Radial nerve compression: anatomical perspective and clinical consequences

Results of Tendon Transfers in Radial Nerve Palsies: A New Evaluation Protocol

Radial nerve palsies present a challenging clinical scenario, often leading to substantial functional impairment. This study focuses on evaluating the outcomes of tendon transfer surgeries in patients with post-traumatic radial nerve injuries. The radial nerve, vital for upper limb movements, faces various etiologies, such as trauma, compression, or idiopathy. Patients with radial nerve palsy encounter difficulties in daily activities, emphasizing the need for effective management strategies. The research introduces a novel evaluation protocol, aiming to comprehensively assess tendon transfer outcomes. This protocol incorporates functional movements of wrist and finger joints, encompassing both objective and subjective parameters. The retrospective study includes eleven patients treated between 2010 and 2022, with a minimum follow-up of one year post-surgery. Tendon transfers demonstrated positive results. The evaluation protocol covers a wide range of parameters, including wrist and finger mobility, thumb function, grip strength, and patient satisfaction. The results indicate successful restoration of motor function, with an average grip strength of 70% compared to the healthy arm. The proposed evaluation protocol facilitates standardized and reproducible assessment, minimizing subjective errors in clinical evaluations. Despite the study's limitations, such as a relatively small sample size, the findings underscore the effectiveness of tendon transfers in treating radial nerve palsies. The introduced evaluation scheme provides a comprehensive and reproducible approach to assess outcomes, contributing to the global standardization of tendon transfer assessments in radial nerve injuries.

The brachioradialis longus: an unreported accessory form of the brachioradialis muscle

The brachioradialis muscle (BR) belongs to the lateral forearm muscle. Typically, the radial nerve innervates it. BR morphological variability, such as split muscular belly, split tendon, or accessory BR (ABR), has been described in the current literature. A 68-year-old female donated cadaver was routinely dissected for research and educational purposes. A variant muscle was identified extending at the right arm's lateral and forearm compartments. It originated from the humerus lateral surface between the deltoid and the triceps brachii lateral head, joined the second muscular head from the brachialis muscle, and inserted into the radius styloid process. According to its origin, course, and insertion, the variant muscle probably corresponded to the BR accessory form. However, in the current literature, the ABR morphology corresponds to an accessory muscle originating adjacent to the typical BR and inserted into the radial tuberosity. At the same time, it was defined as "brachioradialis brevis." In the current case, the variant muscle differed significantly from the current literature due to the origin, insertion, length, and relationship with the typical BR; therefore, the term "brachioradialis longus" seemed adequate to describe this variant muscle.

Exploring Symptom Responses to Upper Limb Neural Test Variations of the Radial Nerve in Patients With Lateral Epicondylalgia: An Observational Study

OBJECTIVE

Clinical practice guidelines recommend the radial nerve mechanosensitivity evaluation in patients with lateral epicondylalgia. Despite different positions and sequences having been described, no research analyzed how each variation triggers symptoms associated with lateral epicondylalgia. The aim of this study was to explore the effects of different positions and sequences in the upper limb neural tension test 2b (ULNT2b) in symptom responses in patients with lateral epicondylalgia.

METHODS

In this observational study, 66 patients underwent 4 test conditions: standard ULNT2b, ULNT2b proximal to distal, ULNT2B with resisted supination, and resisted supination isolated. Paresthesia sensations, symptom reproduction, pain intensity (measured using a visual analog scale), and distribution of painful symptoms data were collected.

RESULTS

Significant differences in paresthesia sensations were observed between groups, with significant differences between the standard ULNT2B and other ULNT variations or resisted supination maneuvers. Symptom reproduction also differed significantly across groups, with significant differences between the standard ULNT2B and other ULNT or resisted supination tests. The positive/negative test and percentage of distribution of painful symptoms scores varied significantly across 4 conditions in both lateral and frontal views. Although pain intensity scores during tests were comparable among the tests, distribution of painful symptoms differed significantly.

CONCLUSION

Variations in the ULNT2b test can affect symptom responses in patients with lateral epicondylalgia. The standard ULNT2b test appears more effective at reproducing symptoms, intensity of paresthesia, and distribution of painful symptoms compared to other ULNT variations and the resisted supination test.

IMPACT

ULNT2b sequences have been shown to elicit varying responses concerning paresthesia, replication of familiar symptoms, positive/negative test results, and distribution of painful symptoms. Clinicians should consider specific test variations during the patients' radial nerve mechanosensitivity assessment to identify aggravating factors reproducing recognizable symptoms. A control group of asymptomatic participants and the role of presence of other comorbidities, psychological factors, or the duration of symptoms were not considered in this study and might play an important role influencing the results of the tests.

A bilateral four-headed brachialis muscle with a variant innervation: a cadaveric report with possible clinical implications

PURPOSE

Anterior compartment muscles of the arm present high morphological variability, with possible clinical significance. The current cadaveric report aims to describe a bilateral four-headed brachialis muscle (BM) with aberrant innervation. Emphasis on the embryological background and possible clinical significance are also provided.

METHODS

Classical upper limb dissection was performed on an 84-year-old donated male cadaver. The cadaver was donated to the Anatomy Department of the National and Kapodistrian University of Athens.

RESULTS

On the left upper limb, the four-headed BM was supplied by the musculocutaneous and the median nerves after their interconnection. On the right upper limb, the four-headed BM received its innervation from the median nerve due to the musculocutaneous nerve absence. A bilateral muscular tunnel for the radial nerve passage was identified, between the BM accessory heads and the brachioradialis muscle.

