Musculocutaneous Neuropathy: Case Report and Discussion

Abstract

The musculocutaneous nerve arises from the lateral cord of the brachial plexus and contains fibers from the C5, C6, and C7 spinal nerve roots. It innervates such muscles as the biceps brachii and brachialis as well as supply branches to the skin over the lateral cubital and forearm regions via the lateral antebrachial cutaneous nerve. Musculocutaneous neuropathy can arise from exercise, participating in sports, strenuous activity, cast placement, trauma, and surgery in addition to other less understood causes such as Parsonage Turner syndrome. We present the case of a 55-year-old female who complained of numbness, weakness, and pain throughout the arm starting 1 day following a surgical procedure. Electrodiagnostic testing revealed a musculocutaneous neuropathy with significant axonal injury. Symptoms of musculocutaneous neuropathy may be similar to cervical spinal nerve root impingement or brachial plexus lesions. Therefore, magnetic resonance imaging and electrodiagnostic studies may be useful in differentiating between these conditions. Once the diagnosis of musculocutaneous neuropathy has been made, treatments include relative rest, nonsteroidal anti-inflammatory drugs, splinting, physical therapy, and surgical decompression in cases that do not respond to conservative management.

High-resolution 3-Tesla magnetic resonance neurography of musculocutaneous neuropathy

“…1,[5][6][7]9,11 Most injuries to the musculocutaneous nerve involve the brachial plexus concomitantly, as was seen in our patients. 9 Rarely, patients present with isolated traumatic injury to the musculocutaneous nerve.…”

“…Surgical decompression is reserved for refractory cases and in cases of nerve transection. 1,8 Conclusion 3T MRN enables accurate visualization of musculocutaneous nerve injury and associated brachial plexopathy. It serves as a useful adjunct tool in the clinical decision-making process to determine the appropriateness of surgery.…”

“…5 High-resolution MRN and ultrasound imaging are play an important role in the diagnostic algorithm of peripheral neuropathies because they allow direct visualization of normal and abnormal nerves as well as the perineural compressive lesions. 1,3,9,12 Acute muscle denervation presents as uniform T2 hyperintensity on MRN within the first 24 to 48 hours, whereas these changes may not be depicted on EMG for 2 to 3 weeks. 5 Depiction of musculocutaneous nerve continuity is important because an earlier surgical intervention is associated with better prognosis.…”

Parsonage-Turner Syndrome

“…The upper trunk of the brachial plexus, the suprascapular nerve, the long thoracic nerve, and the axillary nerves are the most commonly involved [32,47,56,64,72,81]. Frequently reported, but less common, are the anterior interosseous, musculocutaneous, and spinal accessory nerves [5,15,32,42,50,57,64,83,84,93]. Least commonly involved are the ulnar, radial, and median nerves [61,74,76,78].…”

Isolated Traumatic Musculocutaneous Distal Branch Neuropathy

“…If symptoms persist beyond 6 weeks, injection of steroid and local anesthetic into the musculocutaneous tunnel may be performed in order to possibly alleviate the inflammatory component of the pain. If after 12 weeks nonoperative treatment for these neuropathies are unsuccessful, surgical 28 (18). Isolated musculocutaneous distal branch neuropathies can easily be overlooked in clinical practice.…”