10 Common Symptoms of Functional Neurological Disorder (Conversion Disorder)

Functional neurological disorder (FND), also referred to as conversion disorder, is a condition where patients experience neurological symptoms that cannot be explained by a structural neurological disease or other medical condition. The symptoms are real and can cause significant distress and disability, affecting how the brain sends and receives signals rather than being caused by structural damage to the nervous system itself.

Understanding the symptoms of FND is crucial for early recognition and proper diagnosis. This condition can affect people of all ages and may develop suddenly following a stressful event or gradually over time. The symptoms can vary widely from person to person and may change in severity or type over time.

1. Weakness or Paralysis

One of the most common symptoms of functional neurological disorder is muscle weakness or paralysis that cannot be explained by typical neurological diseases. This weakness may affect one or more limbs and can range from mild weakness to complete paralysis.

Patients may experience:

• Sudden onset of weakness in arms or legs
• Difficulty lifting limbs or maintaining grip strength
• Dragging of one leg while walking
• Inability to move certain body parts despite no structural damage

The weakness in FND often has distinctive features that differ from weakness caused by structural neurological conditions. It may be inconsistent, varying with attention and distraction, and may not follow typical patterns seen in stroke or other neurological diseases. The affected limb may feel heavy or difficult to control, and the weakness may improve when the person is distracted or during certain activities.

2. Abnormal Movements

Functional movement disorders are a prominent feature of FND and can manifest in various ways. These movements are involuntary but differ from those seen in conditions like Parkinson’s disease or essential tremor.

Common abnormal movements include:

• Tremors that may affect hands, arms, legs, or head
• Jerky or spasmodic movements
• Dystonia-like postures (sustained muscle contractions)
• Myoclonus (sudden, brief jerking movements)
• Gait abnormalities with unusual walking patterns

These movements often have characteristics that help distinguish them from organic movement disorders. They may be distractible, meaning they change or disappear when the person’s attention is diverted. The tremor may vary in amplitude and frequency, and movements may be suggestible or entrainable to external rhythms.

3. Seizure-Like Episodes (Non-Epileptic Seizures)

Functional seizures, also called psychogenic non-epileptic seizures (PNES) or dissociative seizures, are episodes that resemble epileptic seizures but are not caused by abnormal electrical activity in the brain. These episodes can be frightening and may be difficult to distinguish from epileptic seizures without proper medical evaluation.

Characteristics of functional seizures may include:

• Episodes of unresponsiveness or altered awareness
• Convulsive movements or shaking
• Episodes lasting longer than typical epileptic seizures
• Side-to-side head movements
• Eyes closed during the episode (unlike most epileptic seizures)
• Crying or talking during episodes
• Gradual onset and offset rather than sudden

These seizures can occur multiple times daily or infrequently, and their duration can vary significantly. Proper diagnosis requires video-EEG monitoring to confirm the absence of epileptic activity during episodes.

4. Sensory Symptoms

Altered sensation is a frequent complaint in patients with functional neurological disorder. These sensory changes can significantly impact daily activities and quality of life.

Sensory symptoms may include:

• Numbness or tingling in limbs or face
• Complete loss of sensation in specific body areas
• Altered pain perception
• Heightened sensitivity to touch
• Sensation of pins and needles
• Feeling of tightness or constriction

The pattern of sensory loss in FND may not correspond to known anatomical distributions of nerves or dermatomes. For example, sensory loss might affect an entire limb in a “stocking” or “glove” pattern that doesn’t match typical nerve distributions. The sensory symptoms may also be inconsistent during examination and can vary depending on how the examination is performed.

5. Speech and Swallowing Difficulties

Functional speech and swallowing problems can significantly affect communication and nutrition. These symptoms can be particularly distressing and may lead to social isolation or nutritional concerns.

