The utility of three‐dimensional optical projection tomography in nerve injection injury imaging

Abstract

Summary The examination of nerve microarchitecture has hitherto been limited solely to two‐dimensional imaging techniques. The objective of this study was to evaluate the ability of optical projection tomography to discern the nerve microarchitecture and injection injury in three dimensions. Five piglets were studied, whose median and lingual nerves were unilaterally injected post mortem with preset volumes of local anaesthetic, excised and subsequently made transparent with benzyl alcohol benzyl benzoate. Images were captured in three dimensions. The same contralateral nerves were used as controls. Using optical projection tomography, we observed differences between the internal organisation of the median and the lingual nerves, which potentially explain the variations in their susceptibility to injury. This was demonstrated in three dimensions as a disruption to the fascicles in the lingual nerve, and their displacement in the median nerve. This new technology offers potential for studying nerve microarchitecture topography and its tolerance to injection injury.

Interfascial Plane Blocks

“…Methods used to study the microanatomy of nerves (eg, electron microscopy, optical projection tomography) may be useful. 33,34 Issues related to the spread of local anesthetic and the potential influence of neighboring organs and sidedness may be explored to some degree through human cadaver studies. Using methodology described previously, patterns of dye spread with comparisons of left-and right-sided injections within a sample of human cadavers require further investigation.…”

Fluoroscopically Guided Epidural Injections of the Cervical and Lumbar Spine

“…Although not all intraepineural (intraneural) injections lead to neurologic complications, intraepineural injections are considered a major risk factor for nerve damage (100,101). In addition, extraepineural injection is reportedly more effective than intraepineural injection in the management of lumbar radiculopathy (102).…”

Median and ulnar nerve fascicle imaging using MR microscopy and high‐resolution ultrasound

“…In conventional 3T scanners, separating fascicles is difficult even with dedicated protocol with small field of view, dedicated sequence, and surface coil 16,40,41 . In vivo studies have exploited the strength of the MRI field up to 8T and claimed good visualization of fascicles 37,42,43 . Clearer depiction of fascicles has been proven with 7T MRI machines in comparison to 3T machines; however, 7T scanners have currently limited use in a clinical setting.…”

“…Profound understanding of fascicular anatomy can only be achieved through 3-dimensional representation of fascicular relationships. 9,37 Despite HCS being a reference standard, it has some drawbacks such as enormous workload and 2-dimensional acquisition with poor image registration. 10 Superb spatial resolution of MRM allows good differentiation of even finer anatomical details such as external epineurium, perineurium, and interfascicular connective tissue.…”