Pronator Syndrome Research Articles

A-0386 8.5 Surgical treatment of pronator syndrome

A-0386 8.5 Surgical treatment of pronator syndrome

Peripheral Neuropathies of the Median, Radial, and Ulnar Nerves: MR Imaging Features

The median, radial, and ulnar nerves of the upper limbs may be affected by various peripheral neuropathies, each of which may be categorized according to its cause, as either an entrapment or a nonentrapment neuropathy. Entrapment neuropathies, also referred to as nerve compression syndromes, include the supracondylar process syndrome, pronator syndrome, anterior interosseous nerve syndrome, carpal tunnel syndrome, posterior interosseous nerve syndrome, cubital tunnel syndrome, and Guyon canal syndrome. Nonentrapment neuropathies include traumatic nerve injuries, infectious and inflammatory conditions, polyneuropathies, and mass lesions at anatomic locations where entrapment syndromes typically do not occur. Although clinical examination and electrophysiologic testing are the cornerstone of the diagnostic work-up, in certain cases magnetic resonance (MR) imaging may provide key information about the exact anatomic location of a lesion or may help narrow the differential diagnosis. In patients with a diagnosis of peripheral neuropathy, MR imaging may help establish the cause of the condition and provide information crucial for conservative management or surgical planning. In addition, knowledge of the normal anatomy and of the possible causes, typical clinical findings, and MR imaging features of peripheral neuropathies that affect the median, radial, and ulnar nerves allows greater confidence in the diagnosis.

Role of magnetic resonance imaging in entrapment and compressive neuropathy—what, where, and how to see the peripheral nerves on the musculoskeletal magnetic resonance image: part 2. Upper extremity

The diagnosis of nerve entrapment and compressive neuropathy has been traditionally based on the clinical and electrodiagnostic examinations. As a result of improvements in the magnetic resonance (MR) imaging modality, it plays not only a fundamental role in the detection of space-occupying lesions, but also a compensatory role in clinically and electrodiagnostically inconclusive cases. Although ultrasound has undergone further development in the past decades and shows high resolution capabilities, it has inherent limitations due to its operator dependency. We review the course of normal peripheral nerves, as well as various clinical demonstrations and pathological features of compressed and entrapped nerves in the upper extremities on MR imaging, according to the nerves involved. The common sites of nerve entrapment of the upper extremity are as follows: the brachial plexus of the thoracic outlet; axillary nerve of the quadrilateral space; radial nerve of the radial tunnel; ulnar nerve of the cubital tunnel and Guyon's canal; median nerve of the pronator syndrome, anterior interosseous nerve syndrome, and carpal tunnel syndrome. Although MR imaging can depict the peripheral nerves in the extremities effectively, radiologists should be familiar with nerve pathways, common sites of nerve compression, and common space-occupying lesions resulting in nerve compression in MR imaging.

Pronator Syndrome and Other Nerve Compressions That Mimic Carpal Tunnel Syndrome

The purpose of this clinical commentary is to provide a comprehensive review of compressive neuropathies that may mimic carpal tunnel syndrome, provide the clinician with information to differentially diagnose these median nerve compression sites, and provide an evidence-based opinion regarding conservative intervention techniques for the various compression syndromes. While rare in comparison to carpal tunnel syndrome, pronator syndrome and anterior interosseous nerve syndrome are proximal median nerve compressions that may be suspected if a patient with carpal tunnel syndrome fails to respond to conservative or surgical intervention. Differential diagnosis is based largely on the symptoms, patterns of paresthesia, and specific patterns of muscle weakness. Due to the relative rarity of pronator syndrome and anterior interosseous nerve syndrome, few controlled studies exist to determine the most effective treatment techniques. Based on sound anatomical and biomechanical considerations, anecdotal experience, and available research, however, treatment strategies for pronator syndrome and anterior interosseous nerve syndrome compression neuropathies can be divided into 4 major categories: (1) rest/immobilization, (2) modalities, (3) nerve gliding, and (4) nonconservative treatment.

Pronator Syndrome and Other Nerve Compressions That Mimic Carpal Tunnel Syndrome

Pronator Syndrome and Other Nerve Compressions That Mimic Carpal Tunnel Syndrome

Compression neuropathies of the median nerve

Specific compression syndromes of the median nerve are known in the proximal forearm and at the wrist. Carpal tunnel syndrome is the best known and most common, but pronator teres syndrome and anterior interosseous nerve syndrome also are clinically significant. In this discussion, we review the history, relevant anatomy, diagnosis, and treatment modalities for these compression syndromes.

