Intraneural ?

Intraneural ?

This letter to the editor was rejected “as firmly as possible”, we see some necessity for public access .....

Ultrasound (US) guided Regional Anesthesia (RA) needs thoroughness but not adventurous experiments

RE: Bigeleisen: Anesthesiology 2006; 105: 779-83

T.Grau; B. Moriggl

Thomas Grau MD PhD Department of Anaesthesiology, Intensive Care, Palliative Care and Pain Medicine, BG University Hospital Bergmannsheil Bochum, Bürkle de la Camp Platz 1, 44789 Bochum Germany e-mail : grau@anaesthesia.de

Bernhard Moriggl MD Prof. Department for Anatomy, Histology and Embryology Medical University Innsbruck Müllerstrasse 59 A-6020 Innsbruck

Bigeleisen conducted his study because he detected accidental puncturing and consecutive LA application into nerves in reviewing his video archives of 50 “US-guided axillary blocks”. Basically, he performed axillary nerve blocks in 26 patients with application of 2-3 ml of LA intraneural. This was followed by application of another 2-3 ml around the nerve.

Among the clinical physicians practicing and teaching US-guided procedures in RA (not only peripheral nerve blocks), there is absolutely no “debate about what images mean”! Moreover, there is no consistency between a local anesthetic ring around a nerve and a “tissue plane” (whatever this might be). We argue that such description is simply embarrassing. The same applies to what we read with complete bewilderment in the whole second paragraph of the introduction. There is an unmasking description of the approach to the peripheral nerve as practiced by the author.

There is no beating about the bush: If anesthetists doing US-guided procedures really puncture “one or more nerves” during an axillary blockade “in each patient” – presumably inadvertently! - we may well do withoutcolleagues having comparable “experience”! That patients “did not experience any known sequelae” does by no means justify performance of this study. We see no necessity to “determine the incidence of needle entry into the nerve”, and to demonstrate what a nerve looks like “if LA is injected into a nerve”. Such a processing has nothing to do with an US guided block concept.

Of course we all know that the risk of permanent nerve injury is small if one considers the thousands of blocks performed every day³. But there is still enough evidence of what may happen to nerves if the injection of the local anaesthesia is applied intraneural⁴. Done intentionallyin patients, to our opinion only one injured nerve is too much. It is no matter if there is really “institutional review board approval “and – hard to believe – “written patient consent”!

This leads us to the “Materials and Methods section” where the attentive reader gets clear evidence of other severe problems. The statement “If neither an intraneural injection nor a halo appeared, the process was repeated one more time….” Must be interpreted as follows: the author was either unable to locate nerves properly and detect small amounts of LA in order to improve needling and further LA application or, to the worst, simply could not make the spot of injection and the scanning plane congruent! This clearly shows the author’s shortcomings.

Under those circumstances and with such technical underperformance, one can not seriously conduct a study as claimed. There is also no usable description of the puncture and the depiction procedures.

Additional comments: Apart from what has been stated above, there are several descriptions and/or documentations within the paper that would need explanation or clarification.

Figure 2a-c is not convincing as to prove statements given within the text (different appearance of halos etc.). Moreover, there is certainly no “cephalic vein” located “in the axilla” and it is unclear why the author was looking for the pectoralis major muscle in order to locate or trace the respective nerves within the axilla?! We were very astonished reading in the Results section that apart from the musculocutaneous nerve the radial nerve was the easiest to block. To our own experience, it is exactly the radial nerve that may bear some problems during an axillary block.

As far as the musculocutaneous nerve is concerned we do not really understand why puncture should be more difficult. Course and location within the coracobrachialis muscle or between the latter and the short head of biceps brachii can be demonstrated easily. The visibility is so impressively clear in almost all patients.

