Radial Tunnel Syndrome

Posterior interosseous nerve lesion due to lipoma. Review of the literature and rare case presentation

BACKGROUND

Posterior interosseous nerve lesion is a rare mononeuropathy of the upper limb. Atraumatic posterior interosseous nerve lesions are commonly caused by lipomas of the forearm, manifesting as slow-progressing wrist and finger drop.

PATIENTS AND METHODS

In this review and case report study, we present a systematic review of the literature for patients presenting with posterior interosseous palsy due to lipomas and a rare case of patient with acute posterior interosseous nerve lesion caused by a lipoma. Our primary interest was in the timing of clinical presentation. For the review process, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines.

RESULTS

After reviewing the literature, we identified thirty patients with posterior interosseous nerve lesions caused by lipomas. In 28 patients, the symptoms presented progressively, ranging from 1 month to a maximum of 240 months. We found only one case of a patient with acute presentation and another patient with acute worsening of chronic weakness due to trauma.

CONCLUSIONS

Atraumatic posterior interosseous nerve lesions are frequently secondary to forearm lipomas. In the majority of cases, the symptoms will develope progressively. However, in this study, we also report a rare case of a patient presenting with acute posterior interosseous nerve lesion due to a lipoma.

Magnetic Resonance Imaging Findings of Extensor Carpi Radialis Brevis Origin and Synovial Fold in Lateral Epicondylitis

Purpose

Magnetic resonance imaging (MRI) is the most widely used imaging to diagnose lateral epicondylitis (LE). However, the importance of MRI findings in LE remains unclear. This study aimed to classify the signal intensity changes of the extensor carpi radialis brevis origin and the shape and length of the synovial fold using MRI and compare them with clinical symptoms. We hypothesized that MRI findings in LE are not associated with clinical symptoms.

Methods

Two hundred and forty-three patients (261 elbows, mean age: 51.2 ± 8.5 years, mean duration of LE: 18.2 ± 11.3 months) who were evaluated using pretreatment MRI were included. The signal change of the extensor carpi radialis brevis origin was classified using coronal T2-weighted (T2) imaging and coronal fat-suppressed proton density T2 imaging, and the shape and length of the synovial folds were evaluated using coronal and sagittal T2 imaging. Furthermore, MRI findings were compared with clinical symptoms at the first visit.

Results

The number of elbows with high signal intensity on fat-suppressed proton density T2 was 252 of 261 (96.5%), and those on T2 were 207 of 261 (79.3%). Synovial folds were observed in 231 of 261 (88.5%) of the elbows, and synovial folds having a dull shape were observed in 95 of 261 (36.4%) elbows. The length of the synovial fold was >1/3 of the radial head in 87 of 261 (33.3%) of the elbows. There was no statistically significant correlation between the MRI findings and clinical symptoms.

Conclusions

A high rate of high signal intensity changes of the extensor carpi radialis brevis origin was observed, and fat-suppressed proton density T2 could detect finer signal changes than T2. Furthermore, synovial folds were found in many cases of LE. However, there was no association between MRI findings and clinical symptoms at first visit.

Type of study/level of evidence

Prognostic IV.

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.

Posterior Interosseous Neuropathy Related to a Loose Distal Biceps Cortical Button: A Case Series

Posterior interosseous nerve (PIN) injury is an uncommon yet debilitating complication following distal bicep tendon repair. There are case reports of acute intraoperative PIN injury related to retractor placement, drill trajectory, and nerve incarceration. We report three cases of delayed PIN neuropathy in the setting of a loose cortical button. All patients had resolution of their pain with removal of the cortical button and decompression of the radial tunnel. The purpose of this case series is to: 1) highlight the possibility of a loose cortical bicep button as the cause of proximal forearm pain and PIN neuropathy in the early or late postoperative timeframe; and 2) emphasize the importance of proper surgical technique and use of intraoperative fluoroscopy to assure the cortical button is well-fixed and flush with the radial shaft. .

