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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). 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. 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%). 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.

This study aimed to histologically investigate whether the compatibility of donor and recipient nerves in distal nerve transfer for radial and ulnar nerve palsy is suitable for restoring nerve function. Partial median to radial nerve transfer for radial nerve palsy and partial median to ulnar nerve transfer for ulnar nerve palsy were performed in 10 cadaveric upper limbs fixed using the Thiel technique. Histological analysis of the nerve samples at the coaptation site focused on the number of myelinated axons. Each recipient and donor nerve was identified in all specimens without any anatomical variations. While median-radial nerve transfer techniques showed an adequate number of donor axons, median-ulnar nerve transfer techniques showed a shortage of donor axons. The insufficiency of donor axons compared to the recipient axons may explain the challenges in reinnervating the recipient muscles. Combining the two different nerve transfers may compensate for the shortage of donor axons and improve motor recovery. Type of study and Level of evidence: Therapeutic, Level III.

BackgroundNeedle trauma has been associated with peripheral nerve injury and neurological dysfunction. However, inadvertent needle puncture is frequent while postblock dysfunction is rare. We conducted a cadaveric study to evaluate the association between needle puncture and fascicular injury.MethodsFive median and five ulnar (isolated) nerves were obtained from fresh human cadavers. Four different needles were used for the transfixing punctures: A 30° beveled (22G) nerve block needle, and 15° beveled (22G, 25G and 27G) Quincke spinal block needles. 10 transfixing punctures were made with each needle type on each nerve (40 punctures per nerve). Samples were then immersed in 5% formaldehyde solution for 30 days. Perpendicular cross-sections of the punctured segments were obtained. Samples were embedded in paraffin and analyzed under light microscopy with H&E staining. On each slice, the following variables were obtained: ratio of fascicular/epineurial tissue, the number of fascicles per nerve and the number of injured fascicles.ResultsA total of 400 punctures were made (200 median and 200 ulnar) and 144 histological nerve sections analyzed (74 median and 70 ulnar). The median number of fascicles per section was 16 (range 7–23) and 17 (range 8–27) with a fascicular/epineural tissue ratio of 45% (range 35%–52%) and 44% (range 39%–54%) for median and ulnar, respectively. Three fascicular injuries were identified: one in ulnar and two in median. All injuries were caused by a 15° beveled needle, the ulnar with a 22G and the median with a 22G and a 27G.ConclusionsFascicular injury is rare following needle transfixion. Needle injury alone is unlikely to explain postblock neurological dysfunction.

Leprosy is the most common treatable peripheral neuropathy worldwide. The detection of peripheral nerve impairment is essential for its diagnosis and treatment, in order to prevent stigmatizing deformities and disabilities. This study was performed to identify neural thickening through multisegmental ultrasound (US). We assessed US measurements of cross-sectional areas (CSAs) of ulnar, median and tibial nerves at two points (in the osteofibrous tunnel and proximal to the tunnel), and also of the common fibular nerve at the fibular head level in 53 leprosy patients (LP), and compared with those of 53 healthy volunteers (HV), as well as among different clinical forms of leprosy. US evaluation detected neural thickening in 71.1% (38/53) of LP and a mean number of 3.6 enlarged nerves per patient. The ulnar and tibial were the most frequently affected nerves. All nerves showed significantly higher measurements in LP compared with HV, and also greater asymmetry, with significantly higher values for ulnar and tibial nerves. We found significant CSAs differences between tunnel and pre-tunnel points for ulnar and tibial nerves, with maximum values proximal to the tunnel. All clinical forms of leprosy evaluated showed neural enlargement through US. Our findings support the role of multisegmental US as a useful method for diagnosing leprosy neuropathy, revealing that asymmetry, regional and non-uniform thickening are characteristics of the disease. Furthermore, we observed that neural involvement is common in different clinical forms of leprosy, reinforcing the importance of including US evaluation of peripheral nerves in the investigation of all leprosy patients.

