Traumatic brain injury (TBI) can result in impairments that are not perceivable on a clinical neurological level, causing a diagnostic limbo that underestimates this condition, as certain imaging techniques are unable to identify structural alterations. In order to identify dysfunctions that require a specific rehabilitation plan, it is particularly important that we consider post-concussion syndrome (PCS) an entity that requires diagnostic recognition through sensitive methods. New functional imaging strategies, specific neuropsychological tests, neurophysiological studies and, more recently, peripheral biological markers can contribute to its specific diagnosis. The objective of this study is to carry out a review of the literature and shed light on the concept and the different methods of diagnosing PCS, including an analysis of the potential utility of biological markers and the relevance of its clinical diagnosis to generate a comprehensive rehabilitation model.