The elastography of distal ulnar nerve branches in cyclists.

INTRODUCTION: Forced elbow flexion and pressure during bicycling result in ulnar nerve traction and pressure exerted in Guyon's canal or the nerve's distal branches. The compression of the nerves causes a change in their stiffness related to edema and eventually gradual fibrosis. PURPOSE: This study aimed to evaluate the elastography of terminal branches of the ulnar nerve in cyclists. STUDY DESIGN: Cross-sectional study. METHODS: Thirty cyclists, 32 healthy individuals, and 32 volunteers with ulnar nerve entrapment neuropathies participated in the study. Each participant underwent a nerve examination of the cubital tunnel, Guyon's canal and the deep and superficial branches of the ulnar nerve using shear wave elastography. The cyclist group was tested before and after a 2-hour-long workout. RESULTS: Before cycling workouts, the ulnar nerve stiffness in the cubital tunnel and Guyon's canal remained below pathological estimates. Cycling workouts altered nerve stiffness in the cubital tunnel only. Notably, the stiffness of the ulnar terminal branches in cyclists was increased even before training. The mean deep branch stiffness was 50.85 ± 7.60 kPa versus 20.43 ± 5.95 kPa (p < 0.001) in the cyclist and healthy groups, respectively, and the mean superficial branch stiffness was 44 ± 12.45 kPa versus 24.55 ± 8.05 kPa (p < 0.001), respectively. Cycling contributed to a further shift in all observed values. DISCUSSION: These observations indicate the existence of persistent anatomical changes in the distal ulnar branches in resting cyclists that result in increased stiffness of these nerves. The severity of these changes remains, however, to be determined. CONCLUSIONS: These data show elastography values of the ulnar terminal branches in healthy individuals and cyclists where despite lack of clinical symptoms that they seem to be elevated twice above the healthy range.

Multimodality imaging review of ulnar nerve pathologies.

The ulnar nerve is the second most commonly entrapped nerve after the median nerve. Although clinical evaluation and electrodiagnostic studies remain widely used for the evaluation of ulnar neuropathy, advancements in imaging have led to increased utilization of these newer / better imaging techniques in the overall management of ulnar neuropathy. Specifically, high-resolution ultrasonography of peripheral nerves as well as MRI has become quite useful in evaluating the ulnar nerve in order to better guide treatment. The caliber and fascicular pattern identified in the normal ulnar nerves are important distinguishing features from ulnar nerve pathology. The cubital tunnel within the elbow and Guyon's canal within the wrist are important sites to evaluate with respect to ulnar nerve compression. Both acute and chronic conditions resulting in deformity, trauma as well as inflammatory conditions may predispose certain patients to ulnar neuropathy. Granulomatous diseases as well as both neurogenic and non-neurogenic tumors can also potentially result in ulnar neuropathy. Tumors around the ulnar nerve can also lead to mass effect on the nerve, particularly in tight spaces like the aforementioned canals. Although high-resolution ultrasonography is a useful modality initially, particularly as it can be helpful for dynamic evaluation, MRI remains most reliable due to its higher resolution. Newer imaging techniques like sonoelastography and microneurography, as well as nerve-specific contrast agents, are currently being investigated for their usefulness and are not routinely being used currently.

Histological Evidence of Intrinsic Muscle Degeneration in Compression Ulnar Neuropathy.

PURPOSE: We investigated the histological characteristics of the tissues in the intrinsic hand muscles of patients with compressive ulnar neuropathy (CUN) to determine how the compromised nerve influences the target muscle. METHODS: In total, 83 patients underwent surgery for CUN in our institution between March 2015 and August 2017. Of these, 45 patients who met our inclusion/exclusion criteria were initially included in this study. Basic demographic data including age, sex, hand dominance, duration of symptoms, bone mineral density, and clinical stage were evaluated. During the ulnar nerve decompression surgery, a biopsy of the ipsilateral adductor pollicis was performed. Using the biopsy samples, we analyzed the tissue composition and degree of degeneration, and investigated the association with demographic factors and clinical status. RESULTS: The ratio of muscle/connective tissue/fat was 62.62 ± 8.27%/23.44 ± 4.10%/14.16 ± 6.68% in the affected muscle. The ratio was different than that of samples taken from control groups. In samples containing muscle fibers, although the total fat content remained low, fat was consistently concentrated at the fascicular borders, between fascicles (perifascicular fat, 62.3 ± 18.2% of fascicles), and within fascicles (intrafascicular fat, 35.6 ± 11.8% of fascicles). The proportion of centrally nucleated muscle fibers was also significantly elevated (5.58 ± 4.25%; P < 0.001) compared with that of both controls (1.09 ± 1.26%) and the clinical threshold for abnormal central nuclei (3%). Preoperative scores assessed using Gabel and Amadio criteria were positively correlated with the muscle composition (r = 0.89, P < 0.001). In addition, the clinical status was negatively correlated with the degree of fat accumulation and the proportion of centrally nucleated muscle fibers (r = -0.94, P < 0.001, r = -0.82, P < 0.001). CONCLUSIONS: We demonstrated that target muscle in CUN underwent degeneration, which was potentially exacerbated by inflammation, and that the degree of degeneration was correlated with the patient's clinical status. Histologically, reversible recovery of the hand muscles may be possible if decompression of the ulnar nerve is performed at earlier stages.

