What Are the Most Common Symptoms of a Pinched Nerve in the Forearm?

Anterior interosseous nerve entrapment syndrome was reported by Kiloh and Nevin in 1952. Since then, related cases have been reported. The incidence of neuropathy in the distal forearm accounts for about 1%.

Basic Information

Visiting department

neurosurgery

Common locations

forearm

Common causes

Direct trauma

Common symptoms

Forearm and wrist pain

Causes of anterior interosseous nerve entrapment syndrome

The causes of anterior interosseous nerve entrapment symptoms can be divided into three categories:

1. Direct trauma.

2. Partial median nerve injury caused anterior interosseous nerve injury.

3. Neuropathy caused by entrapment or inflammation of anterior interosseous nerve.

Clinical manifestations of anterior interosseous nerve entrapment syndrome

The anterior interosseous nerve entrapment sign is a pure motor nerve palsy, which is manifested by weakened muscles of the flexor hallucis longus, index and middle finger deep flexors, and anterior rotator. In addition, the anterior interosseous nerve has a terminal sensation that dominates part of the wrist. Therefore, pain in the forearm and wrist is a common clinical manifestation of the disease.

Typical signs

Spontaneous pain often occurs in the palmar side of the proximal forearm, the pronator region, and the palmar side of the wrist. Symptoms worsen during exercise, especially when the forearm is active. Due to the pain, the movement of the limbs is restricted. Pain may resolve on its own within weeks or months. The typical clinical manifestations are weakened muscles of the flexor hallucis longus, deep finger flexors of the index and middle fingers, and anterior rotator muscle. The patient complains that it is often difficult to write or get small items, but there is no change in hand sensation.
The clinical signs were still weakened by the flexor hallucis longus, index and middle finger deep flexors, and anterior rotator muscles. The thumb and index pinch test is helpful for diagnosis.

2. Atypical anterior interosseous nerve entrapment syndrome

Anatomical and clinical characteristics Due to the frequent occurrence of anatomical variations, the clinical manifestations of anterior interosseous nerve compression often change to some extent.

(1) The middle finger deep flexor muscles can be innervated by the ulnar nerve (about 50%), so sometimes the clinical manifestations are only weakness of the thumb long flexor muscles and index finger deep flexor muscles.

(2) The Martin-Gurber anastomosis contract between the median nerve and the ulnar nerve accounts for 17%. The most common abnormal anastomotic branch is the anastomotic branch between the anterior interosseous nerve and the ulnar nerve. Compression of the anterior interosseous nerve can cause weakening of the intramuscular muscle strength.

(3) The deep finger flexors can be completely innervated by the anterior interosseous nerve. Therefore, the clinical manifestations of all the deep finger flexors are weakened.

(4) The anterior interosseous nerve can issue branches that dominate the superficial flexor of the fingers.

Anterior interosseous nerve entrapment syndrome

Feasible electromyography is helpful for diagnosis.

Diagnosis of anterior interosseous nerve entrapment syndrome

Electrophysiological examination is of important diagnostic value in identifying anterior interosseous nerve entrapment.

Differential diagnosis of anterior interosseous nerve entrapment syndrome

In the diagnosis of anterior interosseous nerve entrapment, the most common misdiagnosis is the rupture of the long flexor hallucis longus and deep flexor tendon of the thumb. Misdiagnosis of tendon tears as anterior interosseous nerve entrapment has also been reported. Therefore, the clinic should pay attention to identification. This disease should be distinguished from thoracic outlet syndrome, radicular cervical spondylosis, brachial plexus neuritis, and damage to the median nerve.

Treatment of anterior interosseous nerve entrapment syndrome

Choose different treatment methods based on the cause. Traumatic anterior interosseous nerve injury is generally observed for 3 to 4 months. If it cannot be recovered, surgery should be performed. For nerve damage caused by penetrating injuries, surgery should be performed immediately. For patients with anterior interosseous nerve injury caused by other compression factors, it can be treated according to specific conditions.

1. Non-surgical treatment can be used for rest, fixation, reduced forearm movement, and local closure. For those who do not respond to conservative treatment for 8-12 weeks, surgical treatment is feasible. The timing of conservative treatment is controversial in the literature and should be determined based on the cause and condition.

2. Surgical treatment is similar to that of pronation circular muscle syndrome. Struthers ligaments should be released during surgery, the biceps aponeurosis should be removed, the pronator round muscles should be released, and the compression factors existing in the anterior interosseous nerve should be released.