Ultrasound-Guided Nerve Hydrodissection for Pain Management: Rationale, Methods, Current Literature, and Theoretical Mechanisms

Abstract

Nerve hydrodissection (HD), a technique used when treating nerve entrapments, involves the injection of an anesthetic, saline, or 5% dextrose in water to separate the nerve from the surrounding tissue, fascia, or adjacent structures. Animal models suggest the potential for minimal compression to initiate and perpetuate neuropathic pain. Mechanical benefits of HD may relate to release of nervi nervorum or vasa nervorum compression. Pathologic nerves can be identified by examination or ultrasound visualization. The in-plane technique is the predominant and safest method for nerve HD. Five percent dextrose may be favored as the preferred injectate based on preliminary comparative-injectate literature, but additional research is critical. Literature-based hypotheses for a direct ameliorative effect of dextrose HD on neuropathic pain are presented.

Keywords: nerve hydrodissection; neuropathic pain; pain management; ultrasonography.

Conflict of interest statement

Some of the materials and pictures contained in this manuscript have been used in previous presentations during international academic conferences. The most recent one was the Annual Conference of the Australian Association of Musculoskeletal Medicine on 24–27 October 2019 in Brisbane, Australia. The previous one was the International Symposium of Ultrasound for Regional Anesthesia and Pain Medicine (ISURA 2019) on 9–11 May 2019 in Porto, Portugal. The authors report no conflicts of interest in this work.

© 2020 Lam et al.

Figures

Figure 1

Illustration of the “nervi nervorum” and “vasa nervorum” outside the epineurium.

Figure 2

Illustration of two examples of abnormal nerves. The nerve on the left side has part of the nerve with the whole cross-sectional area (CSA) double, or even more, than normal, but the fascicles of the nerve are relatively normal. The nerve on the right side shows the CSA of the nerve is normal or slightly enlarged but one or more of the fascicles inside the nerve is much larger. The needles in this illustration will be referred to later to illustrate how method 1 can be used to hydrodissect two parallel nerves (such as tibial and fibular nerves at popliteal fossae).

Figure 3

A normal left common fibular nerve (CFN) with a cross-sectional area (CSA) at the upper limits of normal (11 mm2) at fibular head (A and B)., 3a is the original ultrasound image, (B) Shows the highlighted CSA of the normal left CFN and the color shadings with labels for sonoanatomy, Image is courtesy of 3D4Medical’s Essential Anatomy 5 app. Abbreviations: BF, biceps femoris; Gastroc, gastrocnemius; LSCN, lateral sural cutaneous nerve; PA, popliteal artery; SN, sural nerve; TN, tibial nerve.

Figure 4

An abnormal right common fibular nerve (CFN) with twice the normal CSA (22 mm2) at the fibular head (A, B) of the same patient in Figure 3., 4a is the original ultrasound image. The (B) shows the CSA of the abnormal right CFN and the color shadings with labels for sonoanatomy, Image is courtesy of 3D4Medical’s Essential Anatomy 5 app. Abbreviations: BF, biceps femoris; Gastroc, gastrocnemius; LSCN, lateral sural cutaneous nerve; PA, popliteal artery; SN, sural nerve; TN, tibial nerve.

Figure 5

(A) Shows a normal common fibular nerve (CFN) at fibular head of Figure 3 with normal fascicles, the most prominent fascicle at the upper limit of normal (1 mm2) in cross-sectional area. The color shading in (B) with labeling are for illustration purpose. Image is courtesy of 3D4Medical’s Essential Anatomy 5 app Abbreviations: BF, biceps femoris; Gastroc, gastrocnemius; LSCN, lateral sural cutaneous nerve.

Figure 6

(A) Illustrates a swollen common fibular nerve (CFN) at fibular head of Figure 4 with a swollen nerve fascicle with a cross-sectional area of 3 mm2. The color shading in (B) with labeling are for illustration purpose. Image is courtesy of 3D4Medical’s Essential Anatomy 5 app Abbreviations: BF, biceps femoris; Gastroc, gastrocnemius; LSCN, lateral sural cutaneous nerve.

Figure 7

Needle position for method 1 of hydrodissection (HD) of nerves. With the “in-plane” technique, first, the inferior surface of the nerve is hydrodissected with the needle bevel positioned up; and thereafter, the superior surface of the nerve is hydrodissected with the needle bevel positioned down.

Figure 8

Effect of bevel position on the direction of tracking of the needle. (A) Effects of bevel position up and (B) effects of bevel position down.

Figure 9

Sequence of hydrodissection (HD) of the diseased nerve using method 1. First, HD is initiated from the site where the nerve is most severely damaged or trapped, thereafter, using the same needle entry point, pivot the probe and the needle to the more proximal and/or distal part of the nerve and repeat the HD.

Figure 10

Relative direction and movement of the needle when using method 2 for hydrodissection (HD) of nerves. This shows the initial out-of-plane portion of method 2 with HD of the nerve on either side until injectate is seen surrounding the nerve, at which point the probe position is changed to in-plane with the nerve to HD the space above the nerve.