Guyon's canal syndrome, also known as Guyon's tunnel syndrome, ulnar nerve entrapment of the wrist, and handlebar palsy, is a disorder affecting the ulnar nerve in the wrist. The most general cause of the condition is that the ulnar nerve, which extends the length of the arm to the wrist, experiences pressure as it is going through an area near the “pinky finger” side of the wrist — an area called Guyon's canal. The pressure can have many different causes, such as injury, arthritis, or even damage caused by activities associated with work or play that involve using the wrist.
Specifically, in order for someone to develop the condition, the ulnar nerve must have pressure applied to it or must be compressed. Generally, the compression occurs as the nerve reaches two tiny wrists bones that create a tunnel for the nerve, called Guyon’s canal. Many different factors can cause the compression or pressure.
One of the main causes of the syndrome is trauma to the wrist. The trauma is most frequently the result of a fractured or broken wrist bone. The broken bone can apply pressure to the nerve, leading to this syndrome. In addition, with certain kinds of wrist injuries, such as an injury from catching a ball, the wrist tissues might swell, putting undue pressure on the nerve. As a result, the person could experience the syndrome.
There are some secondary ailments that can also cause Guyon's canal syndrome. For example, a person with arthritis might experience this syndrome. As the joints and bones become inflamed, the inflammation can place pressure on the nerve. Also, a person with a blood clot might experience the symptoms associated with the syndrome; if the blood clot compresses the nerve, it can cause tingling and even pain on the “pinky” and “ring” fingers.
Among the most widespread causes of Guyon's canal syndrome are activities associated with a person’s work or play. Generally, any activity that involves continuous, repetitive wrist motions, such as twisting, gripping, and grabbing, can cause the syndrome. For example, a person who uses vibrating heavy machinery, such as a jackhammer, could experience the syndrome. In addition, a person who holds her wrists and hands unnaturally when maneuvering a computer mouse might develop the syndrome over time.
Bicycling also is one of most common causes, giving the syndrome its nickname, handlebar palsy. Specifically, the awkward placement of the wrists on the handlebars of many bikes, the hard grip that many cyclists use on their handlebars, and the vibration of the handlebar as the user pedals down the road or trail can lead to Guyon's canal syndrome. Other activities that can cause the syndrome include pushing a stroller and lifting dumbbell weights.