Common manifestations include:

• Dysphonia (difficulty producing voice or hoarseness)
• Aphonia (complete loss of voice or whispering speech)
• Slurred speech or difficulty articulating words
• Stuttering or stammering
• Difficulty swallowing (functional dysphagia)
• Sensation of a lump in the throat (globus sensation)

The speech difficulties in FND may be intermittent and can sometimes improve during certain activities like singing, coughing, or when distracted. Functional dysphagia may cause genuine difficulty swallowing, but medical examination typically shows no structural abnormality of the throat or esophagus.

6. Visual Disturbances

Visual symptoms are another manifestation of functional neurological disorder, ranging from mild visual changes to complete vision loss. These symptoms can be unilateral (affecting one eye) or bilateral (affecting both eyes).

Visual disturbances may present as:

• Blurred or double vision
• Partial or complete vision loss
• Tunnel vision (narrowed visual field)
• Visual hallucinations
• Difficulty focusing
• Light sensitivity

Functional visual loss often has distinctive features on examination. The visual fields may show tubular or spiral patterns that don’t match organic eye diseases. Patients may be able to navigate obstacles despite claiming complete vision loss, and pupillary reflexes remain normal. Ophthalmologic and neurological examinations typically reveal no structural abnormalities that would explain the visual symptoms.

7. Cognitive Symptoms

Many individuals with FND experience cognitive difficulties that can affect their ability to work, study, or perform daily activities. These symptoms are sometimes referred to as “functional cognitive disorder” or “dissociative amnesia” when severe.

Cognitive symptoms include:

• Memory problems, particularly short-term memory
• Difficulty concentrating or maintaining attention
• Mental fog or confusion
• Slowed thinking or processing speed
• Difficulty finding words
• Problems with executive function and decision-making

These cognitive difficulties often worsen with stress or fatigue. The pattern of cognitive impairment may not match typical dementia or other neurodegenerative conditions. Neuropsychological testing may show inconsistent performance or patterns that suggest functional rather than organic causes.

8. Fatigue and Sleep Disturbances

Persistent fatigue is an extremely common and debilitating symptom in functional neurological disorder. This fatigue is often severe and doesn’t improve significantly with rest.

Fatigue-related symptoms include:

• Overwhelming physical exhaustion
• Mental fatigue and reduced cognitive stamina
• Post-exertional malaise (worsening symptoms after activity)
• Unrefreshing sleep
• Insomnia or difficulty maintaining sleep
• Hypersomnia (excessive sleepiness)
• Disrupted sleep-wake cycles

The fatigue in FND can be so severe that it prevents individuals from carrying out normal daily activities. It may fluctuate throughout the day and can be worsened by physical or mental exertion, stress, or poor sleep quality. Many patients report that their sleep is not restorative, waking up feeling as tired as when they went to bed.

9. Pain Symptoms

Chronic pain is frequently reported by patients with functional neurological disorder and can occur in various body regions without identifiable organic cause. This pain is genuine and can be severe and disabling.

Pain presentations in FND include:

• Chronic headaches or migraines
• Widespread body pain
• Limb pain without clear cause
• Chest pain
• Abdominal pain
• Back and neck pain
• Joint pain

The pain associated with FND may not follow typical anatomical patterns and can migrate from one body area to another. It may be constant or intermittent, and its intensity can vary significantly. The pain often persists despite normal medical investigations and may not respond to typical pain medications in expected ways.

10. Dizziness and Balance Problems

Dizziness and difficulties with balance and coordination are common in FND and can significantly increase the risk of falls and limit mobility.

Balance and dizziness symptoms include:

• Persistent dizziness or lightheadedness
• Feeling unsteady or off-balance
• Vertigo (spinning sensation)
• Difficulty walking in a straight line
• Feeling like the floor is moving
• Increased risk of falls
• Need for walking aids or support

The balance difficulties in FND may appear excessive relative to objective findings on examination. Patients may sway dramatically during balance testing but rarely fall, and may show excessive slowness or hesitation with movements. The dizziness may be constant or triggered by specific situations or movements, and vestibular testing typically shows no abnormalities that would explain the severity of symptoms.

