Functional neurological disorders (FND)

FNDs manifest themselves through a wide variety of symptoms, affecting both voluntary motor skills and sensory functions. These symptoms are often fluctuating, appearing suddenly or evolving intermittently. The most common disorders involve movement. Some people experience muscle weakness or paralysis, without any detectable damage to the nerves or muscles. Others experience tremors, uncontrollable shaking, or dystonia (involuntary and prolonged muscle contractions), leading to abnormal postures or unusual movements. Gait may also become unstable or clumsy, with no apparent cause visible on examination.

Symptoms may also affect the body's sensitivity. Some people experience anesthesia, i.e., loss of sensation in part of the body, or paresthesia, strange sensations such as tingling, numbness, or pins and needles, without any medical explanation.

Speech disorders (difficulty speaking or altered voice), vision problems (double or blurred vision), or temporary hearing loss may also occur. Some patients report cognitive disorders, such as difficulty concentrating, memorizing, or organizing their thoughts, even though brain tests show no abnormalities.

Finally, a particular type of symptom is psychogenic non-epileptic seizures: these are episodes resembling epileptic seizures (loss of consciousness, involuntary movements), but without abnormal electrical activity in the brain. These seizures are not simulated and can be very disruptive to daily life.

These symptoms can significantly interfere with daily life, limiting independence and affecting quality of life in the same way as other recognized neurological diseases.

The exact origin of NFTs is still poorly understood, and is multifactorial. Contrary to popular belief, the symptoms are neither imaginary nor feigned. They are genuine neurological disorders, often associated with abnormalities in the processing of information by certain brain regions involved in emotion regulation, attention and motor control. Some neurocognitive models propose that symptoms emerge from a failure of voluntary motor control or altered sensory processing. These mechanisms may be reinforced by body-directed attention processes, false expectations, or hypersensitivity to stress.

In addition, a triggering event is frequently reported, such as physical trauma, intense emotional stress, or acute illness. However, in around half of all cases, no obvious triggering factor is identified.

A history of psychiatric disorders (anxiety, depression, dissociative disorders) or early trauma (childhood abuse or neglect) is also frequently found, though not systematically.

The development of a functional neurological disorder may be favored by a multitude of risk factors. Although no single profile can predict the onset of the disorder with certainty, certain individual predispositions are repeatedly observed in clinical studies.

A history of neurological disease, such as epilepsy or migraines, seems to favour the onset of functional disorders. Similarly, physical trauma, injury or even surgery can act as a trigger, disrupting the nerve circuits involved in body perception and motor control. In many patients, these episodes can be perceived as a catalyst, without the person being aware of the link between the event and the symptoms.

A history of mental disorders also plays a significant role. Anxiety, depression or dissociative disorders, sometimes present since childhood, are factors of vulnerability. Early exposure to situations of abuse, neglect or prolonged stress was also noted in a significant proportion of cases. However, more than half of patients have no identifiable psychological factor, highlighting the multifactorial complexity of the disorder.

Women seem to be more frequently affected than men, although the difference tends to diminish at the latter stages of life.

Traditionally, the diagnosis of NFTs was based on a process of systematic exclusion: symptoms were considered “unexplained” only after any underlying pathology had been methodically ruled out. This approach has given way to a more structured method, based on positive criteria. Today, clinicians focus on detecting specific clinical signs that can be observed on examination, and which can directly identify a functional disorder.
These signs do not come from brain imaging or conventional biological tests, which generally remain normal. Rather, they are abnormalities in motor or sensory performance, which fluctuate, are inconsistent with known neurological anatomy, or diminish when the patient's attention is diverted. This “variability” is a fundamental marker of positive diagnosis.
Functional neuroimaging has documented alterations in the functioning of brain circuits involved in motor control, attention, self-awareness and emotional regulation. These results support the idea that dysfunction is real, even in the absence of anatomical lesions, and underline the fact that this is a disease in its own right.

Diagnosis is generally based on the joint expertise of a neurologist and, depending on the case, a psychiatrist or specialized psychologist.

The treatment of functional neurological disorders is based on a multidisciplinary, personalized and progressive approach. It is not a single treatment, but a structured care pathway combining therapeutic education, functional rehabilitation and, if necessary, psychological support.

The first essential step in treatment is for the patient to understand the diagnosis. Explaining that symptoms are real, that they are not imagined or feigned, and that they result from a disturbance in brain function, represents a therapeutic lever in its own right. It often leads to an initial improvement in symptoms, and paves the way for active collaboration with caregivers.