Pronator Syndrome: A Retrospective Study of Median Nerve Entrapment at the Elbow in Female Machine Milkers

Pronator syndrome (median nerve entrapment at the elbow) is a rare condition, but it is more common among women than men. A long-term retrospective follow-up study evaluating the outcome of surgical release of the median nerve for female machine milkers has never been carried out before, nor has a long-term study of non-treated female milkers with pronator syndrome. In the present study, two groups of machine milkers (surgical and non-surgical) were compared. The clinical examination focused on two parameters: focal tenderness and individual muscle strength. The results showed that the surgical group had no focal tenderness on palpation over the median nerve at the elbow and no selective weakness in the muscles examined, as compared to what was found before surgery. In the non-surgical group, focal tenderness was found in 12 out of 14, and 10 out of 14 showed the same weakness as in an earlier examination. While this study has limitations in sample size, surgical release of the median nerve at the elbow level, in cases of pronator syndrome, appears to provide an immediate as well as long-term return to normal strength of FPL and FDP II, along with a significant improvement in subjective status. In the non-surgical group, spontaneous improvement of the strength of FPL and FDP II was found in only four out of the 14 cases.

PRONATOR SYNDROME

Although pronator syndrome is often misdiagnosed and does not occur as frequently as carpal tunnel syndrome, its clinical features are well described, and the diagnosis should be made if the clinical features are understood and reasonable suspicion exists. The differentiating features between carpal tunnel syndrome and pronator syndrome should be understood, and evaluation for one site of compressive neuropathy of the median nerve always should include the other potential sites. When the correct diagnosis is made, pronator syndrome can be successfully treated nonoperatively or surgically, if necessary.

A CASE OF “NORMAL” RADICULOPATHY

We followed up a woman, aged 58, presenting with difficulty in fine finger movements, moderate‐to‐severe strength deficit at right thumb opposition, and ipsilateral thenar and hypothenar atrophy, but no pain or loss of sensibility. A series of electromyograms performed between November 1996 and June 1997 pointed to motor polyneuropathy with conduction block. Lumbar puncture was negative and routine blood chemistry showed erythrosedimentation rate to oscillate between normal and increased values. Antinuclear and antiendomysium autoantibodies were present, but anti‐GM1 autoantibodies were negative. Cervical CT scan showed right C5‐C6 and C6‐C7 foraminal stenosis supported by joint hypertrophy.The patient was subjected to intravenous immunoglobulin infusion and gluten‐free diet with no improvement. Subsequent clinical follow up and electromyograms showed no conduction block or multiple motor involvement. A suspected diagnosis of round pronator syndrome was ruled out by neurophysiological data, clinical examination, and history. X‐ray with oblique projections and magnetic resonance imaging confirmed CT data. Currently, the same localised deficits persist, with no extension to other districts; a mild improvement was seen after kinesiotherapy.This case was complicated by initial misdiagnosis of neuropathy of immunological origin, due to overestimation of nonspecific or isolated laboratory data. In this case, simply focusing on X‐ray data and greater attention to clinical examination and reported symptoms allowed a correct diagnosis of “simple” cervical radiculopathy.

鏡視下手根管解放術後再発例の経験

Three patients (4 hands) had recurrence of symptomes after receiving endoscopic carpal tunnel release.Physical examination at our hospital indicated that all patients had ipsilateral pronator syndrome. Operations for carpal tunnel and pronator syndrome were performed at the same time. In the findings of the carpal tunnel, sever adhesion around the median nerve and insufficiently incised transverse carpal ligament were seen in all hands but one hand, which had received a second open method operation prior to visiting our complicated pronator syndrome one discussed.Pronator syndrome shows similar symptons to the clinical features of the carpal tunnel syndrome, and It is therefore easily misdiagnosed as carpal tunnel syndrome. It is stressed that pronator syndrrome must be considered in the differential diagnosis of carpal tunnel syndrome.

