Pronator teres syndrome
Encyclopedia
Pronator teres syndrome is a compression neuropathy of the median nerve
at the elbow.
It is rare compared to compression at the wrist (carpal tunnel syndrome
) or isolated injury of the anterior interosseous branch of the median nerve (anterior interosseous syndrome
).
and passes between the two heads of pronator teres muscle into the forearm. It then runs between flexor digitorum superficialis and flexor digitorum profundus muscles and enters the hand through the carpal tunnel
.
It innervates most of the flexor muscles in the forearm and hand.
Its sensory component supplies the skin of the palm, thumb, index and middle finger as well as half the ring finger, and the bones of the wrist.
In the proximal forearm it gives rise to the anterior interosseous nerve
which innervates the flexor of the thumb (FPL), the flexor digitorum profundus of the index finger (FDP IF), and the pronator quadratus, and terminates in a sensory branch to the bones of the wrist, ie the carpal tunnel. Compression of the proximal median nerve results in weakness of these three muscles, and can cause aching pain in the wrist on the basis of the sensory nerve to the carpal bones.
("PQ").
of the forearm.
The flexor pollicis longus and FDP of the index finger are weak, leading to impairment of the pincer movement. This reflects involvement of the anterior interosseous nerve
.
Sensory changes may be found in the first three fingers as well as in the palm, indicating impairment of the median nerve proximal to the flexor retinaculum
.
Other causes are compression of the nerve from the fibrous arch of the flexor superficialis, or the thickening of the bicipital aponeurosis
.
or pure anterior interosseous syndrome
. Proper localisation is crucial to treatment options.
Conduction velocity of the median nerve in the proximal forearm may be slow but the distal latency and sensory nerve action potential at the wrist are normal.
Although MRI may show denervation atrophy of the affected muscles, its role in the evaluation of pronator teres syndrome is unclear.
Injection of corticosteroids into the pronator teres muscle produces may relief of symptoms, but a strong response to a steroid injection would be more consistent with carpal tunnel syndrome.
Massage therapy can also provide relief for individuals experiencing this condition.
Surgical decompression can provide benefit in selected cases.
Median nerve
The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....
at the elbow.
It is rare compared to compression at the wrist (carpal tunnel syndrome
Carpal tunnel syndrome
Carpal Tunnel Syndrome is an entrapment idiopathic median neuropathy, causing paresthesia, pain, and other symptoms in the distribution of the median nerve due to its compression at the wrist in the carpal tunnel. The pathophysiology is not completely understood but can be considered compression...
) or isolated injury of the anterior interosseous branch of the median nerve (anterior interosseous syndrome
Anterior interosseous syndrome
Anterior interosseous syndrome or Kiloh-Nevin syndrome I is a medical condition in which damage to the anterior interosseous nerve, a motor branch of the median nerve, causes pain in the forearm and a characteristic weakness of the pincer movement of the thumb and index finger.Most cases of...
).
Anatomy
The median nerve arises from the cubital fossaCubital fossa
The cubital fossa is the triangular area on the anterior view of the elbow of a human or other hominid animal. It is colloquially known as the "elbow pit".-Boundaries:...
and passes between the two heads of pronator teres muscle into the forearm. It then runs between flexor digitorum superficialis and flexor digitorum profundus muscles and enters the hand through the carpal tunnel
Carpal tunnel
In the human body, the carpal tunnel or carpal canal is the passageway on the palmar side of the wrist that connects the forearm to the middle compartment of the deep plane of the palm. The tunnel consists of bones and connective tissue...
.
It innervates most of the flexor muscles in the forearm and hand.
Its sensory component supplies the skin of the palm, thumb, index and middle finger as well as half the ring finger, and the bones of the wrist.
