Improved visualization of median, ulnar nerves, and small branches in the wrist and palm using contrast-enhanced magnetic resonance neurography.

Background: Magnetic resonance imaging of peripheral nerves in the wrist and palm is challenging due to the small size, tortuous course, complex surrounding tissues, and accompanying blood vessels. The occurrence of carpal palmar lesions leads to edema, swelling, and mass effect, which may further interfere with the display and identification of nerves. Objective: To evaluate whether contrast-enhanced magnetic resonance neurography (ceMRN) improves the visualization of the morphology and pathology of the median, ulnar nerves, and their small branches in the wrist and palm. Design: An observational study. Methods: In total 57 subjects, including 36 volunteers and 21 patients with carpal palmar lesions, were enrolled and underwent ceMRN and non-contrast MRN (ncMRN) examination at 3.0 Tesla. The degree of vascular suppression, nerve visualization, diagnostic confidence, and lesion conspicuity was qualitatively assessed by two radiologists. Kappa statistics were obtained for inter-reader agreement. The signal-to-noise ratio, contrast ratio (CR), and contrast-to-noise ratio (CNR) of the median nerve were measured. The subjective ratings and quantitative measurements were compared between ncMRN and ceMRN. Results: The inter-reader agreement was excellent (k > 0.8) for all qualitative assessments and visualization assessment of each nerve segment. Compared with ncMRN, ceMRN significantly improved vascular suppression in volunteers and patients (both p < 0.001). The ceMRN significantly enhanced nerve visualization of each segment (all p < 0.05) and diagnostic confidence in volunteers and patients (both p < 0.05). The ceMRN improved lesion conspicuity (p = 0.003) in patients. Quantitatively, ceMRN had significantly higher CRs of nerve versus subcutaneous fat, bone marrow, and vessels and CNR of nerve versus vessel than ncMRN (all p < 0.05). Conclusion: The ceMRN significantly improves the visualization of peripheral nerves and pathology in the wrist and palm by robustly suppressing the signals of fat, bone marrow, and especially vessels in volunteers and patients.

Study on the improvement of magnetic resonance imaging and lesion display of small nerves in the wrist and palm using contrast agents Why was the study done? Because the nerves and branches in the wrist and palm are numerous, small, tortuous, and surrounded by muscles, fat, bones, blood vessels and other tissues, it is difficult to show their complete shape with conventional magnetic resonance imaging. Hand lesions often lead to swelling, edema and masses, which interfere with the display of nerves. Therefore, it is difficult to directly diagnose the relationship between the lesions and nerves in clinical practice. What did the researchers do? The research team used contrast agent plus three-dimensional high-resolution magnetic resonance sequence to display the nerves of volunteers and patients with hand lesions, and used subjective and objective evaluation methods to compare the display effect of the sequence on the nerves before and after the use of contrast agent. What did the researchers find? The imaging method of contrast agent plus three-dimensional high-resolution magnetic resonance sequence can reduce the interference of fat, blood vessels, etc. on nerve display, improve the display effect of each nerve segment of the wrist and palm, increase readers' confidence in identifying nerves, and improve the detection of lesions. What do the findings mean? This study verified the feasibility and advantages of using contrast agents for magnetic resonance imaging of nerves in the wrist and palm. It provides a new method for clinical and imaging diagnosis of hand lesions, which can simultaneously display the morphological characteristics of nerves and lesions, reducing the difficulty of clinical diagnosis and improving the efficiency of imaging diagnosis.

A novel categorization of the muscular branches of the tibial nerve within the popliteal fossa.

BACKGROUND: The muscular branches of the tibial nerve within the popliteal fossa innervate the gastrocnemius, soleus, plantaris, and popliteus muscles. Various branching patterns have been described in textbooks; however, the underlying fundamental rules explaining the patterns remain unclear. Understanding the fundamental rule explaining the branching pattern of the innervating nerves is essential for understanding the ontogeny of skeletal muscles. Therefore, this study aimed at establishing a theory to explain the branching pattern of the muscular branches of the tibial nerve within the popliteal fossa. METHODS: The branching patterns of the muscular branches of the tibial nerve within the popliteal fossa were examined macroscopically in 62 lower limbs derived from 31 adult cadavers (22 males and 9 females, aged 49-95 years). RESULTS: The branch to the medial head of the gastrocnemius muscle invariably arose from the posteromedial side of the tibial nerve. The branches to the soleus muscle and lateral head of the gastrocnemius muscle had a common trunk in all the lower limbs and invariably arose from the posterolateral side. The branches to the plantaris and popliteus muscles arose anteriorly from the tibial nerve in this order (plantaris branch first, followed by the popliteus branch). These branches invariably arose more distally than the branch to both the heads of the gastrocnemius and soleus muscles. CONCLUSIONS: Based on these fundamental branching patterns, we suggest a novel branching categorization. The branches could be categorized into a posterior group and an anterior group, which has independent branches to the plantaris and popliteus muscles. This fundamental branching pattern and novel categorization contribute to the understanding of the ontogeny of the skeletal muscles around the flexor compartment of the leg.

Differences in the Structure and Protein Expression of Femoral Nerve Branches in Rats.