再発を繰り返した回内筋症候群の一例

This is a report of a case of the pronator syndrome which relapsed three times and was operated on four times.Case: A 70 year old female with a complaint of paresthesia in the median nerve region and muscle weakness in the right index finger. A positive Tinel's sign at both proximal forearm and wrist were elicited and a nerve conduction test revealed the slowing of conduction velocity in the forearm and prolongation of distal motor latency across the carpal tunnel. The patient was diagnosed as having both the pronator syndrome and the carpal tunnel syndrome. A release operation for the median nerve was performed June 1996, and symptoms remitted, but, recurred two months later, the nerve having been compressed by the exostosis of the radius. This tumor was resected February 1997 and again symptoms remitted, recurred four months later. July 1997, the operation to release the nerve compressed by the pronator teres muscle was performed and symptons disappeared, but recurred 21 months later, the nerve having been compressed by the osteochondroma of the ulna which was resected April 1999. To date, the patient has been free from symptoms for more than 7 months.

異常虫様筋が関与したと思われる手根管症候群の１例

A rare case of carpal tunnel syndrome caused by an anomalous lumbrical muscle, associated with ipsilateral pronator syndrome, is reported.An 18-year-old male was operated on for left carpal tunnel syndrome and pronator syndrome.Upon division of the transverse carpal ligament, very slight changes due to compression could be seen on the surface of the median nerve and an abnormal muscle was seen on the medial side of the median nerve. The muscle arose from the radial aspect of the flexor profundus tendon to the index finger and the distal margin of the origin was 2cm proximal to the transverse crase of the wrist but portions more proximal of the origin and insertion of the muscle could not be identified. On traction of this muscle, the metacarpo-phalangeal joint of index finger was flexed. In the proximal forearm, the median nerve was compressed by abnormal accessory insertion of the brachialis muscle, bicipital aponeurosis and hypertrophied humeral head of the pronator teres muscle. We assume that the carpal tunnel syndrome was caused not only by the abnormal lumbrical muscle but also by the compression in the proximal forearm (multiple crush).

Operative treatment of pronator syndrome

Decompression of the median nerve in the area of the pronator teres. Symptoms persisting after proper conservative care. Presence of motor deficits. Poor health. Incision over the tender point. Exposure and division of the lacertus fibrosus. Identification of the median nerve and search for evidence of compression. Look for anatomical variations. Follow nerve distally and search for a bridge of the flexor digitorum superficialis. Report of 21 patients (7 men and 14 women, average age 57.7 years, 23 to 82 years). Three patients had bilateral surgery. Seventeen times another entrapment neuropathy was present. Average follow-up period 26 months (3 to 148 months). Except for 2 patients who experienced a recurrence, all patients were relieved of their symptoms. Disappearance of dysaesthesia was seen in 1 patient on the day of surgery. Dysaesthesia improved or disappeared in 11 patients within 1 week and in 6 between 1 and 2 weeks. In 3 patients the outcome was not recorded. A postoperative haematoma was observed twice. No other complications were noted.

Upper extremity nerve involvement in Swedish female machine milkers.

Entrapment of the median nerve in the proximal forearm, the so-called pronator syndrome, is considered a rather rare condition but it is four times more common in women than in men. In this study, 23 of 30 female machine milkers with symptoms in the forearm and hand were clinically diagnosed as having the pronator syndrome. The diagnosis of median nerve involvement was based on the clinical history and on physical examination by a hand surgeon. All 23 milkers complained of aching in the volar part of the forearm and had a sensation of numbness, tingling, and decreased muscle strength in their hands, mostly in the hands which usually were statically loaded with heavy equipment. Objectively, all had an experience of tenderness over the pronator teres muscle. Furthermore, they showed reduced muscle strength, especially in the following muscles: pronator teres (PT), flexor carpi radialis (FCR), flexor pollicis longus (FPL), and flexor digitorum profundus II (FDP II). To validate the manual muscle testing, Mannerfeldt's intrinsicmeter was used to quantify the clinically observed weakness. Eight of the 23 milkers with pronator syndrome were surgically released from neuropathy and were almost symptom-free at follow-up after six months. One patient had a slight sensation of numbness and had to be given surgical carpal tunnel release later on. The external exposure of the arm during the application of the milking cluster probably causes muscle and fascial tensions that induce compression of the nerve. Further studies are needed to establish the level of the internal exposure.

