Reply to the Letter of Stroh et al. Regarding the Manuscript “Rhabdomyolysis After Bariatric Surgery by Roux-en-Y-Gastric Bypass: a Prospective Study” by Oliveira et al.

Abstract

Dear Editor, We appreciate the interest of Stroh and colleagues in our work. This letter is an additional evidence of growing interest in neuromuscular and other neurological complications of bariatric surgery (BS). A few years ago, when we became interested in this subject, it was possible to find just a few articles, especially case reports, related to this issue. Fortunately, in the last years, there are more and more prospective and review studies of neurological complications of BS [1–5]. The comments about anesthetic agents and their potential risk of inducing myopathy and rhabdomyolysis (RML) are pertinent. During our research, we were concerned about this issue: the agents used in our patients were midazolam, rocuronium, fentanyl, and isoflurane, without use of propofol. Moreover, none of our patients were in use of statin or another potential myotoxic drug. We would like to clarify that we did not affirm that RML has higher frequency in females. As a matter of fact, we stated that “In our series, gender was not a risk factor of occurrence of RML” [6]. Furthermore, we also wrote that “In the prospective study of Carvalho et al. (30), and many case reports (11, 19–28), RML has been more commonly seen in men.” Although we found a higher absolute number of females in our series (63.6%) and even in the RML group (ten females and seven males), the difference failed to reach statistical significance (p=0.61, Fischer’s test). Regarding Table 3, we apologize for the error about the gender of the patients in four studies therein mentioned (Collier et al.[7], Pasnik et al.[8], Stroh et al. [9], VillalobosTorres et al. [10]), since the correct gender was male. On the other hand, Stroh et al. made two minor mistakes in their letter since the authors were Collier et al., instead of Coller et al., and they mentioned the study by Forrestire et al. [11], a study which is not present in our Table. In Table 4, the item gender (women in%) means, as discussed in the text, the gender distribution in the studies, with no mention of RML. Regarding comorbidities, the statistical analysis comparing the group with and without RML did not show statistical significance, considering that they were found in 12 of 17 patients in the RML group and three of five patients in the group without RML (p=1.00, Fisher’s test). Although the available knowledge about mechanism of RML after BS suggests a relationship between comorbidities and RML, the lack of significant correlation in our study may result from the small number of patients because the total number of individuals with comorbidities was 15 and the number in the group without RML was only three. Finally, the statement “RML after RYGBD bariatric surgery is a common complication” is appropriate, considering its high frequency in our study. We must bear in mind, however, that our investigation was not a comparative study of types of surgery. Incidentally, RYGBP often involves many of the risk factors described by Stroh et al., such as operation time>4 h, BMI>50 Kg/m, and some comorbidities. In some prospective studies involving different types of BS, as in Mognol et al. [12] and Lagandre et al.[13], the frequency of RML was much higher in F. Cardoso : L. D. Oliveira Neurology Service, Internal Medicine Department, The Federal University of Minas Gerais, Belo Horizonte, Minas Gerias, Brazil