Second impact syndrome: why you must not play on after concussion

The UK Concussion Guidelines for Non-Elite (Grassroots) Sport, published by the Sport and Recreation Alliance, define concussion as a traumatic brain injury resulting in a disturbance of brain function that affects the way a person thinks, feels and remembers things. Loss of consciousness occurs in less than 10% of concussions and is not required for the diagnosis.

The same guidance explains the concern behind second impact syndrome: playing on with symptoms of concussion can make them worse and significantly delay recovery, and if another head injury occurs, can result in more severe injury and, in rare cases, death. It is used mainly as the reason behind the rule of removing anyone with suspected concussion from the at-risk activity straight away. Detailed incidence figures are not given in the sources used for this page, and it should be understood as a rare event, not a common one.

The guidance notes that concussions can happen at any age, but that children and adolescents may be more susceptible to concussion, take longer to recover (and returning to education too early may worsen symptoms and prolong recovery) and are more susceptible to rare and dangerous neurological complications, including death caused by a second impact before recovering from a previous concussion.

A history of previous concussion increases the risk of a further concussion, which may take longer to recover from, and a recent concussion also increases the risk of other sport-related injuries such as musculoskeletal injuries. Concussion can follow a direct blow to the head, but can also occur when knocks to other parts of the body cause rapid movement of the head, as in whiplash-type injuries.

The grassroots guidance lists signs and symptoms that may suggest concussion, and says that any one of them after a head injury should lead to immediate removal from play. It also says the first symptoms typically appear immediately or within minutes but may be delayed over the first 24 to 48 hours, and that additional symptoms such as mood changes, sleep disorders and problems with concentration can appear over the following days.

• Headache, dizziness or feeling off-balance.

• Mental clouding, confusion or feeling slowed down; feeling in a fog or having difficulty concentrating.

• Disorientation, not aware of surroundings such as the score or opponent.

• Visual problems, nausea, fatigue, or a feeling of pressure in the head.

• Sensitivity to light or sound, being more emotional, or simply not feeling right.

• Concerns expressed by a parent, official or spectator about the player.

The grassroots guidance lists red flags that require urgent medical assessment, onsite or in A&E, using emergency ambulance transfer if necessary: any loss of consciousness, deteriorating consciousness, amnesia for events before or after the injury, increasing confusion or irritability, unusual behaviour change, any new neurological deficit (such as difficulty understanding, speaking, reading or writing, loss of balance, weakness, double vision or a seizure), severe or increasing headache, repeated vomiting, severe neck pain, any suspicion of a skull fracture, previous brain surgery or a bleeding disorder, current blood-thinning therapy and current drug or alcohol intoxication.

The NHS head injury page says to call 999 if someone has hit their head and has been knocked out and has not woken up, cannot stay awake, has a fit, has problems with vision or hearing, has clear fluid coming from the ears or nose, has new numbness or weakness, has problems with walking, balance, understanding, speaking or writing, or their behaviour has changed. It advises NHS 111 if they are being sick, feel dizzy, take blood-thinning medicine, were drinking alcohol or taking drugs at the time, or you are worried about any other symptom.

The guidance is unambiguous: anyone with a suspected concussion should be immediately removed from play, must not return to the activity that day, and should be assessed by an appropriate healthcare professional or via NHS 111 within 24 hours. If a neck injury is suspected, the person should be moved only by suitably trained professionals. They should not be left alone for the first 24 hours, should avoid alcohol and driving in that period, and should rest and sleep as needed in the first 24 to 48 hours, with limited screen use.

The NHS adds that most head injuries are not serious but concussion can last a few weeks, that symptoms may last up to 2 weeks, and that an adult should stay with the person for at least the first 24 hours. It advises not going back to work or school until feeling better and not driving until fully recovered.

Return to education or work takes priority over return to sport. After a period of relative rest of 24 to 48 hours, the guidance describes a staged return to normal life and then sport at a rate that does not worsen symptoms more than mildly. Progression through the stages depends on the activity not more than mildly aggravating symptoms. Full pre-injury mental activity should be achieved before unrestricted sport is considered.

Individuals with concussion should only return to sport that risks head injury after following the graduated programme and being evaluated by a healthcare professional. The guidance says there should be no return to competition before 21 days from injury, and that children and adolescents may take longer to recover than adults. If symptoms last more than 28 days, see a GP. Ask the GP if you are unsure whether it is safe to drive or return to work, school or sport, as the NHS also advises.

For most people concussion is assessed by a GP, NHS 111, an urgent treatment centre or an emergency department, depending on severity. The grassroots guidance is written for settings where healthcare professionals are typically not available onsite, which is why NHS 111 within 24 hours is its default route.

Elite and professional sport may have access to healthcare professionals experienced in sports concussion who run an individualised multidisciplinary management plan, according to the guidance. Some people choose a private sports physician or neurologist for a second opinion, and it helps to take any NHS notes with you.