Functional neurologic disorders — a newer and broader term that includes what some people call conversion disorder — feature nervous system (neurological) symptoms that can't be explained by a neurological disease or other medical condition. However, the symptoms are real and cause significant distress or problems functioning.
Signs and symptoms vary, depending on the type of functional neurologic disorder, and may include specific patterns. Typically these disorders affect your movement or your senses, such as the ability to walk, swallow, see or hear. Symptoms can vary in severity and may come and go or be persistent. However, you can't intentionally produce or control your symptoms.
The cause of functional neurologic disorders is unknown. The condition may be triggered by a neurological disorder or by a reaction to stress or psychological or physical trauma, but that's not always the case. Functional neurologic disorders are related to how the brain functions, rather than damage to the brain's structure (such as from a stroke, multiple sclerosis, infection or injury).
Early diagnosis and treatment, especially education about the condition, can help with recovery.
Symptoms of functional neurologic disorders may vary, depending on the type of functional neurologic disorder, and they're significant enough to cause impairment and warrant medical evaluation. Symptoms can affect body movement and function and the senses.
Signs and symptoms that affect body movement and function may include:
- Weakness or paralysis
- Abnormal movement, such as tremors or difficulty walking
- Loss of balance
- Difficulty swallowing or feeling "a lump in the throat"
- Seizures or episodes of shaking and apparent loss of consciousness (nonepileptic seizures)
- Episodes of unresponsiveness
Signs and symptoms that affect the senses may include:
- Numbness or loss of the touch sensation
- Speech problems, such as inability to speak or slurred speech
- Vision problems, such as double vision or blindness
- Hearing problems or deafness
When to see a doctor
Seek medical attention for signs and symptoms listed above. If the underlying cause is a neurological disease or another medical condition, quick diagnosis and treatment may be important. If the diagnosis is a functional neurologic disorder, treatment may improve the symptoms and help prevent future problems.
The exact cause of functional neurologic disorders is unknown. Theories regarding what happens in the brain to result in symptoms are complex and involve multiple mechanisms that may differ, depending on the type of functional neurologic disorder.
Basically, parts of the brain that control the functioning of your muscles and senses may be involved, even though no disease or abnormality exists.
Symptoms of functional neurologic disorders may appear suddenly after a stressful event, or with emotional or physical trauma. Other triggers may include changes or disruptions in how the brain functions at the structural, cellular or metabolic level. But the trigger for symptoms can't always be identified.
Factors that may increase your risk of functional neurologic disorders include:
- Having a neurological disease or disorder, such as epilepsy, migraines or a movement disorder
- Recent significant stress or emotional or physical trauma
- Having a mental health condition, such as a mood or anxiety disorder, dissociative disorder or certain personality disorders
- Having a family member with a functional neurologic disorder
- Possibly, having a history of physical or sexual abuse or neglect in childhood
Women may be more likely than men to develop functional neurologic disorders.
Some symptoms of functional neurologic disorders, particularly if not treated, can result in substantial disability and poor quality of life, similar to that caused by medical conditions or disease.