Given the task definition and input, reply with output. Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

In this study, it was aimed to determine whether median nerve epineurectomy is beneficial in the surgical management of carpal tunnel syndrome (CTS). The study enrolled 72 patients including 34 patients without epineurectomy (Group A) and 38 patients with epineurectomy (Group B). Surgery was performed in patients with severe electrodiagnostic CTS findings, CTS duration >1 year and flattening along with hypervascularization in median nerve. All patients were assessed by visual analog scale, two-point discrimination test as well as subjective and objective findings at baseline and on the months 1, 3, and 6 after surgery. The mean age was 58.3 years (42-75 years) in 38 patients who underwent an epineurectomy, whereas it was 61.5 years (41-82 years) in 34 patients who did not have an epineurectomy. The groups were similar with regard to age, gender, duration of symptoms, and preoperative physical findings. Mean visual analog scale (VAS) scores were 1.7 in Group A and 1.8 in Group B. Again, these differences were not significant, on physical examination, the average two-point discrimination in the distribution of the median nerve was 4.9 mm (range: 3-11 mm) in Group A and 5.3 mm (range: 3-10 mm) in Group B. In postoperative evaluations, there was a better improvement in visual analog scale scores, two-point discrimination test and subjective symptoms including dysesthesia, pain and nocturnal pain within first 3 months; however, there was no marked difference in objective and subjective findings on the 6th month. No complication or recurrence was observed. We believe that median nerve epineurectomy is unnecessary in the surgical management of primary CTS since it has no influence on the midterm outcomes.

What nerve is involved in carpal tunnel syndrome?