Comments on the article “Selective nerve root blocks vs. caudal epidural injection for single level prolapsed lumbar intervertebral disc – A prospective randomized study”

Abstract

We have read the article by Singh et al. entitled “Selective nerve root blocks vs. caudal epidural injection for single level prolapsed lumbar intervertebral disc – A prospective randomized study” published in the Journal of Clinical Orthopaedics and trauma. 8 (2),142–146 with great interest.1Singh S. Kumar S. Chahal G. Verma R. Selective nerve root blocks vs. caudal epidural injection for single level prolapsed lumbar intervertebral disc – a prospective randomized study.J. Clin. Orthop. Trauma. 2017; 8: 142-147Abstract Full Text Full Text PDF Scopus (10) Google Scholar In this article the authors have compared between selective nerve root block (SNRB) and caudal epidural injection in single level prolapsed intervertebral disc herniation. We would like to congratulate the authors for putting forward a good research in this field. We have some concerns regarding the methodology used in the article. It is a randomized control trial comparing the pain relief in patients with single level disc herniation, using steroid injection administered either by transforaminal route or by caudal route. In the SNRB group the patients receive 80 mg methyl prednisolone as a single injection, but for the patients in the Caudal epidural group patients receive three doses of 80 mg methylprednisolone each at weekly intervals irrespective of the pain relief. Naturally as this study is using steroid as a treatment for disc herniation, the amount of steroid injected in each group should also be similar. This creates a bias between the patient groups, as one group receives 80 mg of steroid and the other group receives 240mg of steroid. This can be compared with other study in which they have used the same amount of steroid in both the groups.2Ploumis A. Christodoulou P. Wood K.B. Varvarousis D. Sarni J.L. Beris A. Caudal vs transforaminal epidural steroid injections as short-term (6 Months) pain relief in lumbar spinal stenosis patients with sciatica.Pain Med. 2014; 15: 379-385Google Scholar There is also a confusion in the follow up protocol. The first follow up in both the groups is at 4 weeks after the first injection. We find that in the patients of SNRB group the time gap between the last injection and first follow up is four weeks. But in the patients of caudal epidural group the time gap is only one week as they would have received the last dose of steroid on the third week i.e only a week before the first follow up. Hence the patients of the caudal epidural group would naturally have lesser pain compared to the SNRB group at the first follow up. Another problem is regarding the definition of positive response. According the authors a decrease in the pain scores by a 50% or more and a 40% reduction of Oswestry disability index (ODI) within three weeks of the procedure, is considered as a positive response. But the patients do not have a followup visit at three weeks and the earliest follow up is at four weeks. It is also not specified whether the positive response should be assessed at 3 weeks after the last dose of caudal epidural. Because the third dose of caudal epidural is given at the third week only. The third concern is regarding the conclusion. The authors have concluded that caudal epidural injection has better short term, mid term and long term pain relieving effects compared to the SNRB group. Our careful analysis of the article revealed that the authors have not made an intergroup comparison at all. We find three tables in the article. One provides the epidemiological details, and the other two tables show the improvements in VAS scores and ODI scores of each individual group. The authors have not made an attempt to make an intergroup comparison. In order to prove superiority of one technique over the other it is always essential to perform an intergroup comparison between the variables. The authors have also suggested that caudal injection technique is easier that the selective nerve root block (SNRB). We consider that it is an individual preference and depends upon the training and skills one possesses. In conclusion we would like to say that it is a well designed study of similar population group. It could have been made better with properly designed methodology and a good statistical analysis. The study still provides good insight in the subject and stimulates further research in this regard.