Quantitative evaluation of the echo intensity of the median nerve and flexor muscles of the forearm in the young and the elderly

Abstract

Objectives: Musculoskeletal structures often appear brighter on imaging in the elderly, which makes it difficult to accurately delineate a peripheral nerve during ultrasound-guided regional anaesthetic procedures. The echo intensity of skeletal muscles is significantly increased in the elderly. However, there are no data comparing the echo intensity of peripheral nerves in the young and the elderly, which this study was designed to evaluate. Methods: 13 healthy, young volunteers (aged ,30 years) and 11 elderly patients (aged .60 years) who were scheduled to undergo orthopaedic lower limb surgery were recruited. The settings of the ultrasound system were standardised and a high-frequency linear array transducer was used for the scan. A transverse scan of the median nerve (MN) and the flexor muscles (FMs) at the left mid-forearm was performed and three video loops of the ultrasound scan were recorded for each subject. Still images were captured from the video loops and normalised. Computer-assisted greyscale analysis was then performed on these images to determine the echo intensity of the MN and the FMs of the forearm. Results: The echo intensity of the MN and FMs of the mid-forearm was significantly increased in the elderly (p,0.005). There was also a reduction in contrast between the MN and the adjoining FM in the elderly (p50.04). Conclusion: Under the conditions of this study, the MN and the FMs in the forearm appeared significantly brighter than those in the young, and there was a loss of contrast between these structures in sonograms of the elderly.

Ultrasound-Guided Lumbar Plexus Block Using a Transverse Scan Through the Lumbar Intertransverse Space

“…Ultrasound visibility of the lumbar paravertebral structures in our patients was also rated as "average" and was poorer than what we have previously observed in young volunteers. 9 Age-related changes in musculoskeletal structures, particularly in the elderly (>60 years), can reduce the contrast between a peripheral nerve and its surrounding muscles 20 and can adversely affect the quality of ultrasound images. 21 In conclusion, we have described a technique of performing USG LPB using the PMTS-ITS ultrasound scan window in a cohort of patients with low BMI.…”

Frequency analysis of ultrasonic echo intensities of the skeletal muscle in elderly and young individuals

“…Li et al evaluated the EIs of 40×40-pixel ROIs around the forearm flexor muscles and reported that the superficial tissue EI values were significantly greater than those of deeper tissues in young subjects but that no such difference was observed in elderly subjects 19. Similarly, in this study, the RF EI value, which is located more superficially than VI EI, was significantly greater than VI EI in the young subjects but not in the elderly subjects (Figure 1; Figure 2).…”

Age‐Related Differences in the Quantitative Echo Texture of the Median Nerve

“…The sonographic examinations were performed by a single investigator (with more than 10 years of experience in sonography) using the same ultrasound system (Micro‐Maxx version 3.1; SonoSite, Inc, Bothell, WA) with no auto‐gain or compound imaging facility and a high‐frequency linear array transducer (HFL38; 13–6 MHz, 38‐mm footprint). The ultrasound system settings were standardized for every participant as previously described 1 . This process included setting the delta key in the ultrasound system to reset to factory defaults to ensure that the initial gain was the same for every participant at the start of the sonographic examination after booting the ultrasound system.…”

“…Using computer‐assisted grayscale analysis, we recently demonstrated that the echo intensity of the median nerve at the forearm is significantly increased, and there is a loss of contrast between the median nerve and the surrounding muscles, in the elderly 1 . Age‐related reductions in the number, diameter, and average density of nerve fibers 2 , 3 and an increase in connective tissue elements 4 within a peripheral nerve, particularly after the sixth decade of life, may explain these findings 1 . However, echo intensity is a global measure of the total brightness of the pixels (gray scale) in a sonogram and does not take into account its spatial distribution.…”