Comment on "perforator-guided drug injection in the treatment of abdominal wall pain"

We have read with interest and attention the work of Weum and de Weerd about ultrasonographic-guided injection of botulin for the treatment of chronic abdominal wall pain [1]. The authors treated 15 patients administering local botulin close to abdominal cutaneous nerves, whose entrapment may be the cause of this type of chronic pain. The treatment of this condition is often surgical, but conservative approach can be considered, like local anesthetic drugs. This local injection can be blindly performed, but, as the authors illustrated, some limits could be noticed: suboptimal results due to imprecise administration, and risks of side effects like perforation of abdominal wall. The patients of the paper were treated using ultrasound (US) as guide for injection and Figure 2 Ultrasound image shows the mass(m) with irregular margins as heterogeneous and hypoechoic. Doppler imaging clearly designates the normal subclavian(arrow) and carotis(arrowhead) arteries, and jugular vein thrombosis(asterisk). Clinical figures (small images) designate the orientation of the ultrasound probe in relation to the patient; S¼subclavian artery. Coraci et al. 2438 Downloaded from https://academic.oup.com/painmedicine/article-abstract/17/12/2438/2741183 by Sapienza Università di Roma user on 31 August 2018 they showed no complications. The article is very important and informative because it presents the usefulness of this technique as support of the botulin administration. In particular, the authors used color Doppler ultrasound, with a machine equipped with a 9 MHz linear probe, to depict the exit point of perforator vessels, where cutaneous nerves are supposed to be. The authors admitted that they were not able to identify the single nerves with this approach. We agree with the authors about the use of Doppler technique, because this can reveal the position of the vessels. As the authors suggest, Doppler technique can be used to find landmarks for the peri-nerve injection, and the correct evaluation of the vessel position can avoid occurrence of side effects, for example during botulin injection. Furthermore, even the use of Power Doppler is recommendable, because it can assess the very small blood flow [2]. In general, ultrasound is a very useful tool for the diagnosis and management of neuropathies, for support to neurophysiological techniques and treatment, like the work of Weum and de Weerd shows [3]. However, US is often able to depict very small nerves, even if, probably, higher frequency probe and long training are needed [4]. In other cases, if the very small nerves are not visible, their eventual morphological abnormalities are observable. Focal nerve enlargement or the presence of a hypoechoic structure may suggest or confirm nerve involvement [5]. Therefore, the ultrasonographic assessment of chest and abdominal wall nerves, in cases of chronic pain, may reveal the real cause of the symptoms and, hence, play a crucial role for the differential diagnosis and directly indicate the best site for useful treatment