Pronator syndrome: poor outcome of surgical release

Pronator syndrome: poor outcome of surgical release

Gantzer's muscle: An anatomical study of the accessory head of the flexor pollicis longus muscle

The relationship of Gantzer's muscle (the accessory head of flexor pollicis longus; FPL) to the median nerve and its anterior interosseous branch is debated. In an anatomical study of 25 limbs, the incidence, origin, insertion, nerve supply and relations of Gantzer's muscle have been documented. The muscle was found in 13 of the 25 (52%) limbs and was supplied by the anterior interosseous nerve. It arose from the medial humeral epicondyle in 85% and had a dual origin from the epicondyle and coronoid process in the rest. Its insertion was to the ulnar part of FPL and its tendon. Gantzer's muscle always lay posterior to both the median and anterior interosseous nerves. Anatomical variations in which Gantzer's muscle may contribute to median nerve compression in pronator syndrome are discussed.

Intraepineurial Constriction of Nerve Fascicles in Pronator Syndrome and Anterior Interosseous Nerve Syndrome

In PS or AINS, if obvious epineurial compression deformity of the median nerve or the AIN is not found at known sites of compression, IeCNF should be considered. IeCNF may occur in one or more nerve fascicles of the median nerve at one of multiple levels in the distal upper arm and proximal forearm. Decompression of the nerve fascicles is achieved by epineurotomy, microsurgical interfascicular dissection, and removal of the constricting outer layer of the perineurium above and below the elbow. Resection of the constricted segments of the nerve fascicles is not necessary. Intraepineurial exploration of the nerve trunk also may be considered if, after surgical decompression of PS and AINS, expected recovery has not occurred and there is no evidence of axonal degeneration.

Median nerve entrapment at the elbow in athletes

Median nerve compression at the elbow in athletes presents a challenge to the practicing orthopaedic surgeon/sports medicine clinician. The surgeon should first carefully evaluate the athlete to determine where the source of compression is localized. If surgery is indicated, complete decompression must include release of the median nerve at (1) the ligament of Struthers, (2) lacertus fibrous, (3) between the two heads of the pronator teres, and (4) arcade of the flexor digitorum superficialis, which are all implicated in pronator syndrome. The anterior interosseous nerve may require additional decompression into the deep volar compartment of the forearm for relief of anterior interosseous syndrome symptoms.

The anterior interosseous nerve latency in the diagnosis of severe carpal tunnel syndrome with unobtainable median nerve distal conduction

This study assesses the role of the anterior interosseous nerve latency (AINL) in the differential diagnosis of severe carpal tunnel syndrome (CTS) with unobtainable median nerve distal conduction (UMNDC). The nonrandomized control trial took place at a referral center. Patients and other participants were categorized as follows: 25 healthy subjects; 25 patients with CTS; 11 patients with polyneuropathy; 5 men with mononeuritis and UMNDC; 2 men with pronator teres syndrome (PTS); 5 men with acute CTS and UMNDC; and 11 women with neglected CTS and UMNDC. The AINL was determined in all participants using surface and needle recordings. Electromyographic examination of the pronator quadratus (in all patients) and the median nerve innervated forearm muscles (in the last three groups of patients) was performed. Furthermore, surgical exploration of the median nerve at the wrist was performed in the 16 patients with CTS and UMNDC. The AINL obtained from patients was compared with the AINL of the control subjects. Also, the electrophysiological and surgical findings were compared. The AINL of control subjects ranged from 2.6 to 4.4ms (X̄ = 3.15 ± 0.5) and from 3.1 to 5.2ms (X̄ = 3.95 ± 0.5) on surface and needle recordings, respectively. The AINL in patients with CTS did not exceed the longest latency obtained from control subjects. The AINL was prolonged in patients with polyneuropathy and PTS, and unobtainable in patients with mononeuritis. Surgical exploration in the 16 patients confirmed the presence of severe median nerve compression at the wrist. Surface recording of the AINL could differentiate severe CTS with UMNDC, or with slow median motor nerve conduction velocity at the forearm, from median neuropathy or proximal compression.

Median nerve compression within the humeral head of pronator teres

We describe a case of the pronator syndrome caused by compression of the median nerve by a fibrous band as the nerve passed through the humeral head of origin of pronator teres. This rare anatomical arrangement resulted in displacement of the median nerve to the anterior aspect of the medial humeral epicondyle and, as far as we are aware, has not previously been described as a site of compression neuropathy.