Ultrasound-guided minimally invasive thread release of Guyon's canal: initial experience in cadaveric specimens.

OBJECTIVE: Guyon's canal syndrome is caused by compression of the ulnar nerve at the wrist, occasionally requiring decompression surgery. In recent times, minimally invasive approaches have gained popularity. The aim of this study was to assess the efficacy and safety of ultrasound-guided thread release for transecting the palmar ligament in Guyon's canal without harming surrounding structures, in a cadaveric specimen model. METHODS: After ethical approval, thirteen ultrasound-guided thread releases of Guyon's canal were performed on the wrists of softly embalmed anatomic specimens. Cadavers showing injuries or prior operations at the hand were excluded. Subsequently, the specimens were dissected, and the outcome of the interventions and potential damage to adjacent anatomical structures as well as ultrasound visibility were evaluated with a score from one to three. RESULTS: Out of 13 interventions, a complete transection was achieved in ten cases (76.9%), and a partial transection was documented in three cases (23.1%). Irrelevant lesions on the flexor tendons were observed in two cases (15.4%), and an arterial branch was damaged in one (7.7%). Ultrasound visibility varied among specimens, but essential structures were delineated in all cases. CONCLUSION: Ultrasound-guided thread release of Guyon's canal has shown promising first results in anatomic specimens. However, further studies are required to ensure the safety of the procedure. RELEVANCE STATEMENT: Our study showed that minimally invasive ultrasound-guided thread release of Guyon's canal is a feasible approach in the anatomical model. The results may provide a basis for further research and refinement of this technique. KEY POINTS: • In Guyon's canal syndrome, the ulnar nerve is compressed at the wrist, often requiring surgical release. • We adapted and tested a minimally invasive ultrasound-guided thread release technique in anatomic specimens. • The technique was effective; however, in one specimen, a small anatomic branch was damaged.

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.

Diagnosis of ulnar nerve entrapment anterior to the medial epicondyle by ultrasound elastography and diffusion tensor imaging with fiber tractography: a case report.

Ulnar/cubital tunnel syndrome is the second most common compressive neuropathy of the upper limb. Permanent location of the ulnar nerve anterior to the medial epicondyle is extremely rare, with only five cases reported in the literature. Using ultrasound elastography and diffusion tensor imaging with fiber tractography, we diagnosed a case in which ulnar nerve entrapment was associated with anterior nerve location. Surgical release confirmed the diagnosis and the patient was symptom free 3 months after surgery.

Cycling-Related Compressive Neuropathy of the Deep Ulnar Motor Branch in the Hand: Is Sonography a Valid Tool?

Repetitive vibratory trauma in cyclists is one of the most common causes of ulnar nerve compression at the wrist. This study describes five cases of clinically suspected compression syndrome of the deep terminal branch of the ulnar nerve (DBUN) defined by high-resolution ultrasound (HRUS) with a 18-MHz linear transducer. Reliable HRUS visualization of the DBUN was feasible in all patients. The affected nerves had focally swollen and hypo-echoic changed segments. HRUS is a good imaging tool for the evaluation of a suspicious DBUN neuropathy if no electrodiagnostic testing is available or in patients with mild to moderate clinical symptoms with inconclusive electrodiagnostic results.

Patterns and parameters describing nerve thickening in compression and entrapment ulnar neuropathies at the elbow.

OBJECTIVE: To compare pattern and parameters describing nerve thickening in ulnar neuropathy at the elbow (UNE) due to external compression in the retrocondylar groove (RTC), and entrapment under the humeroulnar aponeurosis (HUA). METHODS: In a group of our previously reported UNE patients we ultrasonographically (US) measured ulnar nerve cross-sectional areas (CSA) on 6-8 standard locations in the elbow segment. We compared CSA patterns in both groups, and determined diagnostic utility of selected CSA based parameters. RESULTS: We studied 79 patients (81 arms) with UNE due to external compression, and 53 patients (55 arms) due to entrapment. Maximal ulnar nerve CSA (>16 mm2), maximal CSA change (>7 mm2/1-2 cm) and maximal/minimal CSA ratio (>2.6) were significantly larger in UNE due to entrapment. They also differentiated these arms from arms with compression with sensitivities of 78%, 87% and 80%, and specificities of 90%, 94%, and 85%, respectively. CONCLUSION: Maximal difference in CSA between points separated by 1-2 cm (>7 mm2/1-2 cm) very efficiently differentiated between UNE due to external compression and entrapment. SIGNIFICANCE: The proposed parameter will hopefully complement precise localization in determining underlying mechanism of UNE. This may help physicians to determine the most appropriate treatment for UNE and possibly other focal neuropathies of unknown cause; i.e., conservative treatment for external compression and surgery for entrapment.

