• concussion
• consensus statement

The consensus definition of concussion was only agreed in 20011 which means that concussion has just turned 18. It must, therefore, be viewed as an unruly teenager, rebellious and changing, but finally beginning to mature. Along the way, there has been a book, a film, extensive litigation and legislation, millions of words written in the media, thousands of peer-reviewed articles, more consensus meetings, more books and the threat of still more litigation. Hardly a week goes by without another story about concussion hitting the headlines and the centre of the concussion maelstrom is the USA.

In terms of global participation, volleyball leads the field with 998 million participants, followed by basketball (400 m), soccer (242 m), badminton (200 m) and tennis (60 m). Not the strongest line-up for sports involving concussion and in the USA, the list is only slightly …