Anatomy of the medial antebrachial cutaneous nerve and its significance in ulnar nerve surgery: An anatomical study

Isolated medial antebrachial cutaneous nerve injury after blunt trauma: a case report

BACKGROUND

The medial antebrachial cutaneous nerve is a branch of the brachial plexus that contains C8-T1 segments. Injury of this nerve by various mechanisms has been reported in the literature; however, currently, there is no reported case of medial antebrachial cutaneous nerve injury in the setting of acute blunt trauma.

CASE PRESENTATION

This case report presents the case of a 34-year-old Persian female with dysesthesia and pain in the medial side of the forearm immediately following a blunt trauma by mechanism of elbow external rotation. On electrodiagnostic evaluation, the medial antebrachial cutaneous nerve sensory nerve action potential of the symptomatic side had a significant amplitude drop (more than 50%), compared with the other side. On follow-up electrodiagnosis, after several sessions of physical therapy, the medial antebrachial cutaneous nerve sensory nerve action potential still had a significant amplitude difference.

CONCLUSION

Blunt trauma can be one of the causes of medial antebrachial cutaneous nerve involvement. An electrodiagnostic study can be helpful in the diagnosis of this nerve injury after blunt trauma.

Anatomy of the posterior branch of the medial antebrachial cutaneous nerve: A cadaveric study

PURPOSE

The posterior branch of the medial antebrachial cutaneous nerve (MACN) is at risk to be damaged during cubital tunnel surgery. The purpose of this study was to identify the location of the posterior branch of the MACN (PBMACN) in relation to surgical landmarks pertinent in cubital tunnel surgery.

METHODS

We performed an anatomical study on 20 limbs from 13 fresh cadavers. The nerve was dissected from 10cm proximal to 10cm distal of the medial epicondyle. We measured the distance between the nerve and the medial epicondyle, and also the distance separating the PBMACN from the ulnar nerve passage between the two heads of the flexor carpi ulnaris. Measurements were performed with the elbow at 45° and 90° of flexion, as well as in full pronation and supination.

RESULTS

After its emergence from the main trunk of the MACN, the posterior branch ran anteriorly to the medial epicondyle, taking an oblique direction toward the ulnar shaft. The PBMACN was in average 2.53cm under the medial epicondyle when the elbow was flexed at 45°, and 2.96cm when the elbow was flexed at 90°. Average distance between the PBMACN and the penetrating point of the ulnar nerve within the flexor carpi ulnaris was 1.54cm when the elbow was flexed at 45°, and 1.62cm when the elbow was flexed at 90°. Pronation and supination positions of the forearm did not significantly modify our measurements.

CONCLUSIONS

Understanding the position of MACN posterior branch during ulnar nerve release surgery at the elbow may help in preventing iatrogenic injury. According to our measurements, incision and superficial dissection anterior to the medial epicondyle or distal to the ulnar nerve penetrating point between the two heads of the flexor carpi ulnaris should be avoided or done with an elbow flexed at 90°.

Brachial Plexus Injuries in Sport Medicine: Clinical Evaluation, Diagnostic Approaches, Treatment Options, and Rehabilitative Interventions

The brachial plexus represents a complex anatomical structure in the upper limb. This "network" of peripheral nerves permits the rearrangement of motor efferent fibers, coming from different spinal nerves, in several terminal branches directed to upper limb muscles. Moreover, afferent information coming from different cutaneous regions in upper limb are sorted in different spinal nerves through the brachial plexus. Severe brachial plexus injuries are a rare clinical condition in the general population and in sport medicine, but with dramatic consequences on the motor and sensory functions of the upper limb. In some sports, like martial arts, milder injuries of the brachial plexus can occur, with transient symptoms and with a full recovery. Clinical evaluation represents the cornerstone in the assessment of the athletes with brachial plexus injuries. Electrodiagnostic studies and imaging techniques, like magnetic resonance and high-frequency ultrasound, could be useful to localize the lesion and to define an appropriate treatment and a functional prognosis. Several conservative and surgical techniques could be applied, and multidisciplinary rehabilitative programs could be performed to guide the athlete toward the recovery of the highest functional level, according to the type of injury.

