Post-concussion syndrome is a term used for a concussion that follows a longer than expected time for recovery. There is no consensus definition for this syndrome, making scientific study a challenge. A commonly used term to describe this condition is persistent post-concussive symptoms (PPCS). PPCS is likely caused by a combination of physiologic derangement, neurologic alterations, abnormalities of the vestibulo-ocular system, and psychological factors, among others. Evaluation can be done by examining the different systems contributing to symptoms, and focused treatments can be directed at abnormalities in certain areas. Complications of PPCS may include second impact syndrome, chronic traumatic encephalopathy (CTE), and depression/suicide, although these are also widely debated.