If you are any kind of American Football fan, you've probably heard the term stinger. Simply put, a stinger is an injury to a nerve in the neck. It's a common injury among players involved in contact sports. Getting hit on the head from one side is usually enough to do it. A cervical nerve (coming from the spinal cord to the arm in the neck) gets stretched or pinched.

Burning pain down the arm after getting hit is the main symptom. There may be additional symptoms of arm weakness and numbness. The symptoms are usually transient (temporary) and go away within 24-hours. But repeated stingers over time can eventually lead to a chronic stinger syndrome. With a chronic stinger, symptoms of neck and shoulder pain with numbness, tingling, and weakness don't go away.

Having a means of predicting who might develop a chronic stinger syndrome would be helpful. With this information, athletes could be advised on the risks associated with repeated stingers. This is important because many athletes who suffer from one stinger will have more than one. And given the fact that up to 65 per cent of all American Football players get at least one stinger, the number of players affected is pretty high.

Imaging studies are used to help predict who might develop a chronic stinger syndrome. In the past, a ratio called the Torg ratio was used. This is a way of using X-rays to assess the diameter of the opening for the spinal cord and spinal nerve(s). Narrowing of the spinal canal (where the spinal cord is located) causes a condition called stenosis. It's the stenosis that puts pressure on the cord or nerves causing symptoms.

It turns out that the Torg ratio is highly sensitive (it accurately tells who has the problem). But it has a poor positive predictive value, which means it doesn't predict who (with stenosis) will develop actual neurologic symptoms. The Torg ratio doesn't account for the effect of the surrounding soft tissues. In using statistical measurements like this, positive predictive values are more clinically meaningful than sensitivity.

So, surgeons have turned to the mean subaxial cervical space available for the cord (MSCSAC) index to predict chronic stinger syndrome. This is a measurement made using MRIs that looks at the diameter of the spinal cord in comparison to the diameter of the spinal canal. It gives a much more accurate picture of what's going on and who might develop a chronic stinger syndrome.

Most players who do experience persistent symptoms from a chronic stinger recover. With conservative care, they are able to return to 100 per cent participation in their sport. Anyone suffering an acute stinger should be advised to rest and avoid contact sports (anything that could cause traction, compression, or direct blow to the head/neck).

Some players use a special collar called a cowboy collar to protect the neck. This is worn during play and practice. Some players use a special collar called a Cowboy Collar to protect the neck. This is worn during play and practice. It is a cervical collar (fits around the neck) underneath the shoulder pads. The Cowboy Collar fills the gap between the helmet and the shoulder pads. When worn with regular shoulder pads, the Cowboy Collar helps absorb shock.

Special exercises to help stabilize the head and neck are encouraged. Players should be told that multiple stingers and chronic stinger syndrome are linked with degenerative changes in the spine that can cause problems much later in life.

Reference: Jared Greenberg, MD, et al. Predicting Chronic Stinger Syndrome Using the Mean Subaxial Space Available for the Cord Index. In Sports Health. May-June 2011. Vol. 3. No. 3. Pp. 264-267.