Abstract: We identified nine RCTs (587 participants) for inclusion in the review, of which three studies were found at this update. The sequence generation was inadequate in one study and not described in three studies. We performed two meta-analyses to evaluate the clinical (3 trials, 261 participants) and neurophysiological (2 trials, 101 participants) outcomes of simple decompression versus decompression with submuscular or subcutaneous transposition; four trials in total examined this comparison. We found no difference between simple decompression and transposition of the ulnar nerve for both clinical improvement (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.80 to 1.08; moderate-quality evidence) and neurophysiological improvement (mean difference (in m/s) 1.47, 95% CI -0.94 to 3.87). The number of participants to clinically improve was 91 out of 131 in the simple decompression group and 97 out of 130 in the transposition group. Transposition showed a higher number of wound infections (RR 0.32, 95% CI 0.12 to 0.85; moderate-quality evidence). In one trial (47 participants), the authors compared medial epicondylectomy with anterior transposition and found no difference in clinical and neurophysiological outcomes. In one trial (48 participants), the investigators compared subcutaneous transposition with submuscular transposition and found no difference in clinical outcomes. In one trial (54 participants for 56 nerves treated), the authors found no difference between endoscopic and open decompression in improving clinical function. One trial (51 participants) assessed conservative treatment in clinically mild or moderate UNE. Based on low-quality evidence, the trial authors found that information on avoiding prolonged movements or positions was effective in improving subjective discomfort. Night splinting and nerve gliding exercises in addition to information provision did not result in further improvement. One trial (55 participants) assessed the effectiveness of corticosteroid injection and found no difference versus placebo in improving symptoms at three months' follow-up. We found only two studies of treatment of ulnar neuropathy using conservative treatment as the comparator. The available comparative treatment evidence is not sufficient to support a multiple treatment meta-analysis to identify the best treatment for idiopathic UNE on the basis of clinical, neurophysiological, and imaging characteristics. We do not know when to treat a person with this condition conservatively or surgically. Moderate-quality evidence indicates that simple decompression and decompression with transposition are equally effective in idiopathic UNE, including when the nerve impairment is severe. Decompression with transposition is associated with more deep and superficial wound infections than simple decompression, also based on moderate-quality evidence. People undergoing endoscopic surgery were more likely to have a haematoma. Evidence from one small RCT of conservative treatment showed that in mild cases, information on movements or positions to avoid may reduce subjective discomfort.

Plain-language summary: We found two randomised controlled trials (RCTs) of nonsurgical treatment. One RCT compared three groups of people with mild or moderate UNE (51 people in total). All three groups received written instructions to avoid movements or positions that provoked symptoms. The second group had the same information with elbow splints at night for three months. The third group had the same information with nerve gliding exercises. The other nonsurgical study (55 people) compared a corticosteroid injection with a sham injection. Seven RCTs compared different surgical methods: • simple decompression or transposition of the nerve (submuscular or subcutaneous transposition) (4 trials, 327 participants); • medial epicondylectomy or anterior transposition (1 trial, 47 participants); • anterior subcutaneous transposition or anterior submuscular transposition (1 trial, 48 participants); • keyhole or open surgery (1 trial, 54 participants with 56 trapped nerves). Written information alone was as effective in improving work activities and reducing pain at night as when people also used splints or did exercises. Researchers found no evidence that corticosteroid injection was effective in improving symptoms of UNE. We were able to combine results from three trials comparing two surgical techniques: simple decompression and transposition of the ulnar nerve (subcutaneous or submuscular). We found no important difference in symptom scores between the techniques at 6 to 12 months. Decompression with transposition may result in more deep and superficial wound infections. Trialists found no clinical differences between surgical techniques in the other surgical trials. People undergoing endoscopic surgery were more likely to have a haematoma (an abnormal collection of blood) after surgery. Evidence was insufficient for us to choose the best treatment for UNE. However, we did find that in mild cases, information on movements and positions to avoid may reduce discomfort. Moreover, the combined results from three surgical trials provided moderate-quality evidence that simple decompression surgery and decompression with transposition may be equally effective, but that decompression with transposition may result in more deep and superficial wound infections. The evidence is up to date to 31 May 2016.