Role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of peripheral nerves in the upper extremity

Upper extremity entrapment neuropathies are common conditions in which peripheral nerves are prone to injury at specific anatomical locations, particularly superficial regions or within fibro-osseous tunnels, resulting in pain and potential disability. Although neuropathy is primarily diagnosed clinically by physical examination and electrophysiology, imaging evaluation with ultrasound and magnetic resonance neurography are valuable complementary non-invasive and accurate tools for evaluation and can help define the site and cause of nerve dysfunction which ultimately leads to precise and timely treatment. Ultrasound, which has higher spatial resolution, can quickly and comfortably characterize the peripheral nerves in real time and can evaluate for denervation related muscle atrophy. Magnetic resonance imaging on the other hand provides excellent contrast resolution between the nerves and adjacent tissues, also between pathologic and normal segments of peripheral nerves. It can also assess the degree of muscle denervation and atrophy. As a prerequisite for nerve imaging, radiologists and sonographers should have a thorough knowledge of anatomy of the peripheral nerves and their superficial and deep branches, including variant anatomy, and the motor and sensory territories innervated by each nerve. The purpose of this illustrative article is to review the common neuropathy and nerve entrapment syndromes in the upper extremities focusing on ultrasound and magnetic resonance neurography imaging.

Radial Tunnel Syndrome: Review and Best Evidence

Radial tunnel syndrome (RTS) is caused by compression of the posterior interosseous nerve and consists of a constellation of symptoms that have previously been characterized as aspects of other disease processes, as opposed to a distinct diagnosis. First described in the mid-20th century as "radial pronator syndrome," knowledge regarding the anatomy and presentation of RTS has advanced markedly over the past several decades. However, there remains notable controversy and ongoing research regarding diagnostic imaging, nonsurgical treatment options, and indications for surgical intervention. In this review, we will discuss the anatomic considerations of RTS, relevant physical examination findings, potential diagnostic modalities, and outcomes of several treatment options.

Cadaveric and Ultrasound Validation of Percutaneous Electrolysis Approaches at the Arcade of Frohse: A Potential Treatment for Radial Tunnel Syndrome

Entrapment of the radial nerve at the arcade of Frohse could contribute to symptoms in patients with lateral epicondylalgia or radial tunnel syndrome. Our aim was to determine the validity of applying percutaneous electrolysis, targeting the supinator muscle at the Frohse’s arcade with ultrasound imaging and in a Thiel-embalmed cadaver model (not ultrasound-guiding). Percutaneous electrolysis targeting the supinator muscle was conducted in five healthy volunteers (ultrasound study) and three Thiel-embalmed cadaver forearms. Two approaches, one with the forearm supinated and other with the forearm pronated were conducted. The needle was inserted until the tip reached the interphase of both bellies of the supinator muscle. Accurate needle penetration of the supinator muscle was observed in 100% in both US-imaging and cadaveric studies. No neurovascular bundle of the radial-nerve deep branch was pierced in any insertion. The distance from the tip of the needle to the neurovascular bundle was 15.3 ± 0.6 mm with the forearm supinated, and 11.2 ± 0.6 mm with the forearm pronated. The results of the current study support that percutaneous electrolysis can properly target the supinator muscle with either the forearm in supination or in pronation. In fact, penetration of the neurovascular bundle was not observed in any approach when percutaneous needling electrolysis was performed by an experienced clinician.

Is Dry Needling of the Supinator a Safe Procedure? A Potential Treatment for Lateral Epicondylalgia or Radial Tunnel Syndrome. A Cadaveric Study

The supinator muscle is involved in two pain conditions of the forearm and wrist: lateral epicondylalgia and radial tunnel syndrome. Its close anatomical relationship with the radial nerve at the arcade of Frohse encourages research on dry needling approaches. Our aim was to determine if a solid filiform needle safely penetrates the supinator muscle during the clinical application of dry needling. Needle insertion of the supinator muscle was conducted in ten cryopreserved forearm specimens with a 30 × 0.32 mm filiform needle. With the forearm pronated, the needle was inserted perpendicular into the skin at the dorsal aspect of the forearm at a point located 4cm distal to the lateral epicondyle. The needle was advanced to a depth judged to be in the supinator muscle. Safety was assessed by measuring the distance from the needle to the surrounding neurovascular bundles of the radial nerve. Accurate needle penetration of the supinator muscle was observed in 100% of the forearms (needle penetration:16.4 ± 2.7 mm 95% CI 14.5 mm to 18.3 mm). No neurovascular bundle of the radial nerve was pierced in any of the specimen’s forearms. The distances from the tip of the needle were 7.8 ± 2.9 mm (95% CI 5.7 mm to 9.8 mm) to the deep branch of the radial nerve and 8.6 ± 4.3 mm (95% CI 5.5 mm to 11.7 mm) to the superficial branch of the radial nerve. The results from this cadaveric study support the assumption that needling of the supinator muscle can be accurately and safely conducted by an experienced clinician.