Isolated compression of the ulnar motor branch due to carpal joint ganglia: clinical series, surgical technique and postoperative outcomes.

The entrapment of the ulnar nerve in Guyon's canal (GC) is a well-known wrist canalicular syndrome which is usually followed by a gradual combination of both sensitive and motor symptomatology. However, GC nerve compression could also cause a pure hand motor dysfunction. This condition, less frequent than the classic Guyon's syndrome, can be difficult to diagnose. Authors report a case series of eight patients affected by isolated compression of the ulnar nerve motor branch, due to piso-triquetrum or triquetro-hamate joint ganglia. Surgical technique and postoperative outcomes are discussed in this paper. The isolated compression of the ulnar nerve motor branch is a very rare clinical condition which is often linked to several causes. The rarity of the pathology is probably due to lack of knowledge and therefore to the difficulty in formulating a correct diagnosis. Surgical treatment appears to be decisive in most cases, although late diagnosis often leads to incomplete functional recovery.

Innervation of the anconeus epitrochlearis muscle: MRI and cadaveric studies.

Ulnar neuropathy at the cubital tunnel is common. However, a rare form of ulnar neuropathy here is due to compression from an accessory muscle, the anconeus epitrochlearis. Reports in the literature regarding the details of this muscle's innervation are vague, so the aim of the present study was to characterize this anatomy more clearly. This was a combined review of magnetic resonance imaging (MRI) from patients with an anconeus epitrochlearis and ulnar neuropathy and cadaveric dissections to characterize the innervation of this variant muscle. A review of 11 patients and three reports of ulnar neuropathy and an anconeus epitrochlearis in the literature revealed no MRI changes consistent with acute denervation of this muscle. However, in two cases, there were signs of chronic denervation of the muscle. Dissection of five cadavers revealed that the nerve supply to the anconeus epitrochlearis originated proximal to the medial epicondyle, traveled parallel to the ulnar nerve, terminated on the deep aspect of this muscle, and had a mean length of 60 mm. This clinicoanatomical study provides evidence that the innervation of the anconeus epitrochlearis is proximal to the muscle and on its deep aspect. Clin. Anat. 32:218-223, 2019. © 2018 Wiley Periodicals, Inc.

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.

Shear-wave elastography: a new potential method to diagnose ulnar neuropathy at the elbow.

OBJECTIVES: The primary aim of this study was to verify if shear-wave elastography (SWE) can be used to diagnose ulnar neuropathy at the elbow (UNE). The secondary objective was to compare the cross-sectional areas (CSA) of the ulnar nerve in the cubital tunnel and to determine a cut-off value for this parameter accurately identifying persons with UNE. METHODS: The study included 34 patients with UNE (mean age, 59.35 years) and 38 healthy controls (mean age, 57.42 years). Each participant was subjected to SWE of the ulnar nerve at three levels: in the cubital tunnel (CT) and at the distal arm (DA) and mid-arm (MA). The CSA of the ulnar nerve in the cubital tunnel was estimated by means of ultrasonographic imaging. RESULTS: Patients with UNE presented with significantly greater ulnar nerve stiffness in the cubital tunnel than the controls (mean, 96.38 kPa vs. 33.08 kPa, p < 0.001). Ulnar nerve stiffness of 61 kPa, CT to DA stiffness ratio equal 1.68, and CT to MA stiffness ratio of 1.75 provided 100% specificity, sensitivity, positive and negative predictive value in the detection of UNE. Mean CSA of the ulnar nerve in the cubital tunnel turned out to be significantly larger in patients with UNE than in healthy controls (p < 0.001). A weak positive correlation was found in the UNE group between the ulnar nerve CSA and stiffness (R = 0.31, p = 0.008). CONCLUSIONS: SWE seems to be a promising, reliable and simple quantitative adjunct test to support the diagnosis of UNE. KEY POINTS: • SWE enables reliable detection of cubital tunnel syndrome • Significant increase of entrapped ulnar nerve stiffness is observed in UNE • SWE is a perspective screening tool for early detection of compressive neuropathies.

Comparison of Ultrasonography and Short-Segment Nerve Conduction Study in Ulnar Neuropathy at the Elbow.

