Canadian Concussion Centre

A concussion is a brain injury that is caused by a blow to the head such as an object striking the head or rapid movement of the head such as occurs in a car crash when you are struck from behind causing your head to move violently backwards and forwards. In the military, a concussion can also be from a blast.

Unfortunately, there is no lab test or imaging test that can diagnose a concussion, and the diagnosis of concussion is made by a medical doctor or other trained health care specialist such as a nurse practitioner.

There is often at least one clinical sign attributable to brain injury which may include:

• Loss of consciousness, although this is not common after a concussion
• Alteration of mental state such as slowed responsiveness, being dazed, inappropriate responses to questions, slowness to answer questions, agitation, inability to follow commands, brief disorientation to time, place or situation
• There may be brief amnesia or memory loss for a short time such as being unable to remember events shortly before or after the blow or movement of the head
• Other uncommon signs such as incoordination, seizure or posturing may occur for a short time after the concussion

Unfortunately, about 25% of people do not recover within a month and are then considered to have persisting concussion symptoms which can take several forms, and which can last moths or years or never go away.

There are about 70 symptoms that have been described after a concussion, and they can lost months or years and even be permanent, especially in people who have sustained multiple concussions. Here are some of them.

• Change in mental status – feeling confused, disorientated or dazed. Physical symptoms such as headaches, light and noise sensitivity, dizziness, vision changes, computer screen intolerance, and sleep and balance problems
• Cognitive symptoms: Mental fog, memory problems, difficulty concentrating
• Emotional symptoms: irritability, increased anxiety, low mood, emotional lability, PTSD

Usually, imaging with CT scans, or MRI is normal after a single concussion but may show some areas of brain damage after multiple concussions. Thus, imaging is normal after one concussion. For example a bleed in the brain would not occur after a concussion.

There are a few different theories for explaining what happens in the brain after a concussion in animals, but in fact the exact mechanisms are still a mystery. Animal and some human research have shown changes of different neurotransmitters in the brain. There does not seem to be a major change in blood flow or tearing of nerve fibers after a single concussion. In animal models there is evidence of inflammatory factors and other cells which can contribute to inflammation within the brain. We are studying many of these processes in our laboratories at UHN in brains donated to our research program into the condition called Chronic Traumatic Encephalopathy or CTE. This condition is characterized by chronic damage to the brain mainly in athletes whohad sustained multiple concussions. At this point the exact mechanismof CTE is unknown, although our own studies have shown important accumulations of abnormal proteins in the brain and considerable loss of normal nerve cells.

A concussed person should be at reduced activity for only the first 24 hours. This does not mean going into a dark room and doing nothing, but high intensity exercise should be avoided. Light activities such as usual activities of daily living include housework and low intensity walking are considered safe. Screen time should be minimal within the first 24 hours after injury. Then, low impact aerobic exercise should be gradually increased. Most people will improve within 2-4 weeks. It is important to seek professional advice to avoid prolonging symptoms. Every concussed person should be seen by aknowledgeable health care professional such as a medical doctor or nurse practitioner.

Seek health professional advice to assist with an individualised plan to return to school, sport or work. Avoid activities that have a high riskof concussion including contact sports without medical clearance.

Utilise seatbelts and suitable seat restraints for children.

If riding a bike or using an e-scooter use a helmet.

Review sport related techniques to avoid further injury. Never return to impact sports if symptoms persist. That is what lead to the death of Rowan Stringer, a 17 year old rugby player for an Ottawa high school who died of second impact syndrome which can cause terrible often untreatable swelling of the brain.

Ensure good footwear appropriate to the weather outside.

If you are elderly you are at special risk of concussion due to frequent issues with imbalance and vision, so do not forget yourcane or walker, or your glasses. Even putting on your underwear orgetting to the toilet on time are your big risks for concussion. If elderly, undertake exercises that improve neuromuscular balance such as Thai-chi or yoga

Regular aerobic exercise.

Be aware of your surroundings to avoid bumping your head.