Treatment for peripheral nerve injury remains limited. The inherent differences between motor and sensory nerve fibers in peripheral nerves should be considered to improve the effects of clinical treatment of peripheral nerve injury. In this study, we investigated the differences in protein expression and ultrastructure between the cutaneous and muscular branches of the femoral nerve in rats. Our results suggest that the cutaneous branch of the femoral nerve mainly contains sensory nerve fibers and few motor nerve fibers; Correspondingly, many motor nerve fibers and few sensory nerve fibers were observed in the muscular branch of the femoral nerve, which indicate that two branches of femoral nerve are mixed nerve. The mean thickness of the myelin sheath and basement membrane of the medullated fibers in the muscular branch of the femoral nerve was greater than that of the cutaneous branch of the femoral nerve. However, the cutaneous branch has a larger G-ratio. Gene Ontology enrichment analysis revealed that the cellular component term extracellular space was the most highly enriched, and more genes were upregulated in the muscular branch of the femoral nerve. Meanwhile, the expression of key proteins were validated by Western Blot, and immunofluorescence targets the expression of key proteins, which is consistent with the enrichment analysis of Gene Ontology. In conclusion, inherent differences in protein expression and ultrastructure were observed between the cutaneous and muscular branches of the femoral nerve in rats, which should be considered in future studies on the treatment of peripheral nerve injuries.

Course pattern of the muscular branch of the median nerve in Sri Lankans hand / Curso del patrón del ramo muscular del nervio mediano de la mano en sri lankenses

Transligamentous variant of the recurrent motor branch is having a higher risk of getting damage during both endoscopic and open carpal tunnel releases. The incidence of the transligamentous variant is about 7 percent to 80 percent world wide. This wide variation of the incidence could be due to the failure of identification of the distal edge of the flexor retinaculum from the obliquely oriented fascia that runs from the distal edge. We used two criteria to identify the distal edge; the abrupt change in the thickness of the flexor retinaculum and its colour change in cross section. The incidence of transligamentous variant is rare and the reported high incidence could be due to an error in identification of the distal edge of the flexor retinaculum as shown by Kosin (1998).

Las variantes transligamentosas del ramo motor recurrente tienen un mayor riesgo de recibir daños durante la endoscopía y liberación abierta del túnel carpiano. La incidencia de la variante transligamentosa es de, aproximadamente, 7 a 80 por ciento en todo el mundo. Esta amplia variación de la incidencia podría deberse a la falla en la identificación del borde distal del retináculo flexor de la fascia de orientación oblicua que va desde el borde distal. Hemos utilizado dos criterios para identificar el borde distal, el brusco cambio en el grosor del retináculo flexor y su cambio de color en la sección transversal. La incidencia de la variante transligamentosa fue rara y el informe de la alta incidencia podría deberse a un error en la identificación del borde distal del retináculo flexor, como lo demuestra Kosin (1998).

Localization of the Motor Nerve Branches and Motor Points of the Hamstring Muscles and Triceps Surae Muscle

OBJECTIVE: To identify the precise locations of the motor branches and motor points of hamstring and triceps surae muscles to the bony landmarks. METHOD: Twenty-eight limbs of 14 adult cadavers were anatomically dissected. The adult cadavers were selected randomly without regard to gender and age. The cadravers which were unable to obtain a neutral position or which received a trauma to the posterior thighs or the lower legs were excluded from the study. The number and location of the motor branches and motor points from sciatic nerve to each hamstirng muscles and from tibial nerve to each triceps surae muscles were identified related to the bony landmarks. Bony landmarks were ischial tuberosity, medial and lateral epicondyles of femur, and medial and lateral malleolli of tibia. The length of femur was defined as the distance from the ischial tuberosity to the intercondylar line of femur and the length of lower leg was defined as the distance from the intercondylar line of femur to the intermalleolar line of tibia. The locations of the muscular branches and the motor points were expressed as the percentage of the length of femur and lower leg. RESULTS: One muscular branch from the sciatic nerve to the semimembranosus muscle and from the posterior tibial nerve to the soleus muscle, and one or two muscular branches to the biceps femoris, semitendinosus, and semimembranosus, medial gastrocnemius, lateral gastrocnemius and soleus muscle were located at 23.0+/-5.7%, 21.0+/-10.5%, 25.0+/-10.3% of the femur from the ischial tuberosity and 2.0+/-6.2%, 4.0+/-3.3% and 10.0+/-3.3% of the lower leg from the intercondylar line of femur. There were one to four motor points in the hamstring and triceps surae muscles. The motor points of biceps femoris, semitendinosus and semimembranosus were located at 33.0+/-7.8%, 28.0+/-14.5% and 48.0+/-19.0% of the femur. The motor points of the medial gastrocnemius, lateral gastrocnemius and soleus were located in 5.0+/-0.6%, 10.0+/-3.0% and 18.0+/-4.3% of the lower leg below the intercondylar line of femur. CONCLUSION: The identification of the locations of muscular branches and motor points related to the bony landmarks from this study would increase the accuracy of the motor branch blocks or motor point blocks to the hamstrings and triceps surae muscles.