, including imaging, are normal.  The diagnosis of functional movement disorders is generally made by neurologists, not psychiatrists.  

What causes FMD?

The precise cause of FMD, as with many neurological diseases, remains unclear, particularly because FMD are not caused by structural brain damage, but a functional change. These disorders are often triggered by an illness, or a physical or emotional event.  In the past, these disorders were referred to as "psychogenic disorders" because in many patients the symptoms were triggered by psychological symptoms or stressors.  However, this is not always obvious, to the patient or the physician, nor is a psychological event or stressor even necessary to trigger FMD.  Nevertheless, the disorder is felt to be the result of a complex interaction between psychology and neurology, or, put differently, emotion and brain biology.  

What treatment is available?

Despite the frequent occurrence of FMD, there are no standardized treatments and this requires more research.  We do know that successful treatment plans must be individualized based on clinical features, and that the earlier the diagnosis is made and treatment is started, the greater likelihood of reversal of the symptoms.  Successful approaches have included physical therapy, psychotherapy and medications such as antidepressants.  We believe in a multidisciplinary approach.  Regardless of the approach, critical to the care plan is clear communication and understanding of the diagnosis by both the healthcare providers and the patients and long term follow-up by the physician. When patients receive the right care symptoms can improve or even resolve.  

Additional information on FMD:

Functional and Dissociative Neurological Symptoms: A Patient's Guide

Functional Neurological Disorders Hope