According to data from the Spanish Society of Neurology (SEN), in our country between 0.2-2% of the population suffers from some type of functional neurological disorder. In fact, about 10% of movement disorder cases correspond to a functional movement disorder. Despite being quite frequent, they are still very unknown and their clinical management is complicated, even by professionals. For this reason, the SEN has just published the “Manual of Recommendations for the Diagnosis and Treatment of Functional Movement Disorders”.
To better understand these disorders, we answer some of the most frequently asked questions.
What is a functional movement disorder?
A functional neurological disorder (TNF) is one Neurological disorder for which an organic cause is not found to explain the symptoms suffered by the patient, that is, when the relevant tests are carried out, no known neurological alterations or diseases that cause these symptoms are found. When this disorder causes movement problems, such as tremors, dystonia (involuntary contractions), slow movement, etc., we would be talking about functional movement disorders (FMD). The fact that the medical tests are normal creates many difficulties in finding a diagnosis, which in turn generates an uncertainty that causes greater anguish in the patient that worsens the physical and psychological symptoms.
What disorders or symptoms are the most common?
The patient with TMF can present with any known movement disorder or a combination of several of them. In fact, 74% of patients present at least two symptoms together.
• The most common is temblor, which affects more than half of people with TMF. It usually affects the hands and arms (not the fingers), and is also present in the head, trunk and legs.
• Another very frequent is distonía, which are involuntary movements or abnormal postures due to sustained or intermittent muscle contractions. Among functional dystonias we find the cranial one (which occurs on the face and can affect the face, eyes, jaw, tongue and palate, and can be divided into facial or oculomotor); the fixed (they are painful and affect several limbs) and the paroxysmal (combination of abnormal movements with dystonic postures).
•Functional gait disorders, that is, they have difficulties when walking, whether in terms of speed, cadence, Korea…. They are quite frequent, since they appear in more than 40% of people with FMD.
•Mioclonías. Intermittent random short jerks (less than 100 milliseconds) consisting of a brief muscle contraction and a return to the original position.
• Less frequent is the Functional Parkinsonism, a TMF that shares symptoms with Parkinson’s, such as tremor, gait disturbance, or stiffness, but who do not have the disease.
What causes them?
Since they are not due to any known neurological disease, I do not know what causes these FMDs, but I do know what can trigger, precipitate them or what factors can predispose them to suffer them. Although it depends on each disorder and, above all, on each patient, it is known that, in general, They usually occur after having suffered stressful life events, panic attacks, trauma, infectious diseases … or there are certain personality types that are more prone to them. In addition, it is also common for FMT to be associated with another type of neurological disorder, since between 10-15% of patients have an associated neurological disease.
Who are affected?
Functional movement disorders most commonly affect young adults, the elderly and children from the age of 10, since less than 13% present them before that age. Although they are quite unknown, they have a high prevalence in Neurology consultations, since up to 9% of consultations with neurologists have been for this reason, and in specialized consultations for Movement Disorders they can account for up to 20% of the cases evaluated. What’s more, functional movement disorders are among the most common causes of neurological disability; since in addition to a movement disorder, up to 76% of patients have pain in the affected area, 50% of them with severe and extreme pain.
If there is no disease behind, does it mean that its cause is psychological?
Although at first, not finding an adequate biological cause and having as triggers sometimes stressful episodes, they were classified as stress or emotional disorders, the truth is that the current view of TNFs is broader than the purely psychological. Furthermore, the fact that there is currently no cause biological, It does not mean that it does not exist and will not be found in a few years, because until relatively recently diseases such as epilepsy or migraine were classified as functional. Even so, there is still the belief that TNFs are not “real” or that patients are simulating, which sometimes leads these patients to wander between Neurology and Psychiatry services without either providing a solution.
At present, research continues and there are more and more studies and scientific publications on the origin of FMT in which professionals from various disciplines participate jointly, from neurologists, to psychiatrists, through psychologists or physiotherapists. Thus, to this day, It is postulated that there are both biological and psychological actors involved in its development, which has conditioned a change in the paradigm of management of these disorders.
How are they treated and what is the prognosis?
There are still no official protocols for the treatment of FMT, but there are there are combined treatments that are proving effective, such as psychological therapy, physical rehabilitation or pharmacotherapy (mainly antidepressants), in addition to other techniques such as hypnosis. For this reason, it is increasingly clear that the approach must be multidisciplinary, that is, it must be treated from different areas, covering both the socio-psychological aspects and those derived from motor rehabilitation. The problem is that there are still very few centers that offer them worldwide.
As long as these treatments are standardized and given that in many cases the diagnosis is complicated and takes a long time, the prognosis is usually not favorable. Motor problems are usually only solved in 20% of cases and in the majority the discomfort continues and even causes high rates of disability.