Isolated musculocutaneous nerve palsy during sleep

Axillary and musculocutaneous neuropathies

This chapter covers axillary and musculocutaneous neuropathies, with a focus on clinically relevant anatomy, electrodiagnostic approaches, etiologic considerations, and management principles. Disorders of the lateral antebrachial cutaneous nerve, a derivative of the musculocutaneous nerve, are also reviewed. We emphasize the importance of objective findings, including the physical examination and electrodiagnostic evaluation in confirming the isolated involvement of each nerve which, along with the clinical history, informs etiologic considerations. Axillary and musculocutaneous neuropathies are both rare in isolation and most frequently occur in the setting of trauma. Less commonly encountered etiologies include external compression or entrapment, neoplastic involvement, or immune-mediated disorders including neuralgic amyotrophy, postsurgical inflammatory neuropathy, multifocal motor neuropathy, vasculitic neuropathy, and multifocal chronic inflammatory demyelinating polyradiculoneuropathy.

Isolated Musculocutaneous Nerve Injury in a Professional Baseball Player: A Case Report

Introduction:

Musculocutaneous nerve lesion in a throwing athlete is a rare condition. We report the case of a professional baseball pitcher with an isolated musculocutaneous nerve lesion that occurred during a pitching motion.

Case Presentation:

The patient had radiating pain in the upper arm and weakness of elbow flexion. Physical examination revealed flaccid paralysis of the biceps brachii muscle and paresthesia in the right lateral forearm. Musculocutaneous nerve injury was suspected. Because some signs of recovery were observed within a few days, the patient received non-operative management. Nerve conduction studies at 2 weeks after the injury showed low-amplitude compound muscle action potential of the right biceps brachii muscle by stimulation of the musculocutaneous nerve. Needle electromyography showed markedly reduced motor unit potential recruitment in the biceps brachii muscle. He was diagnosed as having isolated musculocutaneous nerve injury. At 2 months after the injury, the muscle contraction and strength of the biceps brachii muscle improved. At 7 months after the injury, muscle weakness was fully recovered. His pitching ability returned to that of a competitive player.

Conclusion:

Because the neuroparalysis was incomplete and began to recover within a few days, we considered the pathology of this injury to be incomplete axonotmesis, which was successfully treated conservatively.

Communication between the musculocutaneous and median nerves in the arm: an anatomical study and clinical implications

Objective

To determine the frequency and features of communication between the musculocutaneous nerve (MCN) and median nerve (MN) in a sample of the Colombian population, and assess its clinical implication.

Methods

The arms of 53 cadaver specimens that had been subjected to necropsy at the National Institute of Forensic Medicine, in Bucaramanga, Colombia, were studied. The structures of the anterior compartment of the arm were dissected and characterized regarding the presence of communication between the MCN and MN.

Results

A communicating branch was found in 21/106 upper limbs (19.8%), occurring bilaterally in 10 (47.6%) and unilaterally in 11 (52.4%), without significant difference regarding the side of occurrence (p = 0.30). In 17% of the cases, there was MCN-MN communication in which the communicating branch was seen leaving the MCN after piercing the coracobrachialis muscle (Type I). In 2.8%, the connection was from the MN to the MCN (Type II). The length of the communicating branch was 57.8 ± 33.4 mm. The distances from the proximal and distal points of this branch to the coracoid process were 138 ± 39.4 mm and 188 ± 48.3 mm, respectively. The communicating branch was located mostly in the middle third of the arm.

Conclusions

The frequency of MCN-MN communication observed in the present study is in the middle of the range of what was reported in previous studies. MCN-MN connections need to be taken into account in diagnosing and managing peripheral nerve lesions of the upper limbs.

Isolated musculocutaneous neuropathy in an adolescent baseball pitcher

Injury of the musculocutaneous nerve very rarely occurs in the absence of concomitant injury to other components of the brachial plexus. Until now, the few cases of isolated musculocutaneous nerve palsies have been reported only in adults. We report a case of isolated musculocutaneous neuropathy in a uniquely talented adolescent baseball pitcher. The biomechanics underlying this adolescent's ability to throw with high velocity likely contributed to the musculocutaneous nerve injury in this case.