Functional neurological disorder (FND) is a complex condition characterised by neurological symptoms that are not explained by a traditional structural disease, such as stroke, multiple sclerosis, or epilepsy. Instead, the symptoms are related to a functional problem in the way the brain receives and sends signals to the body, rather than being caused by identifiable damage or abnormalities in brain structure. This disruption in communication within the nervous system leads to real, often disabling, symptoms that can affect movement, sensation, and thinking.
FND can be difficult to understand because it sits at the intersection of neurology and psychiatry. Historically referred to as “conversion disorder” or “hysteria”, the modern understanding of FND recognises it as a neurological condition with genuine symptoms, not imagined or feigned. Individuals with FND can experience a range of disabling manifestations, including seizures, weakness, tremors, or sensory loss, and often face challenges in receiving an accurate diagnosis due to the complex nature of the disorder.
The causes of FND are not completely understood, but it is believed to arise from a combination of biological, psychological, and social factors. Many patients report that their symptoms began or worsened after a period of stress, trauma, physical injury, or illness, though in some cases no clear trigger is identified. Rather than being caused by damage to the nervous system, FND involves abnormalities in brain function. Functional neuroimaging studies have demonstrated that brain areas involved in attention, emotion regulation, and self-agency show altered activity in people with FND, offering insights into possible mechanisms behind the disorder.
Recognising the distinction between functional symptoms and those caused by diseases such as multiple sclerosis or epilepsy is critical for an accurate diagnosis. Unlike conditions with structural brain changes, FND relies on identifying positive signs during neurological examination, such as inconsistencies in symptoms or the presence of “Hoover’s sign” in cases of leg weakness. Early and confident diagnosis, supported by neurologists familiar with the condition, is key to helping patients understand their condition and begin appropriate treatment plans.
Motor symptoms and movement-related issues
Motor symptoms are among the most recognisable features of functional neurological disorder (FND), often forming a key part of both the presentation and the diagnosis. People with FND can experience a wide range of movement-related issues, which may include weakness or paralysis of a limb, tremors, abnormal gait, jerky movements, or muscle stiffness. These disturbances can affect one or more body parts and may come on suddenly. Unlike neurological conditions caused by structural lesions, such as those resulting from a stroke, these symptoms are not due to any detectable damage but are instead a dysfunction in the way the brain sends and interprets signals.
A common manifestation in FND is functional limb weakness, which often presents in a variable and inconsistent manner. For example, a person may struggle to lift their arm during a clinical test but find they can gesture freely while speaking without awareness of the improved movement. This variability is a hallmark characteristic of FND and plays an essential role in differentiating it from other causes of neurological symptoms. Similarly, functional tremors may have an irregular pattern and can reduce or stop when the person is distracted or engaged in a simultaneous action that requires concentration.
Problems with walking, sometimes described as a functional gait disorder, are also typical. Individuals might drag a foot, walk with exaggerated movements, or exhibit sudden freezing. These gait patterns often look dramatically different from those caused by neurological diseases such as Parkinson’s or multiple sclerosis. Despite the disconcerting appearance of these symptoms, the underlying problem lies in functional connections in the brain rather than disease or injury of nerves or muscles.
Additionally, some individuals may exhibit abnormal postures or movements, such as dystonia or seizures that resemble epileptic episodes but are not accompanied by the electrical changes seen in epilepsy. These are termed functional seizures or non-epileptic attacks and are increasingly recognised as part of the spectrum of FND symptoms. Diagnosis is not based on ruling out all other conditions, but instead relies on identifying these positive clinical signs that are characteristic of FND through a detailed neurological examination conducted by a skilled clinician.
Motor symptoms in FND can be distressing and disabling, significantly affecting a person’s daily activities and independence. Understanding that these symptoms arise from altered brain function rather than structural damage is key to directing appropriate treatment—an approach focused on retraining the brain and nervous system. With the right diagnosis and management strategies, many individuals can experience improvement in function, although the recovery journey may vary widely between patients.
Sensory disturbances and perceptual changes
Sensory disturbances are another common and often troubling feature of functional neurological disorder (FND). Individuals with FND may report a range of abnormal sensations, which can include numbness, tingling, burning or crawling feelings on the skin. These sensations are often described as shifting or inconsistent in nature and may not follow the typical patterns of nerve damage seen in other neurological conditions, such as peripheral neuropathy or multiple sclerosis. The altered perception experienced by individuals with FND is real and distressing, originating from disrupted functional processing in the brain rather than damage to sensory pathways themselves.
