Neurologic and histologic outcome after intraneural injections of lidocaine in canine sciatic nerves

Abstract

The data in our canine model of intraneural injection suggest that intraneural injections do not always lead to nerve injury. High injection pressures during intraneural injection may be indicative of intrafascicular injection and may predict the development of neurologic injury.

Histological confirmation of needle tip position during ultrasound-guided interscalene block: a randomized comparison between the intraplexus and the periplexus approach

“…[8][9][10]22 Despite our best efforts to avoid the hypoechoic roots using a standard approach under ultrasound guidance, it is alarming that two subperineurial (intrafascicular) injections occurred with the intraplexus technique. There are two explanations why this may have occurred: 1) operator difficulty to view the needle tip at all times and 2) the limitations of ultrasound or the operator to visualize all anisotropic fascicles and nerve layers within the interscalene groove.…”

“…1,2 This may be due to the limitation of conventional ultrasound to distinguish muscle fascia from epineurium and small fascicles, [3][4][5] such that mechanical nerve injury, barotrauma, or local anesthetic toxicity may result from unintended injection into critical nerve structures. 1,[6][7][8][9][10] This has recently led investigators to focus on how best to avoid nerves while still achieving a reliable block. No difference in block quality or onset time occurred when comparing a periplexus with an intraplexus technique for brachial plexus block at the interscalene groove.…”

Incidence of unintentional intraneural injection and postoperative neurological complications with ultrasound‐guided interscalene and supraclavicular nerve blocks*

“…Our protocol required needle adjustment for difficult injection suggestive of high pressure and previous animal studies suggest avoidance of high intraneural injection pressures may be important for prevention of nerve injury. In dogs, direct intraneural injection of 4 ml of local anaesthetic solution resulted in neurological deficits only if high pressures (> 25 psi; 172 kPa) suggestive of intrafascicular injection occurred [19,20]. In pigs, direct intraneural injection of up to 20 ml local anaesthetic solution with low injection pressures (< 10 psi; 69 kPa) resulted in ultrasound and histological markers for nerve expansion and inflammation, but did not result in functional neurological deficits at 1, 2 and 7 days post-injection [25].…”

The feasibility of micro‐ultrasound as a tool to image peripheral nerves

“…Histology studies of intraneural injection have shown that needle tips are more likely to lie within stromal tissue [5,6], On the contrary, intraneural injection studies in animal models have shown a decrement in nerve electrophysiological function [10], and nerve inflammation and haematoma associated with forceful needle-nerve contact [8,9].…”

“…Even so, intraneural injection does not necessarily result in nerve damage in patients [5,6]. Needle tips are more likely to lie within stromal tissue and local anaesthetic spreads between fascicles [7].…”