OBJECTIVE In this study, the authors sought to identify the relationship between breathing and elbow flexion in patients with a traumatic brachial plexus injury (TBPI) who undergo a phrenic nerve (PN) transfer to restore biceps flexion. More specifically, the authors studied whether biceps strength and the maximal range of active elbow flexion differ between full inspiration and expiration, and whether electromyography (EMG) activity in the biceps differs between forced maximum breathing during muscular rest, normal breathing during rest, and at maximal biceps contraction. All these variables were studied in a cohort with different intervals of follow-up, as the authors sought to determine if the relationship between breathing movements and elbow flexion changes over time. METHODS The British Medical Research Council muscle-strength grading system and a dynamometer were used to measure biceps strength, which was measured 1) during a maximal inspiratory effort, 2) during respiratory repose, and 3) after a maximal expiratory effort. The maximum range of elbow flexion was measured 1) after maximal inspiration, 2) during normal breathing, and 3) after maximal expiration. Postoperative EMG testing was performed 1) during normal breathing with the arm at rest, 2) during sustained maximal inspiration with the arm at rest, and 3) during maximal voluntary biceps contraction. Within-group (paired) comparisons, and both correlation and regression analyses were performed. RESULTS Twenty-one patients fit the study inclusion criteria. The mean interval from trauma to surgery was 5.5 months, and the mean duration of follow-up 2.6 years (range 10 months to 9.6 years). Mean biceps strength was 0.21 after maximal expiration versus 0.29 after maximal inspiration, a difference of 0.08 (t = 4.97, p < 0.001). Similarly, there was almost a 21° difference in maximum elbow flexion, from 88.8° after expiration to 109.5° during maximal inspiration (t = 5.05, p < 0.001). Involuntary elbow flexion movement during breathing was present in 18/21 patients (86%) and averaged almost 20°. Measuring involuntary EMG activity in the biceps during rest and contraction, there were statistically significant direct correlations between readings taken during normal and deep breathing, which were moderate (r = 0.66, p < 0.001) and extremely strong (r = 0.94, p < 0.001), respectively. Involuntary activity also differed significantly between normal and deep breathing (2.14 vs 3.14, t = 4.58, p < 0.001). The degrees of involuntary flexion were significantly greater within the first 2.6 years of follow-up than later. CONCLUSIONS These results suggest that the impact of breathing on elbow function is considerable after PN transfer for elbow function reconstruction following a TBPI, both clinically and electromyographically, but also that there may be some waning of this influence over time, perhaps secondary to brain plasticity. In the study cohort, this waning impacted elbow range of motion more than biceps muscle strength and EMG recordings.
BACKGROUND The phrenic nerve has been extensively reported to be a very powerful source of transferable axons in brachial plexus injuries. The most used technique used is supraclavicular sectioning of this nerve. More recently, video-assisted thoracoscopic techniques have been reported as a good alternative, since harvesting a longer phrenic nerve avoids the need of an interposed graft. OBJECTIVE To compare grafting vs phrenic nerve transfer via thoracoscopy with respect to mean elbow strength at final follow-up. METHODS A retrospective analysis was conducted among patients who underwent phrenic nerve transfer for elbow flexion at 2 centers from 2008 to 2017. All data analysis was performed in order to determine statistical significance among the analyzed variables. RESULTS A total of 32 patients underwent supraclavicular phrenic nerve transfer, while 28 underwent phrenic nerve transfer via video-assisted thoracoscopy. Demographic characteristics were similar in both groups. A statistically significant difference in elbow flexion strength recovery was observed, favoring the supraclavicular phrenic nerve section group against the intrathoracic group (P = .036). A moderate though nonsignificant difference was observed favoring the same group in mean elbow flexion strength. Also, statistical differences included patient age (P = .01) and earlier time from trauma to surgery (P = .069). CONCLUSION Comparing supraclavicular sectioning of the nerve vs video-assisted, intrathoracic nerve sectioning to restore elbow flexion showed that the former yielded statistically better results than the latter, in terms of the percentage of patients who achieve at least level 3 MRC strength at final follow-up. Furthermore, larger scale prospective studies assessing the long-term effects of phrenic nerve transfers remain necessary.
Background Traumatic brachial plexus injuries (BPIs) represent a major cause of disability in young patients. The purpose of this study was to compare two populations (from Argentina and Germany) who suffered a traumatic BPI after a motorcycle accident to identify predictors of BPI and brain injury severity. Methods Univariate and multivariable intergroup comparisons were conducted, and odds ratios were calculated to assess the associations between the different demographic, morphometric, and trauma-related variables, and the type and severity of patients' injuries. Pearson correlation coefficients were generated to identify statistically significant correlations. Results A total of 187 patients were analyzed, 139 from Argentina and 48 from Germany. The two countries differed significantly in age and several morphometric and trauma-related variables. The clinical presentation was also convincingly different in the two countries. The following three variables remained as statistically significant predictors of a complete (vs. partial) BPI: living in Argentina (p < 0.001), presenting prior to 2015 (p = 0.004), and greater estimated speed at the time of impact (p = 0.074). As for BPIs, a disproportionate percentage (85.6%) of more severe brain injuries occurred in Argentinian patients (p < 0.001) and among those whose accident involved striking a stationary vertical object. Conclusions This study identified several factors that might be considered when planning governmental policies and education initiatives to reduce BPI and brain injuries related to motorcycle use. Level of evidence II-2 (evidence obtained from case–control studies).
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