Pronator teres syndrome

Pronator teres syndrome is a condition where one of the nerves of the forearm becomes compressed. In this respect, a specific forearm muscle plays an important role. Symptoms that occur with the pronator teres syndrome are pain, loss of sensation and decreased strength in the hand.

Description of the condition

The nerve in the forearm that becomes compressed in the pronator teres syndrome is called the median nerve. The pronator teres muscle plays an important role in this respect. This is the muscle in the forearm that turns the palm inwards.

When muscles tighten often and in a forceful manner, they become larger and thicker. This is usually a positive effect of training. But in case of pronator teres, it can also cause problems. This is because the median nerve runs through or just past the pronator teres muscle. When this muscle is overly developed, it can cause the nerve to become compressed.

As a result, symptoms start occurring in the service area of the nerve. People with the pronator teres syndrome, suffer from pain on the palm side of the forearm and loss of sensation in the thumb, index finger, middle finger and ring finger. There is also often question of a reduction in strength in the thumb. The symptoms usually subside when the arm has not been used (vigorously) for a while.

Cause and origin

Usually, the pronator teres syndrome is the result of overdevelopment of the pronator teres muscle in people who frequently, and forcefully, use it. Screw-driving or sports like golf and tennis are examples of this. The median nerve consequently becomes irritated. Connective tissue strands can also be obstructively present at this location or a direct blow to the forearm causes irritation to the nerve.

Signs & symptoms

Typical symptoms of the pronator teres syndrome are:

• Pain on the palm side of the forearm.
  
• Loss of sensation in forearm, thumb, index, middle and ring finger.
  
• Decrease in strength of forearm and thumb.
  
• The symptoms diminish at rest.
  
• Activities where the palm of the hand is turned downward, e.g. typing and screw-driving, aggravate the symptoms.

Diagnosis

A physician or physiotherapist will inquire after the symptoms and the manner of occurrence. This is followed by a physical examination. This involves looking at the strength of the muscles and the sensation in the forearm and fingers. It is also tested as to whether the symptoms increase when the pronator teres tightens. When tapped slightly below the elbow, it stimulates the nerve and it induces tingling.

If in doubt, an MRI scan or an electromyography (EMG) can be conducted. In case of an MRI, the physician examines the potential cause of the compression. An EMG measures the velocity at which a nerve transmits signals. With a compressed nerve, the conduction velocity decreases.

Treatment

Taking rest will reduce the symptoms. Potentially supported with a splint, medication and (hand) physiotherapy. The (hand) physiotherapist will try to bring the pronator teres to relaxation in order that the pressure on the nerve is reduced.

If, after a while (three to six months), there is still no or insufficient improvement then surgery may be an option. During this surgery, the surgeon frees the nerve, causing the symptoms to disappear. After the surgery, the arm can soon be used again. In this respect, it is important to follow the recommendations of the (hand) physiotherapist.

Exercises

You can check your symptoms using the online physiotherapy check or make an appointment with a physiotherapy practice in your area.

References
Dididze, M., Tafti, D. & Sherman A.l. (2021). Pronator Teres Syndrome. StatPearls Publishing LLC..