To the Editor,
Paravertebral blockade (PVB), when used as the sole anesthetic technique, provides effective anesthesia for breast surgery.1 During the COVID-19 pandemic, we shifted anesthetic techniques at our centre to exclusively use PVB on patients undergoing breast surgery. We found that PVB contributed to shorter lengths of hospital stay, significant reductions in postoperative nausea and vomiting, and a significant increase in operating room (OR) efficiency and patient satisfaction compared with our prepandemic practices.2 Since mastectomy confers frequent postoperative chronic pain with an incidence as high as 20–40%,3 we wanted to explore if PVB was associated with reduced incidence of chronic pain in our cohort of patients.
At our centre for a one-sided mastectomy under PVB, we usually administer 20–30 mL of ropivacaine 0.5% separated into several injections at 3 to 5 levels. T2–4 levels are usually blocked for all patients, and T1 is blocked if there is an intervention at the axillary level. T5 can be blocked depending on the type and extent of the surgery.
After obtaining approval from the CIUSSS de l'Est-de-l'Île-de-Montréal Research Ethics Board (Montreal, QC, Canada), we administered the French version of the neuropathic pain DN4 questionnaire via telephone to 179 of the 210 patients included in our previous study. We administered the questionnaire 20–22 months after surgery, which is fairly uncommon in the literature and gives more perspective on postoperative chronic pain.4 The DN4 questionnaire is a validated, simple, and widely used scale. A score of 4 or higher is usually considered the cut-off value for a positive neuropathic pain diagnosis. Chronic pain was defined as scoring a minimum of one item positively on the DN4 scale and a neuropathic pain score of ≥ 4.
We separated the 179 patients into three groups: general anesthesia (GA) only (n = 70), GA with fascial plane block (n = 53), and PVB (n = 56). In our previous study, all included patients had similar characteristics and demographic data.2 The fascial plane blocks completed under GA included mostly pectoralis (Pecs) II nerve blocks (one patient had a serratus anterior plane block and one an erector spinae plane block). In the GA only group, the incidence of chronic pain was 17% (12/70) and the incidence of neuropathic pain 13% (9/70). The incidences of chronic and neuropathic pain in the other groups were GA with plane block, 19% (10/53) and 8% (4/53), respectively, and PVB, 25% (14/56) and 11% (6/56), respectively. We did not find statistically significant differences in the incidences of chronic or neuropathic pain between groups (Table).
Table.
Postoperative DN4 questionnaire
| GA only group | GA with fascial plane block group | PVB only group | P value | |
|---|---|---|---|---|
| Incidence of chronic pain at 20–22 months (DN4 ≥ 1) | 12/70 (17%) | 10/53 (19%) | 14/56 (25%) | 0.53a |
| Incidence of neuropathic pain at 20–22 months (DN4 ≥ 4) | 9/70 (13%) | 4/53 (8%) | 6/56 (11%) | 0.64a |
All numbers are presented as n/total N (%)
aChi square test
DN4 = The questionnaire of neuropathic pain in 4 points; GA = general anesthesia; NRS = numeric pain rating scale, PVB = paravertebral block
In our exploratory study, we found no evidence that the use of PVB prevented neuropathic pain when compared with fascial plane blocks or no blocks at all (GA). Conflicting results remain in the literature regarding different strategies to prevent chronic pain after oncologic breast surgery.3,5 The strengths of this exploratory retrospective study are the homogeneous population, the clearly defined intervention groups, and the prolonged timing of the postoperative chronic pain questionnaire. Our present analysis did not find an association between regional anesthesia and the prevention of chronic neuropathic pain after breast surgery, but it was not powered to answer such a major and complex question. As this was a retrospective study, the lack of control for confounding factors also was a major limitation. At this point, we can conclude that the difficult initial question remains unanswered. Specific randomized control trials are needed to evaluate the true impact of regional anesthesia on chronic and neuropathic pain development after breast surgery to control for factors, including type of surgery, pre-existing chronic pain risk factors, appropriate dosage of medication or local anesthetics in blocks, and multidimensional assessment of pain.
Acknowledgements
Thanks to Nadia Godin, RN, Research Coordinator and Kathy Lessard, RN, for their help in research organization. Thanks to Kyle Vaughn Roerick, MA, Editor, for his English language edition of this manuscript.
Disclosures
Ariane Clairoux, Maxim Soucy-Proulx, and Moulay Idrissi declare no conflict of interest. Philippe Richebé received honorarium as a consultant and to give lectures from the following companies: Medasense, Abbvie, Medtronic-Covidien, Biosyent, Merck.
Funding statement
This study was fully supported by the Department of Anesthesiology and Pain Medicine of Maisonneuve-Rosemont Hospital, CIUSSS de l’Estde l’Ile de Montréal, University of Montreal.
Editorial responsibility
This submission was handled by Dr. Vishal Uppal, Associate Editor, Canadian Journal of Anesthesia/Journal canadien d’anesthésie.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
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