Conversion disorder (CD), or functional neurologic symptom disorder, is a diagnostic category used in some psychiatric classification systems. It is sometimes applied to patients who present with neurological symptoms, such as numbness, blindness, paralysis, or fits, which are not consistent with a well-established organic cause, which cause significant distress, and can be traced back to a psychological trigger. It is thought that these symptoms arise in response to stressful situations affecting a patient's mental health or an ongoing mental health condition such as depression. Conversion disorder was retained in DSM-5, but given the subtitle functional neurological symptom disorder. The new criteria cover the same range of symptoms, but remove the requirements for a psychological stressor to be present and for feigning to be disproved. ICD-10 classifies conversion disorder as a dissociative disorder while DSM-IV classifies it as a somatoform disorder. Signs and symptoms Conversion disorder begins with some stressor, trauma, or psychological distress. Usually the physical symptoms of the syndrome affect the senses or movement. Common symptoms include blindness, partial or total paralysis, inability to speak, deafness, numbness, difficulty swallowing, incontinence, balance problems, seizures, tremors, and difficulty walking. The symptom of feeling unable to breathe, but where the lips are not turning blue, can indicate conversion disorder or sleep paralysis. Sleep paralysis and narcolepsy can be ruled out with sleep tests. These symptoms are attributed to conversion disorder when a medical explanation for the conditions cannot be found. Symptoms of conversion disorder usually occur suddenly. Conversion disorder is typically seen in people aged 10 to 35, and affects between 0.011% and 0.5% of the general population. Conversion disorder can present with motor or sensory symptoms including any of the following: Motor symptoms or deficits: Impaired coordination or balance Weakness/paralysis of a limb or the entire body (hysterical paralysis or motor conversion disorders) Impairment or loss of speech (hysterical aphonia) Difficulty swallowing (dysphagia) or a sensation of a lump in the throat Urinary retention Psychogenic non-epileptic seizures or convulsions Persistent dystonia Tremor, myoclonus or other movement disorders Gait problems (astasia-abasia) Loss of consciousness (fainting) Sensory symptoms or deficits: Impaired vision (hysterical blindness), double vision Impaired hearing (deafness) Loss or disturbance of touch or pain sensation Conversion symptoms typically do not conform to known anatomical pathways and physiological mechanisms. It has sometimes been stated that the presenting symptoms tend to reflect the patient's own understanding of anatomy and that the less medical