Peripheral nerve injuries involving nerve defects remain challenging to treat. Although autologous nerve grafting is considered the gold standard, it has notable limitations, including donor site morbidity. To address this, we developed a scaffold-free Bio 3D conduit composed of human umbilical cord–derived mesenchymal stromal cells (UC-MSCs) using bioprinting technology. In this study, we evaluated its efficacy and safety in a canine ulnar nerve defect model. At 10 weeks postoperatively, the Bio 3D group showed better motor and sensory recovery compared with the allograft group, as demonstrated by the pinprick test, electrophysiological studies, and hypothenar muscle wet weight (0.978 ± 0.100 vs. 0.637 ± 0.151, n = 3). Morphometric analysis revealed greater axonal regeneration, including larger myelinated axon diameters (4.27 ± 0.342 µm vs. 3.69 ± 0.161 µm, n = 3) and thicker myelin sheaths (0.621 ± 0.088 µm vs. 0.497 ± 0.021 µm, n = 3). Immunostaining showed that the number of transplanted UC-MSCs diminished over time, likely after exerting their therapeutic effects. No adverse events, systemic abnormalities, or distant human cell migration was observed. These findings suggest that UC-MSC–derived Bio 3D conduits are a promising alternative for peripheral nerve regeneration, especially for patients wishing to avoid donor nerve harvesting.

Metastatic peripheral nerve lymphomas are rare, often mimicking benign neurogenic tumors or neuropraxic injuries. While some report on the involvement of nerves in the upper and lower extremities, the majority of lymphomas involve the lower extremities, with the sciatic nerve being the most common. Furthermore, involvement of the ulnar nerve is exceedingly rare, with only four reported cases, each of which indicated a primary lesion. In this article, we report a unique case of recurrent B-cell lymphoma with metastatic disease of the ulnar nerve in a nonagenarian with a remote history of diffuse high-grade large B-cell lymphoma. The patient presented with 2 months of numbness, tingling, and weakness in her left ring and small fingers. Additionally, she reported a left distal forearm mass. Examination revealed sensory loss, atrophy, and clawing of the hand. Magnetic resonance imaging showed a mass involving the ulnar nerve, confirmed as lymphoma via biopsy. Treatment included radiotherapy and capsulodeses, given her desire for a functional return to her independent activities of daily living. She was satisfied with the outcome of her management. While uncommon, this case highlights the importance of considering metastatic disease as a presentation mimicking cubital tunnel syndrome for timely diagnosis and improved outcomes. By documenting this presentation, this report aims to raise awareness among orthopedic surgeons to enhance diagnostic and management strategies for similar cases of metastatic nature and advanced patient age.

Diabetic polyneuropathy (DPN) is one of the major complications of diabetes mellitus. Ultrasound has been frequently used for evaluation of peripheral nerves. However, there are few studies that have evaluated multiple peripheral nerves in DPN. In this study, ultrasonographic features of multiple peripheral nerves in upper and lower extremities of DPN patients were investigated and compared with those of healthy controls. This study was a case–control study that enrolled 20 patients with confirmed diagnosis of DPN and 20 healthy controls. The ultrasonography was performed on the sural, tibial, fibular, sciatic, median, ulnar, radial, and musculocutaneous nerves. Nerve cross-sectional area (CSA) was measured at multiple points for each peripheral nerve. The CSAs were compared between DPN and control groups, and analyzed in relation to the clinical characteristics and electrophysiologic findings. The CSAs were significantly larger in the DPN group for sural nerve, fibular nerve at the fibular head level, median nerve at the carpal tunnel and mid-humerus level, ulnar nerve at the cubital tunnel outlet and mid-humerus level, and radial nerve at the spiral groove. The CSAs of sural nerve, tibial nerve and median nerve were significantly correlated with electrophysiologic findings. The sural nerve CSA revealed significant correlation with HbA1c. These results suggest that the ultrasonography can provide useful information in diagnosis and evaluation of DPN.

