What is the primary symptom of mild Traumatic Brain Injury (MTBI)?

The primary symptom of mild Traumatic Brain Injury (MTBI), often referred to as a concussion, is the loss of consciousness or disorientation. This can occur immediately following the injury and may manifest as confusion, difficulty remembering events, or a feeling of being dazed. These symptoms are crucial because they indicate an alteration in the brain's function due to trauma, which is central to the diagnosis of MTBI.

While severe cognitive decline, significant behavioral changes, and chronic headaches are symptoms linked to TBIs, they do not characterize mild cases as specifically as the loss of consciousness or disorientation does. Cognitive decline tends to be more associated with more severe forms of brain injury, and behavioral changes can develop over time or with more severe injuries. Chronic headaches may also occur but are more of a secondary symptom that can arise after the initial injury rather than a defining characteristic of mild traumatic brain injury. In essence, option B encapsulates the immediate and fundamental aspect of MTBI symptoms.