Concussion, more appropriately called mild traumatic brain injury, refers to any trauma-induced alteration in brain function. An obvious corollary of this is that patients must have head trauma causing some neurologic symptoms (though these may be very brief) in order to be diagnosed as having had a concussion. Common symptoms are confusion and amnesia, imbalance, dizziness, and headache. The injury may or may not involve loss of consciousness, but when present, the period of alteration of mental status is generally brief (less than 30 minutes).

Initial assessment of the patient with concussion should be focused on determining whether urgent neuroimaging is required. When indicated, computed tomography (CT) is the preferred modality to rule out intracranial hemorrhage, which might require close monitoring and/or urgent neurosurgical intervention. Clinical decision tools, such as the Canadian CT Head Rule, are useful in this assessment. Basic information on the mechanism of injury and specific high-risk patient features should be obtained first, as this information may lead to a rapid decision to proceed directly to imaging. For example, imaging is recommended for all patients over age 60 years with concussion, regardless of specific neurologic symptoms or findings.

If no high-risk patient features are present, then a thorough assessment of neurologic symptoms and function should be performed to guide the decision on whether imaging is necessary. Milder neurologic symptoms, such as headache, dizziness, balance difficulties, and confusion, are common after head impacts but do not necessarily warrant head imaging unless one of these more concerning features is present.

If brain CT is abnormal and demonstrates acute hemorrhage, hospital admission with close neurologic monitoring should be undertaken given the risk of hemorrhage expansion, particularly in the first 24 hours after injury.

The vast majority of individuals with concussion will have normal head CT scans and do not require hospital admission. Providing anticipatory guidance to these patients has been associated with improved outcomes. Patients should receive a description of their injury and its severity, education regarding common symptoms and those that warrant emergency room reevaluation, details of the recovery process and return to activity, and contact information for appropriate community resources. Symptom management beyond over-the-counter analgesics and antiemetics is generally not required, as the vast majority of patients will experience a slow recovery over the next 1–4 weeks without pharmacologic intervention. In the past, patients had been counseled to undertake complete cognitive and physical rest until their symptoms resolve. However, more recent evidence demonstrates that this approach is associated with increased symptoms and prolonged recovery. Therefore, a graduated return to normal daily activities is recommended after a brief period of rest (24–72 hours).