Neurological involvement occurs throughout the leprosy clinical spectrum and is responsible for the most feared consequences of the disease. Ultrasonography (US) provides objective measurements of nerve thickening and asymmetry. We examined leprosy patients before beginning multi-drug therapy aiming to describe differences in US measurements between classification groups and between patients with and without reactions. Eleven paucibacillary (PB) and 85 multibacillary (MB) patients underwent nerve US. Twenty-seven patients had leprosy reactions (type 1, type 2 and/or acute neuritis) prior to US. The ulnar (at the cubital tunnel-Ut-and proximal to the tunnel-Upt), median (M) and common fibular (CF) nerves were scanned to measure cross-sectional areas (CSAs) in mm2 and to calculate the asymmetry indexes ΔCSA (absolute difference between right and left CSAs) and ΔUtpt (absolute difference between Upt and Ut CSAs). MB patients showed greater (p<0.05) CSAs than PB at Ut (13.88±11.4/9.53±6.14) and M (10.41±5.4/6.36±0.84). ΔCSAs and ΔUtpt were similar between PB and MB. The CSAs, ΔCSAs and ΔUtpt were similar between PB patients with reactions compared to PB patients without reactions. MB patients with reactions showed significantly greater CSAs (Upt, Ut and M), ΔCSAs (Upt and Ut) and ΔUtpt compared to MB patients without reactions. PB and MB showed similar frequencies of abnormal US measurements. Patients with reactions had higher frequency of nerve thickening and similar frequency of asymmetry to those without reactions. This is the first study to investigate differences in nerve involvement among leprosy classification groups using US before treatment. The magnitude of thickening was greater in MB and in patients with reactions. Asymmetry indexes were greater in patients with reactions and did not significantly differ between PB and MB, demonstrating that asymmetry is a characteristic of leprosy neuropathy regardless of its classification.

Macrodactyly is a congenital malformation characterized by aggressive overgrowth of multiple tissues, including subcutaneous fat, nerves, and bones in digits or limbs. In type II macrodactyly, the peripheral nerve is enlarged; however, the morphological and functional characteristics of the affected peripheral nerves have rarely been evaluated. In this research, six macrodactyly patients and three polydactyly patients (control) were studied. Pre-operative sensory nerve action potential and intra-operative nerve action potential tests were performed. The microstructure and ultrastructure of the enlarged nerves were observed and neurofilament (NF) expression was evaluated using immunofluorescent staining. Axon impairment of the digital nerves originating from the median nerve (MN) was observed. A compensatory reinnervation from the ulnar nerve (UN) was found in two of the six patients, and significant morphological changes were observed in the enlarged nerve. The myelinated nerve fibers decreased, the lamellar structure of the myelin sheath changed, and the density of the NFs of the unmyelinated fibers decreased. There was aberrant distribution of NFs in the macrodactylous nerve tissues. In patients with compensatory UN reinnervation, the number of myelinated and unmyelinated fibers increased to normal levels; however, the diameter of the myelinated fibers apparently decreased. The morphology and function of the macrodactylous enlarged nerve was impaired in type II macrodactyly patients; however, the unaffected UN partially compensated for the lost function of the affected MN under specific situations. Electrophysiological tests should be performed to determine the function of the affected nerve and surgical treatment for type II macrodactyly could be refined.

Objectives MR neurography, diffusion tensor imaging (DTI) and tractography at 3 Tesla were evaluated for the assessment of patients with ulnar neuropathy at the elbow (UNE). Methods Axial T2-weighted and single-shot DTI sequences (16 gradient encoding directions) were acquired, covering the cubital tunnel of 46 patients with clinically and electrodiagnostically confirmed UNE and 20 healthy controls. Cross-sectional area (CSA) was measured at the retrocondylar sulcus and FA and ADC values on each section along the ulnar nerve. Three-dimensional nerve tractography and T2-weighted neurography results were independently assessed by two raters. Results Patients showed a significant reduction of ulnar nerve FA values at the retrocondylar sulcus ( p  = 0.002) and the deep flexor fascia ( p  = 0.005). At tractography, a complete or partial discontinuity of the ulnar nerve was found in 26/40 (65 %) of patients. Assessment of T2 neurography was most sensitive in detecting UNE (sensitivity, 91 %; specificity, 79 %), followed by tractography (88 %/69 %). CSA and FA measurements were less effective in detecting UNE. Conclusion T2-weighted neurography remains the most sensitive MR technique in the imaging evaluation of clinically manifest UNE. DTI-based neurography at 3 Tesla supports the MR imaging assessment of UNE patients by adding quantitative and 3D imaging data. Key Points • DTI and tractography support conventional MR neurography in the detection of UNE • Regionally reduced FA values and discontinuous tractography patterns indicate UNE • T2-weighted MR neurography remains the imaging gold standard in cases of UNE • DTI-based ulnar nerve tractography offers additional topographic information in 3D