Main Causes and Risk Factors

While the exact mechanisms underlying functional neurological disorder are not fully understood, research suggests it involves a problem with how the brain sends and receives signals rather than structural damage. Several factors may contribute to the development of FND:

Psychological Stressors: Many patients report experiencing significant psychological stress before symptom onset, including traumatic events, emotional conflicts, or major life changes. However, not all individuals with FND can identify a specific trigger.

Previous Trauma: A history of physical, emotional, or sexual trauma, particularly during childhood, appears to be more common in individuals with FND. However, trauma is not present in all cases, and FND should not be assumed to be purely psychological.

Other Medical Conditions: Having another neurological condition or experiencing a physical injury may sometimes trigger functional neurological symptoms. Some patients develop FND following concussion, surgery, or other medical events.

Mental Health Conditions: Depression, anxiety, post-traumatic stress disorder (PTSD), and other mental health conditions are commonly associated with FND, though they are not always present.

Predisposing Factors: Certain personality traits, coping styles, and previous illness experiences may make some individuals more susceptible to developing FND. Women are diagnosed with FND more frequently than men, though the condition affects all genders.

Neurobiological Factors: Modern neuroimaging studies suggest that FND involves altered brain network function, particularly in areas responsible for voluntary movement, attention, emotion processing, and self-awareness. This represents a genuine neurological problem, even though structural scans appear normal.

Frequently Asked Questions

Is functional neurological disorder a real medical condition?

Yes, FND is a genuine medical condition recognized by neurologists and psychiatrists worldwide. The symptoms are real and not imagined or faked. Modern research shows that FND involves alterations in brain function, even though standard brain imaging appears normal.

How is FND diagnosed?

FND diagnosis is made by a neurologist based on positive clinical findings during examination, not just by excluding other conditions. The diagnosis involves identifying characteristic features of functional symptoms and using specific examination techniques. Additional tests like EEG, MRI, or blood work may be performed to rule out other neurological conditions.

Can functional neurological disorder be cured?

Many people with FND can improve significantly with appropriate treatment, though recovery varies among individuals. Treatment typically involves physical therapy, occupational therapy, psychotherapy, and patient education about the condition. Some patients recover completely, while others experience improvement in symptoms and function even if symptoms don’t disappear entirely.

Is FND the same as conversion disorder?

Yes, FND and conversion disorder refer to the same condition. “Functional neurological disorder” is the preferred term among neurologists, while “conversion disorder” is the psychiatric diagnostic term. The terminology has evolved to better reflect current understanding of the condition as a neurological problem.

Are FND symptoms psychological or physical?

FND symptoms are both neurological and can be influenced by psychological factors. This is not an “either/or” situation. The symptoms arise from a problem with brain function (how the nervous system works) rather than brain structure (damage to the nervous system). Psychological factors may contribute to the condition, but FND is a genuine neurological disorder.

Can stress make FND symptoms worse?

Yes, stress commonly exacerbates FND symptoms. Many patients notice that their symptoms worsen during periods of increased physical or emotional stress and may improve when stress is reduced. However, stress is not the sole cause of FND, and symptom management involves more than just stress reduction.

Is FND a rare condition?

No, FND is relatively common. It is one of the most frequent reasons for neurology consultations, accounting for approximately 5-10% of neurology outpatient visits. FND is about as common as multiple sclerosis or Parkinson’s disease in neurology clinics.

Can children develop functional neurological disorder?

Yes, FND can affect children and adolescents as well as adults. The symptoms and presentation may be similar to adults, though the approach to diagnosis and management may need to be adapted for younger patients. Early recognition and appropriate intervention are important for better outcomes in pediatric cases.

References:

• Mayo Clinic – Conversion Disorder (Functional Neurological Disorder)
• National Institute of Neurological Disorders and Stroke – Functional Neurologic Disorder
• Neurosymptoms.org – FND Information Guide
• NHS – Functional Neurological Disorder
• Johns Hopkins Medicine – Conversion Disorder