Concussions are usually categorized into several levels based on the severity of their clinical symptoms. Generally, the higher the level, the more pronounced the symptoms in patients. They can generally be divided into five levels. Patients with a level one concussion may experience mild consciousness disturbances, but these are short-lived and generally do not leave noticeable residual effects. Patients with a level two concussion might experience slight headaches and dizziness, accompanied by vertigo. Patients with a level three concussion show evident retrograde amnesia. Patients with a level four concussion experience mild disturbances in consciousness, manifesting as states of drowsiness, stupor, or coma. Patients with a level five concussion present with clear clinical symptoms, characterized by recurrent headaches, dizziness, nausea, and vomiting.