Despite, the limitation in the number of randomized controlled trials available in current literature, this systematic review was able to provide evidence that CTS symptoms improved in both interventions.
All the studies reported that both conservative managements (splinting, steroid and laser therapy) and surgery result in clinically significant improvement in symptoms. Some authors [13, 15, 17–19] concluded that surgical decompression produces long-term systematic improvement compared with the non-surgical intervention. We found that the positive impact of conservative management plateaus within 3 months whereas, the clinical effect of surgical intervention up until 12th months after the treatment. The relative advantage of surgery at 6 months (WMD = 0.35) indicated that patient with surgical release had approximately 0.35 points lower functional scores than those receiving conservative intervention.. Although there was a similar trend at 12 months, no further improvement was observed at 12 months of follow-up. Thus, the current treatment approach of providing a conservative management as a front-line treatment in mild to moderate cases before considering surgery is justified.
However, surgery was superior to the non surgical intervention regarding the improvement of electrophysiological study. The relative advantage of surgery (RR = 2.3) indicated that approximately twice as many patients achieve better outcomes with surgery. This is important information for patient who fails conservative management to understand when deciding whether they should consent to surgery.
Prognosis was not addressed in these study trials but others have indicated that patients presenting with higher symptom severity scores and those not responding within the first six weeks are more likely to proceed to surgery following conservative management . Given that the size of the treatment advantage for surgical management is relatively small, and that improvements are noted with both conservative and surgical approaches the evidence does not support proceeding directly to surgery. The presenting symptoms/nerve damage, response/relief after conservative management, comorbid issues and patient circumstances/preferences will determine the optimal decision about surgery. There are potential complications that patients must consider, in particular for surgical management or steroid injection. Given the huge variation of how complications are defined, this systematic review was not well positioned to determine accurate rates of these complications.
Our review indicates substantial heterogeneity in effects between studies. This may have resulted from variations between the studies in terms of intervention techniques, length of treatment, methodological quality, etc. For example, all the patients in splinting group received 6 weeks treatment in Gerritsen study  while patients in Ucan study  used the splinting for 3 months. For this reason future systematic reviews that included larger numbers of studies might be useful to differentiate subgroups who would benefit most from conservative versus surgical management or factors associated with successful treatment in either treatment arm.
Critical appraisal of trials involving surgery, or hands-on interventions within the scope of conservative management have some inherent challenges in blinding that affect their scores on most critical appraisal instruments. While the Jadad scale is commonly used, others have pointed out its lack of reliability and validity with respect to surgery and rehabilitation research [24, 25]. For this reason we used a 24-item structured evaluation instrument  that has been used in other hand surgery/therapy systematic reviews [27, 28]. This instrument also provides extra credit for blinding, but has an intermediary score for cases where blinding is not possible. In addition, because it addresses a variety of aspects of study in addition to blinding there is an opportunity for well-designed surgery trials to be favorably rated despite a lack of blinding.
One limitation of this systematic review is only studies written in English were included, which might introduce a publication bias. However, one recent assessment reported that non-English papers are likely to be of low quality and could result in bias into a review .