A concussion is a mild traumatic brain injury resulting from a blow or jolt to the head or body, causing the brain to move rapidly within the skull. This sudden movement disrupts the brain’s normal chemical balance and function, leading to temporary symptoms. Since a concussion is a functional injury, not a structural one, medical professionals evaluate the injury based on symptoms and performance rather than a simple scan. This clinical approach involves a thorough patient interview, a physical exam, and cognitive testing to determine the extent of the injury and guide recovery.
The Symptom Interview and Patient History
Evaluation begins with a detailed conversation with the patient or caregiver to establish the context of the injury. The doctor asks about the mechanism of injury, including how the event occurred and the direction of the force, to understand the energy transmitted to the brain. This initial history includes whether there was any loss of consciousness or a period of confusion immediately following the impact.
The doctor systematically reviews current symptoms, noting when they started and how they have changed. Patients are often asked about physical symptoms like headache, nausea, and dizziness, as well as sensory complaints like sensitivity to light or noise. Standardized tools, such as the Sport Concussion Assessment Tool (SCAT5), are frequently used to quantify the severity of common symptoms. This structured approach helps the clinician track changes over time and ensures that subtle symptoms like emotional lability or sleep disruption are not overlooked.
Physical and Neurological Examination
A physical and neurological exam assesses the brain’s ability to control various body functions. The doctor begins by checking vital signs and screening for signs of more severe trauma, such as tenderness in the cervical spine or indications of a skull fracture. The evaluation then proceeds to a focused assessment of the cranial nerves, which control functions like vision and facial movement.
The exam focuses on the ocular system, observing the smoothness of eye tracking, checking for involuntary eye movements (nystagmus), and testing pupillary response to light. Abnormalities in these checks can suggest disruption in the brain pathways controlling vision and eye alignment. Motor function is assessed by testing muscle strength, reflexes, and tone, looking for any focal weakness that might indicate a more serious underlying issue.
Balance and coordination are evaluated using specific tasks that challenge the patient’s equilibrium. These include the Romberg test, where the patient stands with feet together and eyes closed, and the tandem gait test, which requires walking heel-to-toe in a straight line. The doctor looks for unsteadiness, swaying, or an inability to complete the tasks, which can reveal vestibulo-ocular or cerebellar dysfunction caused by the concussion.
Assessing Cognitive Function and Memory
Cognitive assessment evaluates the brain’s higher-level abilities, which are particularly vulnerable to injury. The assessment typically begins by testing the patient’s orientation, asking them to state the current time, location, and the reason for their visit. The physician then moves to tasks that measure concentration and working memory, which may involve asking the patient to recite a series of numbers backward or list the months of the year in reverse order.
Memory is tested in two phases: immediate and delayed recall. For immediate recall, the patient may be given a short list of words to repeat back immediately, while delayed recall requires them to remember that same list of words after a five-to-ten-minute interval spent on other activities. Standardized tools, such as neurocognitive tests within the SCAT5 or computer-based programs like ImPACT, measure processing speed and reaction time. These objective tests are particularly useful for detecting subtle cognitive deficits that the patient may not consciously recognize or be able to articulate.
When Doctors Order Imaging Tests
Imaging tests, such as Computed Tomography (CT) scans or Magnetic Resonance Imaging (MRI), are generally not used to diagnose a concussion itself. Because a concussion is a functional disruption at the cellular level, it rarely causes structural changes visible on standard imaging. The primary purpose of ordering a CT or MRI is to rule out more dangerous, structural brain injuries.
A doctor will typically order a CT scan if there is concern for a skull fracture or bleeding inside the brain, such as an epidural or subdural hematoma. Criteria that prompt imaging include a worsening headache, repeated vomiting, seizures, or the presence of a focal neurological deficit like severe weakness on one side of the body. If symptoms persist for a prolonged period, an MRI may be used to look for more subtle or delayed changes in brain structure that might not be visible on a CT scan.