Loss of sensation or functional sensory loss can affect one or more parts of the body and often presents in ways that defy anatomical norms. For example, a person may report numbness in an entire limb or side of the body in a distribution that does not correspond to known nerve or spinal cord segments. These sensory symptoms can be debilitating and contribute to difficulties in coordination, balance, and daily functioning. Importantly, they reflect a genuine problem in brain function, and not psychogenic malingering or deliberate fabrication, as was once falsely assumed.
Visual disturbances are also frequently noted in individuals with FND. These can include blurred vision, double vision, or even episodes of functional blindness where visual input is intact, but the brain fails to process it appropriately. Such symptoms can arise suddenly and may fluctuate depending on stress levels or other environmental factors. Similarly, changes in hearing – such as a feeling of deafness or muffled sounds – have been reported by some patients, despite normal audiometry results, reinforcing the functional, rather than structural, basis for these experiences.
Disturbances in spatial awareness and sense of the body, sometimes referred to as altered body perception, are increasingly recognised as part of the FND symptom profile. These can involve feelings of detachment from one’s limbs, a sense that a body part does not belong to them, or distortions in body size or position – symptoms that can occur in the absence of any identifiable neurological damage. Such perceptual changes highlight the complexity of how the brain integrates sensory information and suggests a breakdown in the normal processing that supports body awareness and sensory integration.
Diagnosis of sensory symptoms within the context of functional neurological disorder involves careful neurological assessment, with attention to key clinical signs that differentiate functional from structural causes. Patterns such as a sensory deficit that improves when the patient is distracted, or inconsistent test results during examination, point towards a functional origin. Clinicians may also use specific bedside tests to support the diagnosis, such as determining whether tactile sensation is altered differently in varying positions. These signs not only help confirm the diagnosis of FND but are crucial in communicating to the patient that their symptoms are genuine and amenable to treatment.
Sensory and perceptual disturbances in FND can be frightening and isolating for those affected, especially when initial medical investigations fail to provide a clear explanation. Understanding that these symptoms stem from a functional disruption – rather than an invisible disease – allows for targeted therapeutic approaches that aim to normalise sensory processing. Approaches such as sensory retraining, physiotherapy, and psychological support often play a role in helping individuals regain function and reduce the impact of these symptoms on daily life.
Cognitive and emotional symptoms
Cognitive and emotional symptoms are a significant aspect of functional neurological disorder (FND) and can be as disabling as the motor or sensory complaints. Many individuals with FND report issues with memory, concentration, and general mental clarity—commonly referred to as “brain fog.” These cognitive difficulties are not the result of structural brain damage but stem from the same disrupted neural networks that affect movement and sensation. People frequently describe challenges in following conversations, remembering details, or maintaining focus, particularly when they are fatigued or under stress. These symptoms can fluctuate in severity and are often exacerbated by anxiety or physical illness.
Functional cognitive symptoms may mimic those seen in early dementia or other neurological conditions, but the underlying mechanisms differ. In FND, cognitive symptoms often show inconsistency: for instance, individuals may perform well on formal cognitive tests under structured conditions but struggle with similar tasks in everyday life. This discrepancy is an important diagnostic clue and should be carefully explored during assessment to avoid misdiagnosis. Clinicians look for patterns that suggest a functional origin, such as improvement during distraction and disproportionate impact of stress and fatigue on cognition.
Emotional symptoms are closely intertwined with the cognitive aspects of FND and can present as anxiety, depression, mood swings, or emotional numbness. These emotional changes are not simply secondary reactions to physical symptoms, but integral components of the condition itself. Altered brain activity in areas responsible for emotion regulation, such as the amygdala and prefrontal cortex, may contribute to emotional dysregulation seen in FND. Individuals may find that their mood shifts rapidly, or that they experience heightened emotional responses to relatively minor triggers, which can interfere significantly with social interactions and daily activities.
In some cases, alexithymia – difficulty in identifying or expressing emotions – may be present, further complicating the clinical picture. Emotional shutdown, detachment, or blunting of affect may be experienced alongside more visible symptoms like seizures or movement abnormalities. People may have trouble connecting their emotional state to their physical symptoms, though research indicates this interplay contributes to the onset and maintenance of the disorder. It’s important to approach these symptoms with compassion and understanding, as patients often fear being misunderstood or mislabelled when emotional components of their condition are discussed.
