Typically, patients with concussions do not show organic changes on head CT scans; their primary clinical symptoms include temporary disturbances in consciousness after the injury and short-term memory loss. Some patients also experience varying degrees of headache, dizziness, nausea, vomiting, blindness, impaired memory, or lack of concentration, among other clinical symptoms. Generally, the essential tests include: first, a head CT scan; second, an electroencephalogram (EEG); third, cerebrospinal fluid examination.