Premier League approves trial of permanent concussion substitutes

The Premier League has voted to introduce permanent concussion substitutes.

Clubs approved the trial during a meeting on Wednesday, although there is no start date yet.

A concussion is a mild brain injury normally caused by a bump or blow to the head.

Teams will be able to make up to two permanent substitutions in the event of head injuries, as well as their three regular substitutions during a match.

Doctors already test players for possible concussion when they suffer a suspected head injury

The Premier League is the first competition in the world to agree to the trial.

The International Football Association Board (Ifab), the body that makes and approves the laws of football, approved the trials of concussion substitutes at a meeting in December.

Fifa, which governs world football, has already announced it will trial substitutions for actual or suspected concussion at the Club World Cup in Qatar later this month.

What is concussion?

Concussion is a type of head injury that occurs when the brain knocks against the inside of the skull

Concussion is a type of head injury. It happens when someone gets a significant bang on the head - so much that the brain is shaken and knocks against the inside of the skull.

This causes the nerves and structures in the brain to be altered, which means messages aren't sent around the brain in the right way.

If a person is concussed, there are ways it can be spotted. For example:

• Visual signs: Looking dazed or confused, not moving, being slow or unsteady, behaving differently

• Inability to answer questions such as what the time is or what they were doing last week

• Physical symptoms: Headache, being sick, being sensitive to light or noise

It can be serious and it might take someone several days to recover if they have a very bad bang to the head.

Some people think that in order to get concussion, you have to be knocked unconscious - but that isn't true.