OBJECTIVE: To assess the correlation between ultrasonographic and electrodiagnostic findings to determine the localization of the ulnar trapping at the elbow. DESIGN: Cross-sectional and noninterventional trial. SETTING: Physical medicine and rehabilitation department of a teaching hospital. PARTICIPANTS: Patients (N=14) diagnosed with ulnar nerve entrapment using short-segment nerve conduction study. INTERVENTIONS: The elbow area was divided into 4 segments with 2-cm intervals. All patients underwent ultrasonographic and electrodiagnostic examinations. MAIN OUTCOME MEASURES: The nerve conduction velocity (NCV) of each segment was measured. The cross-sectional area (CSA) of the ulnar nerve was measured at 5 levels. The proximal CSA/distal CSA ratio (PDR) was calculated by proportioning the CSA values for each segment. The highest PDR was accepted as a trapping segment, whereas the segment with the lowest NCV was accepted electrophysiologically (provided it was <50m/s). RESULTS: A total of 80 PDR and NCV measurements were taken from 20 elbows. A statistically significant negative correlation (r=-.554; P<.001) was found between general PDR and NCV values. When we assumed that the NCV value <50m/s as the criterion standard for diagnosis, the cutoff value for the PDR was found to be 1.08, with a sensitivity of 70% and a specificity of 92.5%. The minimum NCV value and the maximum PDR value were mostly seen in the third segment compatible with the cubital tunnel. CONCLUSIONS: Ultrasonography seems to be advantageous because it is more comfortable for the patient and requires shorter time than does electroneuromyography. To our knowledge, this is the first study to detect ulnar nerve entrapment by using not only CSA but also PDR as a ratio method with ultrasound.

Unusual case of hypotenar Hammer Syndrome and carpal tunnel syndrome association.

BACKGROUND AND AIM OF THE WORK: Hypothenar Hammer Syndrome is a relatively rare disease process caused by repetitive stress or injury to the hypothenar eminence leading to chronic injury to the ulnar artery. Our study reports an unusual case. METHODS: A 57 years old Plumber presented in April 2016 with a history of constant pain and recurrent paresthesia involving the fingers of the right hand for several months, over the previous 1 year, his hand had become more intolerant of exposure to cold temperatures. Angio-RNM and electromyography were performed and showed a severe double compression of ulnar and median nerve and an ulnar artery deformity without thrombosis. Surgery was performed under sedation and axillary anesthesia. RESULTS: After surgery patient' symptoms immediately improved, and within a few months, his hand had normalized. CONCLUSION: Hypothenar Hammer Syndrome is a rare disease process which manifests in certain occupations and activities that put undue stress on the hypothenar area. Furthermore, the carpal tunnel syndrome, a pressure damage of the median nerve, caused by repetitive manual tasks with flexion and extension of wrist has been added as well as hypothenar hammer syndrome which are vascular damages of hand caused by shock-type application of force.

Ultrasound biomechanical anatomy of the soft structures in relation to the ulnar nerve in the cubital tunnel of the elbow.

BACKGROUND: Chronic ulnar nerve entrapment worsened by elbow flexion is the most common injury, but rare painful conditions may also be related to ulnar nerve instability. The posterior bundle of the medial collateral ligament (pMCL) and the retinaculum, respectively form a soft floor and a ceiling for the cubital tunnel. The aim of our study was to dynamically assess these soft structures of the cubital tunnel focusing on those involved in the biomechanics of the ulnar nerve. METHODS: Forty healthy volunteers had a bilateral ultrasonography of the cubital tunnel. Elbows were scanned in full extension, 45° and 90°, and maximal passive flexion. Morphological changes of the nerve and related structures were dynamically assessed on transverse views. RESULTS: Both the pMCL and the retinaculum tightened with flexion. During elbow flexion, the tightening of the pMCL superficially moved the ulnar nerve remote from the osseous floor of the retroepicondylar groove. A retinaculum was visible in all 69 tunnels with stable nerves (86.3%), tightened in flexion, but absent in 11 tunnels with unstable nerves (13.7%). The retinaculum was fibrous in 60 elbows and muscular in nine, the nine muscular variants did not significantly influence the biomechanics of stable nerves. Stable nerves flattened in late flexion between the tightened pMCL and retinaculum, whereas unstable nerves transiently flattened when translating against the anterior osseous edge of the groove. CONCLUSION: The retinaculum and the pMCL are key structures in the biomechanics of the ulnar nerve in the cubital tunnel of the elbow.

Intraneural microcystic lymphatic malformation of the ulnar nerve at the Guyon canal: Unusual cause of ulnar pain in a child.

We present a case of an unusual cause of ulnar pain on a 9-year-old patient. The patient had pain on the ulnar side of the wrist after a fall. MRI showed a poorly defined lesion on the ulnar nerve at Guyon's canal. The initial diagnosis was traumatic neuropathy. Following conservative treatment of symptoms for one year, the pain started again. Therefore, a new MRI was performed where progression of the lesion was observed. Excision of the lesion was performed and the specimen sent for pathologic analysis. The diagnosis was of microcystic lymphatic malformation. The patient had a satisfactory evolution, with complete resolution. This is the first description of a microcystic lymphatic malformation in an intraneuronal location.