Psychological comorbidities, including trauma-related conditions such as post-traumatic stress disorder (PTSD), are more common in those with FND compared to the general population. However, the presence of emotional or psychological distress should not detract from the validity of the neurological symptoms. The diagnosis of functional neurological disorder is based not on excluding psychiatric causes, but on identifying positive clinical signs that confirm the diagnosis. This includes observing how cognitive symptoms behave under examination, and how they interact with other features of the disorder.
Effective treatment for cognitive and emotional symptoms in FND is typically multidisciplinary and may involve cognitive-behavioural therapy, education about the disorder, and cognitive rehabilitation strategies tailored to the individual. Understanding the functional basis of their symptoms often brings relief to patients, helping them to reframe their experiences and engage with supportive therapies. As with other aspects of FND, early diagnosis and appropriate communication can greatly assist in the path to recovery, especially when emotional and cognitive symptoms are addressed openly and empathetically.
Diagnosis and approaches to management
The diagnosis of functional neurological disorder (FND) involves identifying specific clinical features that distinguish it from other neurological conditions. Rather than relying purely on excluding diseases through imaging or laboratory testing, healthcare professionals look for ‘positive signs’ during examination that are characteristic of FND. These may include inconsistency in symptom presentation, or physical signs that improve with distraction. For example, in cases of functional limb weakness, a neurologist might observe improved strength when a patient is not consciously trying to move, which helps confirm the diagnosis. The use of such identifiable criteria enables clinicians to make a definitive and confident diagnosis, moving away from outdated ideas that required ruling out every other possibility first.
Functional symptoms are genuine health experiences that are distressing and disruptive to daily life, yet they arise from abnormal functioning in the brain’s processing systems rather than from disease or damage. Given the complexity of the condition, a multidisciplinary approach to management is often the most effective way forward. An early and accurate diagnosis, delivered with clear and empathetic communication, plays a vital role in improving outcomes. It helps to establish patient trust and encourages engagement with therapeutic strategies aimed at neurological retraining and emotional support. When individuals understand that their symptoms result from brain function rather than structural damage, it can be the first step toward meaningful recovery.
Physiotherapy is considered a cornerstone of treatment, particularly for motor and functional movement symptoms. Specialist physiotherapists trained in managing FND use specific techniques to promote normal patterns of movement and reduce maladaptive responses. Therapy might include graded activity plans, exercises to improve balance and coordination, or task-specific retraining. The focus is not just on the physical aspects of movement, but also on rebuilding the brain’s confidence in automatic motor control, which is often disrupted in FND. Treatment sessions are tailored to each individual, with attention given to pacing and avoiding overexertion that could worsen fatigue or symptoms.
Psychological therapies, especially cognitive behavioural therapy (CBT), are often recommended as part of the treatment plan. These approaches help individuals understand the mind-body relationship involved in FND, explore potential stressors or behavioural patterns that may exacerbate symptoms, and develop strategies for coping with both cognitive and emotional challenges. Importantly, therapy is not directed at suggesting symptoms are “all in the mind”, but rather as a pathway to optimising brain function and managing the varied symptoms associated with the disorder. For individuals with coexisting mental health conditions such as anxiety, depression, or past trauma, psychological therapy can address these aspects directly and holistically.
Occupational therapy can also be pivotal, especially for those whose symptoms interfere with daily tasks, routines, or employment. Therapists work with patients to modify activity levels, plan sustainable routines, and improve independence at home or in the workplace. Sleep hygiene, nutrition, and sensory strategies may also be incorporated to support recovery. Education about FND as a diagnosis is central to these therapies, helping patients and families to understand the nature of the condition and reduce feelings of fear or uncertainty surrounding the symptoms.
For some, functional seizures (also known as dissociative seizures or non-epileptic attack disorder) are a central part of their FND presentation. Management of these episodes often involves collaboration between neurology, clinical psychology and sometimes psychiatry teams. Individuals are taught techniques for recognising and managing early warning signs, implementing grounding strategies, and reducing the triggers or behaviours that may sustain the cycle of seizures. Support groups and peer forums can also offer valuable networks for sharing experiences and coping advice.
While medications are not a primary treatment for FND itself, they may be appropriate in addressing accompanying symptoms such as chronic pain, sleep disturbances, or mood disorders. However, careful prescribing is necessary to avoid medications that might inadvertently worsen symptoms or add unnecessary side effects. Instead, the emphasis is placed on active therapies that encourage neuroplasticity—the brain’s capacity to rewire and improve function over time. With time, education, and the correct multidisciplinary input, many patients report meaningful improvements in their ability to manage symptoms and return to valued activities.