Shear-wave elastography in the diagnosis of ulnar tunnel syndrome.

An interesting alternative to traditional diagnostic techniques of the upper extremity nerve entrapments might be an ultrasound elastography that has started to gain attention in recent research. The aim of this preliminary study was to verify whether a quantitative analysis of the ulnar nerve stiffness by shear-wave elastography can be used to diagnose ulnar tunnel syndrome (UTS), an ulnar nerve neuropathy at Guyon's canal. The study included 46 patients (39 women) and 39 healthy controls (34 women). All diagnoses in patients and controls were confirmed with nerve conduction studies. Measurements of nerve stiffness were taken at three levels: Guyon's canal (G), distal forearm (DF), and mid forearm (MF). Additionally, the ulnar nerve cross-sectional area at the canal's level was determined by ultrasonography. Patients with UTS presented with significantly greater nerve stiffness than the controls (mean, 99.41 kPa vs. 49.08 kPa, P < 0.001). No significant intergroup differences were found in the nerve elasticity at DF and MF levels (P < 0.836 and P < 0.881, respectively). An ulnar nerve stiffness value of 80 kPa and G:DF and G:MF ratios equal to 1.5 provided 100% sensitivity, specificity, and positive and negative predictive values in the detection of the syndrome. The mean nerve cross-sectional area in the Guyon's canal was significantly greater in patients than in the controls (4.63 mm2, range, 2-7 mm2 vs. 3.23 mm2, range, 2-5 mm2, P < 0.001). In conclusion, we believe that shear-wave elastography has the potential to become a useful adjunct diagnostic test for UTS.

Ulnar Nerve Entrapment by an Additional Slip of the Triceps Brachii.

Additional slips of the triceps brachii have been reported in cadaver studies. We report the case of a 48-year-old man with no history of trauma who presented with a tingling sensation and weakness in his right hand. Electromyography revealed ulnar neuropathy around the elbow, with decreased conduction proximal to the medial epicondyle. On ultrasonography and magnetic resonance imaging, the ulnar nerve was found to be mildly swollen and covered by an additional slip of the triceps brachii muscle above the retrocondylar area. Upon full elbow flexion, this anatomy produced dynamic compression of the vessels surrounding the nerve. Despite conservative treatments for over 2 months, the patient had minimal symptom improvement. Decompression and anterior transposition of the ulnar nerve were performed with favorable results. Additional slips of the triceps brachii muscle can compress neurovascular structures and cause ulnar neuropathy at the elbow. Ultrasonography is useful in the evaluation of such neurovascular compression.

MR anatomy and pathology of the ulnar nerve involving the cubital tunnel and Guyon's canal.

Ulnar neuropathy is a common and frequent reason for referral to hand surgeons. Ulnar neuropathy mostly occurs in the cubital tunnel of the elbow or Guyon's canal of the wrist, and it is important for radiologists to understand the imaging anatomy at these common sites of impingement. We will review the imaging and anatomy of the ulnar nerve at the elbow and wrist, and we will present magnetic resonance imaging examples of different causes of ulnar neuropathy, including trauma, overuse, arthritis, masses and mass-like lesions, and systemic diseases. Treatment options will also be briefly discussed.

Syndrome of canal of Guyon - definition, diagnosis, treatment and complication.

Syndrome of canal of Guyon is the second after carpal tunnel syndrome, compression syndrome in the wrist. Opposite to median nerve compression, ulnar nerve compression is not very popular. However it impairs functioning of the hand even more than median nerve lesion. Authors deal with definition, possible diagnostic methods, treatment and most frequent complication.

Ulnar nerve entrapment at the wrist.

Presentation of ulnar nerve entrapment at the wrist varies based on differential anatomy and the site or sites of compression. Therefore, an understanding of the anatomy of the Guyon canal is essential for diagnosis in patients presenting with motor and/or sensory deficits in the hand. The etiologies of ulnar nerve compression include soft-tissue tumors; repetitive or acute trauma; the presence of anomalous muscles and fibrous bands; arthritic, synovial, endocrine, and metabolic conditions; and iatrogenic injury. In addition to a thorough history and physical examination, which includes motor, sensory, and vascular assessments, imaging and electrodiagnostic studies facilitate the diagnosis of ulnar nerve lesions at the wrist. Nonsurgical management is appropriate for a distal compression lesion caused by repetitive activity, but surgical decompression is indicated if symptoms persist or worsen over 2 to 4 months.

