Depersonalization can affect all aspects of human mental activity, resulting in a variety of symptoms or combinations of symptoms that may constitute an independent disorder, or may be part of other disorders such as depression or anxiety, or may co-exist with other disorders as a disorder (co-morbidity). In the latter case, the symptoms of depersonalization often persist after treatment for other disorders, because depersonalization is usually more difficult to treat than other disorders, and depersonalization is mostly insensitive to medication and electroconvulsive therapy (MECT). In another case, the symptoms of depersonalization are apparent only after the depression and anxiety have improved, is this related to the use or withdrawal of antidepressants? Or are the perceptions brought about by the illness too conflicting with the original trivial view? It is not known. The sensory system is the most commonly affected part of the depersonalization process. Typical symptoms include feelings of unfamiliarity, unreality, ambiguity, and emptiness, and can lead to many other symptoms that are not easily recognized and are often misdiagnosed or missed. For example, when depersonalization affects external senses (visual, auditory, etc.), it can lead to dizziness, unstable walking, and fear of falling, because natural and smooth walking requires the navigation of external sensory system; when depersonalization affects internal senses such as proprioception, it can lead to floating feeling of walking, such as stepping on cotton, not knowing how far or how deep it is, because the balance and coordination of the body and the sense of stability and accuracy require muscles, tendons, ligaments, and joints. The deep structures such as muscles, tendons, ligaments and joints need correct and timely feedback of position information. I asked her what it was like to step on cotton and feel the bottom. She said that each foot was false, so she deliberately stepped on it harder with each foot. The girl above had a mild attack of stepping on cotton 2 years ago, which lasted for about 2 to 3 months and then improved on its own. This gives us an important insight that many patients with depersonalization often have one or even a few mild episodes that do not heal themselves before the symptoms become apparent. Once depersonalization is formed, it is difficult to treat. The current diagnosis of this girl is not really difficult, as she still has a very obvious sense of unreality in this episode, but it was still missed. Her mother is a doctor and has seen several hospitals, both for her depression and anxiety, and for her cotton-stepping sensation, but mainly from an organic point of view, and all the tests were done, but the cause could not be found. The root cause of the missed diagnosis was that the doctors were unfamiliar with depersonalization as a disorder, and none of them questioned her about her inauthentic feelings. The most typical symptom of depersonalization is inauthenticity, and once she was asked about her inauthenticity, the clue to the diagnosis came. When the spinal cord is compressed by diseases such as cervical spondylosis, or when the posterior cord of the spinal cord is damaged by diseases such as spinal consumption, the transmission of proprioceptive information is affected, which can also lead to unstable walking, floating and unsteady, and a feeling of walking like stepping on cotton (sensory ataxia). If the sensation of stepping on cotton is due to organic causes, it is less likely to be misdiagnosed or missed, and can be detected by physical examination and CT and MRI.