In addition, the author postulates that “nerves in the axilla have little or no fascia surrounding them…” First of all there is never any definition of the term “fascia” as used in this paper repeatedly (as an example see “….the nerve moves 1 – 2 cm before the needle pierces an anatomical structure that may be the fascia”) Bigeleisen may have missed that there are clear terms as far as connective tissue associated with nerves is concerned. Secondly this statement would be in contradiction to the feeling of a pop as described earlier in the study. But all this “fascial thing” remains unclearthroughout the paper so it is hard to interpret what is really meant. And finally, differentiation instead of generalization applies. If one includes e.g. the musculocutaneous nerve with the given “fascial structures”, it is simply wrong anyway. Other errors and floppy descriptions are numerous within this paper, they simply prove a lack of basic knowledge. Just as a cases in point and apart from inadequate use of the term “superior” (and “inferior” later on) we would like to stress that it is not possible to block the musculocutaneous and median nerves “using an approach superior to the axillary artery” in a plane axillary blocks are performed.

In Conclusion we are more than concerned about this article published in Anesthesiology and we can not understand why the accompanyingEditorial view is so benevolent².

Done with knowledge, experience and caution, US guided procedures in RA are of great value and benefit for patients. This has been shown in several publications from different groups in the field^5-8. It has also been demonstrated that the amount of LA can be reduced significantly^9-10 and other studies will follow. We are thus able to safely, quickly and effectively block peripheral nerves. We are “seeing what we are doing!” and we are not “debating what images mean” ^5,11,12. So there is absolutely no need for doing an “intraneural nerve block“ in patients. Instead, we should take every effort in serious education of colleagues willing to learn US guidance in Regional Anaesthesia. Further studies should concentrate on ideas that further improve this valuable technique.

References:

1. Bigeleisen PE: Nerve puncture and apparent intraneural injection during ultrasound-guided axillary block does not invariably result in neurologic injury. Anesthesiology 2006; 105: 779-83

2. Borgeat A: Regional anesthesia, intraneural injection, and nerve injury: beyond the epineurium. Anesthesiology 2006; 105: 647-8

3. Auroy Y, Benhamou D, Bargues L, Ecoffey C, Falissard B, Mercier FJ, Bouaziz H, Samii K: Major complications of regional anesthesia in France: The SOS Regional Anesthesia Hotline Service. Anesthesiology 2002; 97: 1274-80

4. Hadzic A, Dilberovic F, Shah S, Kulenovic A, Kapur E, Zaciragic A, Cosovic E, Vuckovic I, Divanovic KA, Mornjakovic Z, Thys DM, Santos AC: Combination of intraneural injection and high injection pressure leads to fascicular injury and neurologic deficits in dogs. Reg Anesth Pain Med 2004; 29: 417-23

5. Grau T: Ultrasonography in the current practice of regional anaesthesia. Best Pract Res Clin Anaesthesiol 2005; 19: 175-200

6. Gray AT: Ultrasound-guided regional anesthesia: current state of the art. Anesthesiology 2006; 104: 368-73, discussion 5A

7. Sites BD, Beach ML, Spence BC, Wiley CW, Shiffrin J, Hartman GS, Gallagher JD: Ultrasound guidance improves the success rate of a perivascular axillary plexus block. Acta Anaesthesiol Scand 2006; 50: 678-84

8. Sandhu N, Capan L: Ultrasound-guided infraclavicular brachial plexus block. Br J Anaesth 2002; 89: 254-9

9. Marhofer P, Sitzwohl C, Greher M, Kapral S: Ultrasound guidance for infraclavicular brachial plexus anaesthesia in children. Anaesthesia 2004; 59: 642-6

10. Sandhu NS, Bahniwal CS, Capan LM: Feasibility of an infraclavicular block with a reduced volume of lidocaine with sonographic guidance. J Ultrasound Med 2006; 25: 51-6

11. Retzl G, Kapral S, Greher M, Mauritz W: Ultrasonographic findings of the axillary part of the brachial plexus. Anesth Analg 2001; 92: 1271-5

12. Schwemmer U, Schleppers A, Markus C, Kredel M, Kirschner S, Roewer N: [Operative management in axillary brachial plexus blocks : Comparison of ultrasound and nerve stimulation.]. Anaesthesist 2006; 55: 451-6