Quantitative Architecture of the Brachial Plexus and Surrounding Compartments, and Their Possible Significance for Plexus Blocks

Department of Anesthesiology, University Medical Center Utrecht, Utrecht, The Netherlands.
Anesthesiology (Impact Factor: 5.88). 03/2008; 108(2):299-304. DOI: 10.1097/01.anes.0000299433.25179.70
Source: PubMed


Nerve injury after regional anesthesia of the brachial plexus (BP) is a relatively rare and feared complication that is partly attributed to intraneural injection. However, recent studies have shown that intraneural injection does not invariably cause neural injury, which may be related to the architecture within the epineurium. A quantitative study of the neural components and the compartment outside BP was made.
From four frozen shoulders, high-resolution images of sagittal cross-sections with an interval of 0.078 mm were obtained using a cryomicrotome to maintain a relatively undisturbed anatomy. From this data set, cross-sections perpendicular to the axis of the BP were reconstructed in the interscalene, supraclavicular, midinfraclavicular, and subcoracoid regions. Surface areas of both intraepineurial and connective tissue compartments outside the BP were delineated and measured.
The nonneural tissue (stroma and connective tissue) inside and outside the BP increased from proximal to distal, being significant between interscalene/supraclavicular and midinfraclavicular/subcoracoid regions (P < 0.001 for tissue inside BP, P < 0.02 for tissue outside BP). The median amount of neural tissue remained approximately the same in the four measured regions (41.1 +/- 6.3 mm; range, 30-60 mm). The ratio of neural to nonneural tissue inside the epineurium increased from 1:1 in the interscalene/supraclavicular to 1:2 in the midinfraclavicular/subcoracoid regions.
Marked differences in neural architecture and size of surrounding adipose tissue compartments are demonstrated between proximal and distal parts of the brachial plexus. These differences may explain why some injections within the epineurium do not result in neural injury and affect onset times of BP blocks.

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Available from: G.J. Groen, Feb 03, 2014
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    • "mono-or oligofascicular pattern is found proximally whereas the multifascicular pattern is located more distally (Fig. 6C) although there are still some nerves that maintain its multifascicular pattern throughout its course. Also the relative and absolute amount of the non-neural tissue increases from proximal to distal areas (polyfascicular configuration ) (Bonnel, 1984; Sunderland, 1978; Yokoyama, 1989; Yokoyama et al., 1986; Moayeri et al., 2008; Van Geffen et al., 2009; Moayeri and Groen, 2009). Axons are not always in the same place along the nerve. "
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    ABSTRACT: The molecules deposited outside the nerve root, nerve root cuffs or nerve need to cross several structures before reaching the axons. The diffusion occurs initially through the tissue surrounding the nervous structures, then crossing and distributing among the intraneural area such as endoneurium, pia mater, arachnoid lamina, dura mater, fat tissue and transitional epithelium inside nerve root cuffs, epineurium, perineurium and endoneurium of peripheral nerve. The morphological characteristics of the tissue surrounding and protecting axons may change depending on the area and can influence the diffusion of local anesthetics to reach axons.The study of these morphological variables in depth will be of help to choose the best area of injection, according to the type of surgery and to analyze any possible complications. © 2011 European Federation of International Association for the Study of Pain Chapters.
    11/2011; 5(2):377 - 385. DOI:10.1016/j.eujps.2011.08.042
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    • "Secondly, since US imaging is performed in an intact patient for an optimal comparison also intact, so-called undisturbed, anatomy is needed. For undisturbed anatomy cryomicrotomy is considered the gold standard (Hogan, 1991, 2002; Moayeri et al., 2008). Cryomicrotome sections have been used to elucidate lumber epidural anatomy (Hogan, 1991, 2002) but this was performed with varying distances between the sections. "
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    ABSTRACT: Background: The application of ultrasound (US) in peripheral nerve blocks has increased substantially during the last 15. years. However, this technique may have some drawbacks, one of which is the need of a high level of experience of the anaesthesiologist in performing US-guided blocks, a.o. in interpreting the cross-sections displayed in the ultrasound images. Sonoanatomical cross-sections produced by digitized anatomy are easier to understand. Methods: From seven cadavers by cryomicrotomy a large series of consecutive high-resolution photographs with an interval of 0.078. mm were obtained from various regions. By multiplanar reformatting perpendicular reconstructions were made using self-developed software (E-MAC). Thus, 3-D tissue blocs were obtained with a voxel size of 78. μm that enabled the reconstruction of oblique cross-sections, in which sizes, angles and surface areas could be measured. Finally, a movie-like animation of consecutive cross-sections including a variable magnification display was built in. Results: Reconstructions from the 3-D tissue blocs illustrate important sonoanatomical issues of the brachial plexus (BP). Its proximal nerve roots show varying angulations, whereas the nerves, towards distal, exhibit a shift in internal architecture and changing topography relative to the subclavian and axillary artery. Blood vessels that may hinder needle insertion are highlighted. Conclusion: Multiplanar reformatting of digitized anatomy has made feasible the reconstructions of non-standard anatomical planes. The various (oblique) cross-sections explain the difference between hypo-echogenic vs hyper-echogenic structures of the BP-nerves, the position of the needle tip in the various BP-approaches, the topography of important blood vessels displayed in US images and illustrates why the US-probe needs a continuous change in angulation. © 2010 European Federation of International Association for the Study of Pain Chapters.
    European Journal of Pain Supplements 11/2010; 2010(4):303–311. DOI:10.1016/j.eujps.2010.09.005
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