It is called “olfactory disorder” and is classified as hyposmia or loss of smell according to the degree. There are four main causes: ① Nasal obstruction, airflow does not reach the olfactory mucosa. ② Various diseases that damage the olfactory nerve. ③Some SARS patients are damaged by SARS virus and have loss of sense of smell. ④Some drugs such as betamethasone inferior turbinate closure may also cause loss of smell. Olfactory impairment can cause a lot of disadvantages and even danger to patients’ life, such as eating without the normal sweet sensation, not being able to perceive spoiled food before eating and eating it by mistake, or even not being able to perceive gas leakage causing gas poisoning or burning vegetables after forgetting to burn them to make a fire. Therefore, it is recommended to go to the otorhinolaryngology department of the hospital for a comprehensive examination and evaluation of nasal and intracranial disorders and treatment of the primary disease when olfactory impairment occurs. When neurogenic olfactory disorders remain after the primary disease has been treated, treatment is more difficult. The Department of Pain Medicine and the Department of Otolaryngology have teamed up to treat the cause of neurogenic olfactory disorder with cervical sympathetic nerve modulation technique and achieved good results. The cervical sympathetic nerve usually has 3 to 4 ganglia, namely the superior cervical ganglion, the middle and middle cervical ganglia and the inferior cervical ganglion. Its distribution is extremely wide, not only to the blood vessels of the head, neck and upper limbs, sweat glands and erector spinae, but also to the pharynx and heart, and branches to the pupil opening muscle, oral glands, thyroid gland and glands of the nasal mucosa. The olfactory region of the nose (olfactory cells) is located in the mucosa of the upper turbinate and the upper part of the nasal septum. Studies have shown that blocking the cervical sympathetic nerve can diastole the blood vessels, speed up the blood flow, increase the local oxygen content and facilitate the repair of tissues, thus also restoring the function of olfactory cells within the nasal mucosa. For a better quality of life, one cannot ignore subhealth, and only early treatment can lead to satisfactory results. Just like having a stone weighing down a sapling, only by moving the stone as early as possible can the sapling thrive and not wither and die. Therefore, if you can’t smell the smell, you should go to the hospital as early as possible to stop the problem!