A concussion is defined as a mild traumatic brain injury (mTBI) that temporarily affects normal brain functioning. Car accidents are one of the most common causes of this injury, second only to falls. Importantly, a concussion can occur even if the head does not strike any object inside the vehicle. Its effects are often unseen by the casual observer.
How Car Accidents Cause Concussions
The mechanism of a car accident concussion involves the sudden, violent movement of the head and body. When a vehicle abruptly stops, the body is thrown forward (acceleration) and then rapidly pulled back by the seatbelt (deceleration), often causing a whiplash motion. The brain, suspended in cerebrospinal fluid, continues to move after the skull stops.
This inertia causes the brain to slam against the inside of the skull, resulting in a coup-contrecoup injury. Beyond linear impact, the brain is also subjected to rotational forces, which cause a twisting or shearing of brain tissue. These forces stretch and damage brain cells and nerve fibers, temporarily disrupting normal cell communication.
The resulting cellular damage is functional rather than structural, meaning a concussion is not usually visible on standard scans. This explains why even minor collisions can lead to significant symptoms.
Recognizing Signs of a Concussion
Concussion symptoms fall into several categories and can be immediate or delayed. Physical symptoms are often the most apparent and include:
- Headache, nausea, or vomiting.
- Poor balance and fatigue.
- Sensitivities such as blurred vision, ringing in the ears (tinnitus), or intolerance to light or noise.
Cognitive symptoms affect how the brain processes information, often presenting as confusion, difficulty concentrating, or feeling mentally “foggy.” Memory issues, such as an inability to recall events immediately before or after the accident (post-traumatic amnesia), are common. Emotional or sleep-related changes also occur, including increased irritability, anxiety, sadness, or disturbances in sleep patterns.
Symptoms can be delayed, sometimes taking hours or days to fully manifest. Anyone experiencing a worsening headache, repeated vomiting, seizures, slurred speech, or increasing disorientation should seek immediate emergency medical attention. Loss of consciousness is not required for a concussion to occur, and it is present in less than 10% of cases.
The Medical Evaluation Process
A medical evaluation begins with a thorough history and a detailed neurological examination. The professional assesses various functions, including mental status, balance, coordination, and reflexes. Standardized tools, such as the Sport Concussion Assessment Tool (SCAT5), are often used to evaluate symptoms and cognitive function.
These tests assess factors like immediate memory, concentration, and orientation, providing a baseline measure of function. Balance testing is a key component, as postural instability is frequently reported after a concussion. The diagnosis is a clinical judgment based on the patient’s reported symptoms, the mechanism of injury, and the neurological exam findings.
Imaging tests like a CT scan or MRI are generally not used to diagnose a concussion, as the injury is primarily functional. Neuroimaging is performed only when there are “red flag” symptoms or concerns about a more severe structural injury, such as bleeding or a skull fracture. If symptoms persist beyond a week, an MRI may be used for a more detailed examination of subtle findings.
Guidelines for Concussion Recovery
Initial treatment involves a brief period of relative rest, both physical and cognitive. Current guidelines recommend starting light activities and gentle movement, like walking, within the first 24 to 48 hours, rather than strict isolation. This early, active rehabilitation helps reduce the risk of symptoms persisting.
Activities must be kept below a “symptom threshold,” meaning they should not significantly worsen the person’s symptoms. Once symptoms are minimal or resolved, a gradual, stepwise “Return to Activity” protocol can begin. This progression involves slowly reintroducing mental tasks, such as office duties, followed by light aerobic exercise.
Each step of the protocol lasts at least 24 hours, and the patient must tolerate the activity without a significant return of symptoms before advancing. Concussion symptoms typically resolve within two to four weeks. When symptoms like headaches, dizziness, or memory issues persist beyond this timeline, the condition is referred to as Post-Concussion Syndrome (PCS).