In the proximal forearm it gives rise to the anterior interosseous nerve
Anterior interosseous nerve
The anterior interosseous nerve is a branch of the median nerve that supplies the deep muscles on the front of the forearm, except the ulnar half of the flexor digitorum profundus....
which innervates the flexor of the thumb (FPL), the flexor digitorum profundus of the index finger (FDP IF), and the pronator quadratus, and terminates in a sensory branch to the bones of the wrist, ie the carpal tunnel. Compression of the proximal median nerve results in weakness of these three muscles, and can cause aching pain in the wrist on the basis of the sensory nerve to the carpal bones.
Symptoms
Compression of the median nerve in the region of the elbow or proximal part of the forearm can cause pain and/or numbness in the distribution of the distal median nerve, and weakness of the muscles innervated by the anterior interosseous nerve: the flexor pollicis longus ("FPL"), the flexor digitorum profundus of the index finger ("FDP IF"), and the pronator quadratusPronator quadratus
Pronator quadratus is a square shaped muscle on the distal forearm that acts to pronate the hand.As it is on the anterior side of the arm, it is innervated by a branch of the median nerve, the anterior interosseous nerve...
("PQ").
Clinical signs
The characteristic physical finding is tenderness over the proximal median nerve, which is aggravated by resisted pronationPronation
In anatomy, pronation is a rotational movement of the forearm at the radioulnar joint, or of the foot at the subtalar and talocalcaneonavicular joints. For the forearm, when standing in the anatomical position, pronation will move the palm of the hand from an anterior-facing position to a...
of the forearm.
The flexor pollicis longus and FDP of the index finger are weak, leading to impairment of the pincer movement. This reflects involvement of the anterior interosseous nerve
Anterior interosseous nerve
The anterior interosseous nerve is a branch of the median nerve that supplies the deep muscles on the front of the forearm, except the ulnar half of the flexor digitorum profundus....
.
Sensory changes may be found in the first three fingers as well as in the palm, indicating impairment of the median nerve proximal to the flexor retinaculum
Flexor retinaculum
Flexor retinaculum may be:* Flexor retinaculum of the hand, the retinaculum flexorum manus* Flexor retinaculum of the foot, the retinaculum musculorum flexorum pedis...
.
Causes
The most common cause is entrapment of the median nerve between the two heads of the pronator teres muscle.Other causes are compression of the nerve from the fibrous arch of the flexor superficialis, or the thickening of the bicipital aponeurosis
Bicipital aponeurosis
The bicipital aponeurosis is a broad aponeurosis of the biceps brachii which is located in the cubital fossa of the elbow and separates superficial from deep structures in much of the fossa....
.
Diagnosis
The clinical and electrophysiological features of pronator teres syndrome are quite different from patients with carpal tunnel syndromeCarpal tunnel syndrome
Carpal Tunnel Syndrome is an entrapment idiopathic median neuropathy, causing paresthesia, pain, and other symptoms in the distribution of the median nerve due to its compression at the wrist in the carpal tunnel. The pathophysiology is not completely understood but can be considered compression...
or pure anterior interosseous syndrome
Anterior interosseous syndrome
Anterior interosseous syndrome or Kiloh-Nevin syndrome I is a medical condition in which damage to the anterior interosseous nerve, a motor branch of the median nerve, causes pain in the forearm and a characteristic weakness of the pincer movement of the thumb and index finger.Most cases of...
. Proper localisation is crucial to treatment options.
Conduction velocity of the median nerve in the proximal forearm may be slow but the distal latency and sensory nerve action potential at the wrist are normal.
Although MRI may show denervation atrophy of the affected muscles, its role in the evaluation of pronator teres syndrome is unclear.
Treatment
Standard treatment of R.I.T.E. is recommended in young athletes prior to injections and/or surgical decompression. R.I.T.E. is an acronym for Rest Ice Therapy (physical) and Elevation. The therapeutic exercises may vary based on the Physical Therapist or Athletic Trainer's philosophy on mobility and motion.Injection of corticosteroids into the pronator teres muscle produces may relief of symptoms, but a strong response to a steroid injection would be more consistent with carpal tunnel syndrome.
Massage therapy can also provide relief for individuals experiencing this condition.
Surgical decompression can provide benefit in selected cases.