Anatomy of Guyon's canal - a systematic review.

Carpal tunnel syndrome is the first on the list of peripheral nerve lesions in the upper limb. Most of the anatomical facts about this syndrome are widely known. The Guyoun's canal is the second reason for compression syndrome in the wrist. Anatomy of this is region still remains controversial. This is why authors tried to compile some latest findings accompanied by their own observation, and added some clinical notes, which might be useful both for orthopedic surgeons and well as for representatives of basic sciences.

Unusual presentation of multiple nerve entrapment: a case report.

Cubital tunnel syndrome is the most common form of ulnar nerve entrapment and the second most common entrapment neuropathy of the upper extremity after carpal tunnel syndrome. However, bilateral compressive ulnar neuropathy is a rare condition. Electro diagnostic studies are a valid and reliable means of confirming the diagnosis.

Development and validation of the patient-rated ulnar nerve evaluation.

BACKGROUND: Compression neuropathy at the elbow causes substantial pain and disability. Clinical research on this disorder is hampered by the lack of a specific outcome measure for this problem. A patient-reported outcome measure, The Patient-Rated Ulnar Nerve Evaluation (PRUNE) was developed to assess pain, symptoms and functional disability in patients with ulnar nerve compression at the elbow. METHODS: An iterative process was used to develop and test items. Content validity was addressed using patient/expert interviews and review; linking of the scale items to International Classification of Functioning, Disability, and Health (ICF) codes; and cognitive coding of the items. Psychometric analysis of data collected from 89 patients was evaluated. Patients completed a longer version of the PRUNE at baseline. Item reduction was performed using statistical analyses and patient input to obtain the final 20 item version. Score distribution, reliability, exploratory factor analysis, correlational construct validity, discriminative known group construct validity, and responsiveness to change were evaluated. RESULTS: Content analysis indicated items were aligned with subscale concepts of pain and sensory/motor symptoms impairments; specific upper extremity-related tasks; and that the usual function subscale provided a broad view of self-care, household tasks, major life areas and recreation/ leisure. Four subscales were demonstrated by factor analysis (pain, sensory/motor symptoms impairments, specific activity limitations, and usual activity/role restrictions). The PRUNE and its subscales had high reliability coefficients (ICCs>0.90; 0.98 for total score) and low absolute error. The minimal detectable change was 7.1 points. It was able to discriminate between clinically meaningful subgroups determined by an independent evaluation assessing work status, residual symptoms, motor recovery, sensory recovery and global improvement) p<0.01. Responsiveness was excellent (SRM=1.55). CONCLUSION: The PRUNE is a brief, open-access, patient-reported outcome measure for patients with ulnar nerve compression that demonstrates strong measurement properties.

T2-signal of ulnar nerve branches at the wrist in guyon's canal syndrome.

OBJECTIVE: To evaluate T2-signal of high-resolution MRI in distal ulnar nerve branches at the wrist as diagnostic sign of guyon's-canal-syndrome (GCS). MATERIALS AND METHODS: 11 GCS patients confirmed by clinical/electrophysiological findings, and 20 wrists from 11 asymptomatic volunteers were prospectively included to undergo the following protocol: axial T2-weighted-fat-suppressed and T1-weighted-turbo-spin-echo-sequences (3T-MR-scanner, Magnetom/Verio/Siemens). Patients were examined in prone position with the arm extended and wrist placed in an 8-channel surface-array-coil. Nerve T2-signal was evaluated as contrast-to-noise-ratios (CNR) from proximal-to-distal in ulnar nerve trunk, its superficial/sensory and deep/motor branch. Distal motor-nerve-conduction (distal-motor-latency (dml)) to first dorsal-interosseus (IOD I) and abductor digiti minimi muscles was correlated with T2-signal. Approval by the institutional review-board and written informed consent was given by all participants. RESULTS: In GCS, mean nerve T2-signal was strongly increased within the deep/motor branch (11.7±4.8 vs.controls:-5.3±2.4;p = 0.001) but clearly less and not significantly increased in ulnar nerve trunk (6.8±6.4vs.-7.4±2.5;p = 0.07) and superficial/sensory branch (-2.1±4.9vs.-9.7±2.9;p = 0.08). Median nerve T2-signal did not differ between patients and controls (-9.8±2.5vs.-6.7±4.2;p = 0.45). T2-signal of deep/motor branch correlated strongly with motor-conduction-velocity to IOD I in non-linear fashion (R(2) = -0.8;p<0.001). ROC-analysis revealed increased nerve T2-signal of the deep/motor branch to be a sign of excellent diagnostic performance (area-under-the-curve 0.94, 95% CI: 0.85-1.00; specificity 90%, sensitivity 89.5%). CONCLUSIONS: Nerve T2-signal increase of distal ulnar nerve branches and in particular of the deep/motor branch is highly accurate for the diagnostic determination of GCS. Furthermore, for the first time it was found in nerve entrapment injury that T2-signal strongly correlates with electrical-conduction-velocity.