Depending on the clinical manifestations, rehabilitative approaches are preferred. Physiotherapy and occupational therapy target motor disorders such as paralysis or gait disorders, using specific techniques that exploit cerebral plasticity. For dissociative crises, psychotherapy, particularly cognitive-behavioral approaches, is particularly indicated. These interventions aim to restore the perception of control over movements and desensitize the emotional or bodily responses associated with symptoms.

In some cases, drug treatments may be proposed, not for the TNF itself, but to treat associated disorders such as anxiety or depression. The involvement of a multidisciplinary team is often the key to lasting improvement.

The evolution of a functional neurological disorder is often unpredictable. Some patients experience a significant reduction in their symptoms, or even no symptoms at all, while others suffer long-lasting sequelae. Several factors influence this trajectory, including the time between onset of symptoms and diagnosis, and adherence to the proposed treatment.

In people who are treated early, significant improvement is common. Conversely, when the disorder takes hold over time, complications can arise, such as loss of autonomy, reduced quality of life and social isolation. It is not uncommon for chronic pain, persistent fatigue or cognitive problems such as difficulty concentrating to be added to the initial symptoms.

A well-documented aggravating factor is a lack of awareness of the disorder, both on the part of patients and certain professionals. Repeated medical examinations, the absence of a clear explanation or doubts expressed about the veracity of symptoms can accentuate anxiety, reinforce symptoms and complicate remission.

There is no reliable way of preventing the onset of NFTs, as the exact causes remain complex and vary from one individual to another. However, certain measures can reduce the risks or limit the intensity of symptoms.
Learning to manage stress on a daily basis, expressing emotions in a safe environment, or maintaining a balanced lifestyle (sleep, diet, physical activity) can play a protective role.
Finally, prevention also involves early recognition of symptoms. Anyone noticing unexplained weakness, tremors or sudden loss of sensation should not hesitate to seek medical advice. Early diagnosis often leads to a more favorable outcome.

It's important to consult a healthcare professional as soon as any unusual symptom appears, especially if it interferes with daily activities. These may include:

• Sudden weakness in a limb.
• Unexplained tremors.
• A seizure resembling an epileptic fit.
• Feeling unwell
• Difficulty speaking or swallowing.
• Abnormal sensations in the body (numbness, tingling, etc.).

Even if these symptoms can't be explained by a disease visible on tests, they must be taken seriously. The sooner the diagnosis is made, the greater the chances of recovery.
It's important not to wait until the condition becomes chronic before talking about it. If the diagnosis of TNF is confirmed, appropriate treatment can improve symptoms and prevent them from worsening.

At Hôpital de La Tour, patients with functional neurological disorders benefit from a multidisciplinary, coordinated, person-centred approach. This approach is based on the complementary skills of neurologists, psychologists, physiotherapists and specialized nurses.

The treatment process often begins with a specialized neurological consultation, which provides a clear and reassuring diagnosis. Once the disorder has been identified, a personalized treatment plan is drawn up with the patient. The aim is to restore the patient's function and autonomy, making the most of his or her personal resources, while avoiding unnecessary tests or the chronicization of symptoms.

Is a functional neurological disorder a mental illness?
No. It's a disorder of brain function, situated at the interface between neurology and psychiatry. The symptoms are real, not simulated, and often very disabling.

Can it be cured?
Yes, many patients improve or even recover, especially when diagnosed early and treated appropriately.

How can TNF be distinguished from classic neurological disease?
Functional neurological disorders are distinguished by the absence of visible lesions on examination (MRI, EEG). Diagnosis is based on specific clinical signs, such as a variation in symptoms depending on the context, or their transient disappearance when distracted. Unlike a lesion-based pathology, the brain “malfunctions” but is not damaged.

What are the first signs of a functional neurological disorder?
Initial symptoms may include muscle weakness, tremors, slurred speech or seizures with no electrical abnormalities. Some patients experience numbness, blurred vision or memory loss. These symptoms can be sudden or gradual.

Are medical examinations always normal?
Generally speaking, yes. Cerebral imaging or conventional neurological tests are normal, but this does not invalidate the symptoms.

Is it a chronic disorder?
It can be, but it doesn't have to be. With the right support, it can evolve favorably.

Does stress play a role?
Often, but not always. Stress or trauma can trigger symptoms, but this is not an absolute rule.

Who should I talk to if I think I have TNF?
The first point of contact is often your GP. He or she may refer you to a neurologist, who will confirm the diagnosis on the basis of specific clinical signs. Depending on the case, treatment by a psychologist, psychiatrist or specialized physiotherapist may complete the care pathway.