CONCLUSION

BM has clinical significance, due to its proximity to important neurovascular structures and frequent surgeries at the humerus. Hence, knowledge of these variants should keep orthopedic surgeons alert when intervening in this area. Further dissection studies with a standardized protocol are needed to elucidate the prevalence of BM aberrations and concomitant variants.

[Rare nerve compression neuropathies]

UNCOMMON NERVE COMPRESSION SYNDROMES

In regard to the complex anatomical relationship of peripheral nerves and muscles, tendons, fasciae as well as their long course within those anatomical structures and additional close contact to bony structures, they are prone to suffer from local compression syndromes. Hence creating a vast majority of entrapment syndromes - well described in literature for almost every single nerve. The purpose of this article is to give an overview of symptoms, signs, diagnostic studies and treatment options, addressing especially the less known syndromes. Compression syndromes of the upper arm and shoulder region include the suprascapular nerve syndrome the compression of the axillary nerve within the spatium quadrilaterale and the compression of the long thoracic nerve at the chest wall. The upper extremity offers a variety of infrequent entrapment syndromes, as the pronator teres syndrome and anterior interosseus syndrome, both resulting from pressure to the median nerve in the forearm. Compression neuropathy in the course of the radial nerve in the distal upper extremity is also known as supinator syndrome. Guyon's canal syndrome is the ulnar side equivalent to the well-known carpal tunnel syndrome. In the case of a Cheiralgia paresthetica, a compression of a sensory branch of the superficial radial nerve can be seen. In the lower extremities, a variety of nerves especially in the groin and thigh area can be compressed as they pass through the narrow spaces between the abdominal muscles or underneath the inguinal ligament. Compression of the lateral femoral cutaneous nerve is the most common syndrome. Compression syndromes of the femoral and obturator nerves are most often iatrogenic. Pain around the knee, especially the lateral part and following orthopedic procedures of the knee, can arise from a compression or a lesion of a small infrapatellar branch of the saphenous nerve. Another probably underdiagnosed syndrome is piriformis syndrome, resulting from an entrapment of the sciatic nerve as it passes through certain muscular structures. In the distal lower extremity, the peroneal and tibial nerves can be compressed at multple sites, clinically known as peroneal nerve paralysis resulting from nerve compression around the fibular head, the anterior and posterior tarsal tunnel syndrome, and Morton's metatarsalgia.

Examining the Forearm Intersection through Palpation and Ultrasonography

BACKGROUND

Forearm intersection syndrome causes pain, swelling, and a rub at the dorsal distal forearm where the first extensor compartment muscles intersect with the second compartment tendons. Although primary care settings tend to treat mild cases, high-performance athletes may suffer from severe symptoms that require surgery. This proof-of-concept study aims to help detect the anatomical substrate of forearm intersection syndrome using palpation and ultrasonography when available.

METHODS

Five individuals were studied using independent palpation and ultrasonography to identify the first dorsal compartment muscles and the second dorsal compartment tendons. The distances between the dorsal (Lister's) tubercle of the radius and the ulnar and radial edges of the first dorsal compartment muscles were measured to determine the location and extent of the muscle-tendon intersection. The palpatory and ultrasonographic measurements were compared using descriptive statistics and the paired t-test.

RESULTS

The mean distances from the dorsal tubercle of the radius to the ulnar and radial borders of the first dorsal compartment muscles were 4.0 cm (SE 0.42) and 7.7 cm (SE 0.56), respectively, based on palpation. By ultrasonography, the corresponding distances were 3.5 cm (SD 1.05, SE 0.47) and 7.0 cm (SD 1.41, SE 0.63). Both methods showed a similar overlap length. However, ultrasonography revealed a shorter distance between the dorsal tubercle of the radius and the ulnar border of the first compartment than palpation (p = 0.0249).

CONCLUSIONS

Our findings indicate that a basic knowledge of anatomy should help health professionals diagnose forearm intersection syndrome through palpation and, if available, ultrasonography.

Pressure Pain Hypersensitivity and Ultrasound Changes in the Radial Nerve in Patients with Unilateral Lateral Epicondylalgia: A Case-Control Study

Some authors have proposed the potential role of the radial nerve in lateral epicondylalgia. The aims of this study were to investigate the presence of pressure pain hyperalgesia and nerve swelling (increased cross-sectional area) assessed with ultrasound imaging on the radial nerve in people with lateral epicondylalgia, and to investigate if an association exists between pressure pain sensitivity and cross-sectional area. A total of 37 patients with lateral epicondylalgia (43% women, age: 45.5 ± 9.5 years) and 37 age- and sex-matched pain-free controls were recruited for participation. Pressure pain thresholds (PPTs) were assessed bilaterally on the radial nerve at the spiral groove, the arcade of Frohse, and the anatomic snuffbox in a blinded design. Further, the cross-sectional area of the radial nerve at the spiral groove and antecubital fossa was also assessed. The results demonstrated lower PPTs on the radial nerve of the affected side in individuals with lateral epicondylalgia as compared with the unaffected side (p < 0.01) and with both sides in healthy controls (p < 0.001). Additionally, the cross-sectional area of the radial nerve on the affected side in patients was higher compared with the unaffected side (p < 0.01) and both sides in healthy controls (p < 0.001). The cross-sectional area of the radial nerve at the spiral groove was negatively associated with PPTs over the radial nerve at the spiral groove (r = -0.496, p = 0.002) and positively associated with function (r = 0.325, p = 0.045). Our findings revealed generalized pressure pain hyperalgesia and also nerve swelling of the radial nerve in people with lateral epicondylalgia, suggesting the presence of a widespread sensitization of nerve tissues in this population. The radial nerve could represent a potential peripheral drive to initial and maintain altered pain processing in lateral epicondylalgia.