The dual tendon palmaris longus variant causing dynamic median nerve compression in the forearm

Accessory Hand Muscles Over the Transverse Carpal Ligament: An Obstacle in Carpal Tunnel Surgery

BACKGROUND

Carpal tunnel syndrome (CTS) is an entrapment neuropathy caused by compression of the median nerve throughout the carpal tunnel. It is the most common entrapment neuropathy, with an estimated prevalence of 4%-7%. Surgical management is more effective in moderate to severe and severe CTS. CTS recurs in approximately 20% of patients, and up to 12% of these patients require reoperation. Knowledge of normal anatomy and variations would improve the success rate of the index surgery. Atypical causes of CTS were reported, including ganglion cysts, synovial hypertrophy, lipomas, bone fracture, bone fragments, tumor of soft tissues or bones, neurofibromas, neuromas, vascular malformations, and accessory muscles. Accessory muscles are commonly detected in upper limbs. However, their concomitant presentation with CTS has rarely been reported. We aimed to present different accessory muscles diagnosed during CTS surgery through a systematic review of the literature with our exemplary case.

METHODS

A systematic review/meta-analysis was performed concomitant with a case presentation.

RESULTS

Accessory muscles associated with CTS were as follows: palmaris longus, 28.6%; lumbrical muscles, 19.3%; palmaris profundus, 17.8%; flexor digitorum superficialis, 16.1%; transverse carpal muscle, 5%; flexor digitorum indicis, 4.2%; flexor superficialis indicis, 4.2%; flexor sublimis, 0.8%; accessory superficialis longus, 0.8%; flexor pollicis longus, 0.8%; abductor digiti minimi, 0.8%; abductor digiti quinti, 0.8%; and flexor digitorum superficialis brevis, 0.8%. Accessory muscles were mostly noticed during CTS surgery (88.2%).

CONCLUSIONS

Knowledge of possible variations within the carpal tunnel would improve the surgeon's capability during CTS surgery.

Etiology, Diagnosis, and Treatment of Dynamic Nerve Compression Syndromes of the Elbow Among High-Level Pitchers: A Review of 7 Cases

Background:

Dynamic compressive neuropathies around the elbow are a rare entity described by a relatively small body of literature, mostly consisting of single-case reports. No standardized diagnostic protocols have been described to date. To the authors’ knowledge, this study represents the largest case series of dynamic compressive neuropathies in the upper extremity.

Purpose:

To identify various etiologies of dynamic compressive neuropathies around the elbow, devise a systematic diagnostic protocol, and review treatment options.

Study Design:

Case series; Level of evidence, 4.

Methods:

A retrospective review was conducted of patients who presented to a single practice between 2013 and 2017 and were diagnosed with a dynamic compressive neuropathy around the elbow.

Results:

A total of 7 patients were identified, with a mean follow-up of 2 years. All patients were high-level pitchers. One patient was a minor league pitcher; 4 patients were National Collegiate Athletic Association athletes; and 2 patients were high school athletes. All patients underwent a systematic diagnostic workup. The diagnosis was established with dynamic nerve conduction testing. Three etiologies for dynamic nerve compression around the elbow were identified: 1 case of lateral antebrachial cutaneous nerve compression by the biceps tendon, 3 cases of ulnar nerve compression by an anconeus epitrochlearis muscle, and 3 cases of posterior interosseous nerve compression at the arcade of Frohse with hypertrophic extensor carpi radialis brevis and extensor digitorum communis muscles. Two patients were treated conservatively, while 5 patients required surgery. All patients were able to return to pitching.

Conclusion:

Dynamic compressive neuropathies around the elbow are rare entities that present unique diagnostic challenges to the treating clinician. In this cohort, all patients were young throwing athletes. Physical examination of the patient frequently lacks typical findings of chronic nerve entrapment syndromes. Dynamic nerve conduction studies establish the diagnosis, and treatment often requires surgical decompression to achieve complete resolution of symptoms.

Unusual Co-existence of Biaponeurotic Palmaris Longus and Accessory Abductor Digiti Minimi in Man

The present study describes a rarely reported co-existence of variant muscles in the right upper limb of a male cadaver of 57 years of age, observed during routine anatomical dissection. There was a presence of the biaponeurotic palmaris longus with a central muscle belly in the anterior forearm region which was closely related to the median nerve. In addition to this, an accessory abductor digiti minimi muscle was also reported in the corresponding hypothenar region, traversing the Guyon's canal, passing superficial to the ulnar vessels and nerves. Biaponeurotic palmaris longus and accessory abductor digiti minimi are important structural causes of the entrapment neuropathies of forearm and wrist. Diagnosis of these muscles as a cause of entrapment neuropathies requires the sound knowledge of variant muscles in the forearm and wrist region.