Ultrasound Imaging of Disorders of Small Nerves of the Extremities: Less Recognized Locations

Ultrasound is a well-proven imaging modality for showing peripheral nerve disorders and guiding perineural injections. The aim of this review is to focus on small peripheral nerve abnormalities, which are usually not recognized by sonologists. In fact, most of these small nerves have a tiny diameter (<2 mm), and their anatomy is less familiar. We describe the most common causes of small peripheral nerve disorders, providing an accurate description of their anatomic locations and relationships with adjacent structures; we also focus on technical hints that may help in their evaluation.

Modified contralateral C7 nerve transfer: the possibility of permitting ulnar nerve recovery is confirmed by 10 cases of autopsy

Contralateral C7 nerve transfer surgery is one of the most important surgical techniques for treating total brachial plexus nerve injury. In the traditional contralateral C7 nerve transfer surgery, the whole ulnar nerve on the paralyzed side is harvested for transfer, which completely sacrifices its potential of recovery. In the present, novel study, we report on the anatomical feasibility of a modified contralateral C7 nerve transfer surgery. Ten fresh cadavers (4 males and 6 females) provided by the Department of Anatomy, Histology, and Embryology at the Medical College of Fudan University, China were used in modified contralateral C7 nerve transfer surgery. In this surgical model, only the dorsal and superficial branches of the ulnar nerve and the medial antebrachial cutaneous nerve on the paralyzed side (left) were harvested for grafting the contralateral (right) C7 nerve and the recipient nerves. Both the median nerve and deep branch of the ulnar nerve on the paralyzed (left) side were recipient nerves. To verify the feasibility of this surgery, the distances between each pair of coaptating nerve ends were measured by a vernier caliper. The results validated that starting point of the deep branch of ulnar nerve and the starting point of the medial antebrachial cutaneous nerve at the elbow were close to each other and could be readily anastomosed. We investigated whether the fiber number of donor and recipient nerves matched one another. The axons were counted in sections of nerve segments distal and proximal to the coaptation sites after silver impregnation. Averaged axon number of the ulnar nerve at the upper arm level was approximately equal to the sum of the median nerve and proximal end of medial antebrachial cutaneous nerve (left: 0.94:1; right: 0.93:1). In conclusion, the contralateral C7 nerve could be transferred to the median nerve but also to the deep branch of the ulnar nerve via grafts of the ulnar nerve without deep branch and the medial antebrachial cutaneous nerve. The advantage over traditional surgery was that the recovery potential of the deep branch of ulnar nerve was preserved. The study was approved by the Ethics Committee of Fudan University (approval number: 2015-064) in July, 2015.

Ultrasound Imaging for the Cutaneous Nerves of the Extremities and Relevant Entrapment Syndromes: From Anatomy to Clinical Implications

Cutaneous nerve entrapment plays an important role in neuropathic pain syndrome. Due to the advancement of ultrasound technology, the cutaneous nerves can be visualized by high-resolution ultrasound. As the cutaneous nerves course superficially in the subcutaneous layer, they are vulnerable to entrapment or collateral damage in traumatic insults. Scanning of the cutaneous nerves is challenging due to fewer anatomic landmarks for referencing. Therefore, the aim of the present article is to summarize the anatomy of the limb cutaneous nerves, to elaborate the scanning techniques, and also to discuss the clinical implications of pertinent entrapment syndromes of the medial brachial cutaneous nerve, intercostobrachial cutaneous nerve, medial antebrachial cutaneous nerve, lateral antebrachial cutaneous nerve, posterior antebrachial cutaneous nerve, superficial branch of the radial nerve, dorsal cutaneous branch of the ulnar nerve, palmar cutaneous branch of the median nerve, anterior femoral cutaneous nerve, posterior femoral cutaneous nerve, lateral femoral cutaneous nerve, sural nerve, and saphenous nerve.

Imaging appearance following surgical decompression of the ulnar nerve

Ulnar neuropathy at the elbow is the second most common entrapment neuropathy of the upper extremity. Yet, there is a paucity of literature focusing on the imaging appearance following surgical decompression of the ulnar nerve at the elbow. Diagnostic imaging studies obtained after surgical decompression at The University of Michigan were reviewed and imaging findings were documented. We aim to describe the various techniques of ulnar nerve decompression and corresponding post-operative appearance on imaging. Potential complications following decompression will also be described with imaging and clinical correlation of recalcitrant ulnar neuropathy. It is important for the radiologist who performs MRI or ultrasound of the elbow to be aware of the various ulnar nerve decompression procedures. This knowledge will facilitate rapid and accurate diagnosis of normal and abnormal appearance of the ulnar nerve in this context.