Variation of the proximal insertion of the abductor digiti minimi muscle: correlation with Guyon's canal syndrome? Case report and literature review.

We describe the case of an original insertion and course of the abductor digiti minimi muscle on the medial part of the palmaris longus tendon. The anomalous muscle was only present on the left side. Various studies have reported the frequency of anomalous muscles in approximately 22 to 35% of hands and it was in majority an anomalous abductor digiti minimi muscle. The knowledge of this original insertion is important because it can sometimes be correlated with ulnar nerve compression at Guyon's canal. But Guyon's canal syndrome is less common than carpal tunnel syndrome, and the incidence of ulnar nerve compression in relation with anomalous muscle is approximately 2.9% of cases. It is possible to diagnose the anomalous muscle through ultrasound or MRI. This variation should be taken into consideration by surgeons during surgical procedures for ulnar nerve decompression at Guyon's canal and when performing anteromedial approach to the wrist between flexors tendons and ulnar bundle.

Nerves of the hand beyond the carpal tunnel.

Imaging studies including ultrasound (US) and magnetic resonance imaging may be required to evaluate the median nerve in patients with suspected carpal tunnel syndrome. However, the radial and ulnar nerves contribute to sensory and motor innervations to the hand as well. Compressive, traumatic, and iatrogenic events may damage the small terminal branches of these nerves. In the hand, US is able to identify injuries of the median, ulnar, radial nerve, and terminal branches. This article presents the role of imaging to evaluate the nerves of the hand with an emphasis on US. Due to its high-resolution capabilities, US is useful to determine the location, extent, and type of nerve lesion. Moreover, US is useful for a postsurgical assessment. The anterior interosseous nerve, Guyon's tunnel syndrome, and Wartenberg's syndrome are also described.

Imaging of ulnar-sided wrist pain.

Pain on the ulnar side of the wrist is a complex diagnostic dilemma. This is mainly due to the small size and complexity of the anatomical structures. The issue is compounded by the occurrence of positive imaging findings that are clinically asymptomatic. This pictorial essay deals with the imaging manifestations of different causes of ulnar-sided wrist pain.

The Guyon's canal in perspective: 3-T MRI assessment of the normal anatomy, the anatomical variations and the Guyon's canal syndrome.

PURPOSES: (1) To revisit the anatomical boundaries of the canal, its contents and its two channels, (2) to describe the anatomical variations of the canal's borders and the variations of its contents, and (3) to discuss the clinical relevance of the Guyon's canal syndrome. METHODS: Two hundred and fifty MR wrists examinations were reviewed. MR spin echo T1-weighted axial slices were used to analyze the Guyon's canal. The anatomical boundaries, the cross-sectional area and length of the canal were calculated. The anatomical variations of the canal's walls and contents and their prevalence were sought. Changes related to Guyon's canal syndrome were also evaluated. RESULTS: From the 250 wrists, the anatomy of the Guyon's canal was normal in 168 (67.2%) wrists; 73 (29.2%) wrists presented with anatomical variations; and 9 (3.6%) wrists had derangements causing Guyon's canal syndrome. The cross-sectional area of the canal was 33 ± 11 mm² proximally and 45 ± 19 mm² distally. The canal's length was approximately 40 ± 4 mm. Among the 73 wrists with anatomical variations, there were aberrant muscles in 39 (53.4%) wrists, multiple ulnar nerve branching in 22 (30%) cases, increased amount of fat tissue inside the canal in 9 (12.3%) cases and hypoplastic hamulus in 3 (4.1%) cases. There were 9 (3.6%) symptomatic wrists with clinical and radiological features attributed to Guyon's canal syndrome. CONCLUSION: MRI is an excellent modality for the evaluation of the Guyon's canal.

Dysplasia epiphysealis hemimelica of the elbow.

Dysplasia epiphysealis hemimelica (DEH) or Trevor's disease is a rare disorder affecting the epiphyses and short bones of the limbs, and characterized by a benign overgrowth of the medial-half of the epiphysis resembling osteochondroma. Upper limb involvement is very rare and most commonly affects the carpal bones. Only five established cases of DEH around the elbow were found in the orthopedic literature. We herein report an additional case of Trevor's disease of the elbow in a child with a symptomatic ulnar nerve compression and its management. To the best of our knowledge, this is the first case of DEH of the elbow presenting with nerve compromise.