When it comes to pain and numbness/tingling involving the median nerve there are two possibilities for the condition involved. The more well known carpal tunnel but theres also Pronator Teres Syndrome which can account for very similar but distinctly different symptoms.
What is it?
Pronator Teres Syndrome describes the combination of signs and symptoms that results from the compression of the median nerve by the pronator teres muscles, which is located near the elbow. It is the second most common cause of median nerve compression with features similar to carpal tunnel syndrome. Carpal-tunnel-like symptoms but involve the palm suggest pronator teres involvement.
Pronator teres syndrome is responsible for 9-12% of all cases of median nerve entrapment. The median nerve attaches to the flexor muscles in the forearm and hand supplying sensation to the anterior (front) forearm, palm, and first 3 fingers.
Pronator syndrome occurs when the median nerve is entrapped by the pronator teres muscle. It is associated with prolonged or repetitive forearm pronation and finger flexion, for example gripping with the palm down.
Carpenters, mechanics, assembly line workers, tennis players, rowers, and weight lifters are predisposed to this problem. The condition is often associated with excessively developed forearm muscles and is more common in the dominant arm. Like other neuropathies, patients with diabetes, alcoholism, or hypothyroidism are predisposed to this condition.
Clinical Presentation
Pronator syndrome often presents as an aching discomfort in the palm side of the forearm with associated paresthesia into the first three fingers. This condition may be exacerbated by repetitive activity.
There are ways to differentiate carpal tunnel and pronator teres syndrome which include nocturnal symptoms and range of motion. Nocturnal exacerbations are common in carpal tunnel syndrome but absent in pronator syndrome. Both conditions have symptoms with wrist flexion, but the symptoms of pronator syndrome are often increased with resisted or repetitive forearm pronation and supination.
Clinical evaluation of pronator syndrome demonstrates tenderness to palpation over the pronator teres muscle. Pronator syndrome may be associated with weakness of the muscles that are innervated by the median nerve.
Failure to identify and treat additional sites of compression will likely result in ongoing symptoms.
Diagnosis
Standard imaging testing such as ultrasound and MRI are not helpful in making a diagnosis of pronator syndrome. X-ray images are usually limited to bony pathology rather than neuropathy. Diagnostic ultrasound demonstrates abnormalities in approximately 57% of the confirmed pronator teres syndrome cases.
Management
An effective conservative management strategy includes rest, modalities, and nerve gliding exercises. One of the most important aspects of treatment is avoidance of repetitive and forceful gripping. Activity modification may be necessary. A discussion of work ergonomics and specifically avoiding repetitive tasks is essential.
Once the symptoms are no longer acute, stretching and myofascial release of hypertonic pronator teres and wrist flexor are warranted. Stretching should be performed prior to nerve mobilization.
Nerve mobilizations should not proceed past the point of symptoms provocation or exacerbation.
Studies show that 50% of pronator syndrome patients reported resolution of symptoms within four months of initiating care. Surgical decompression of the median nerve is considered only when nonoperative management fails.
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