Ulnar nerve decompression and transposition with versus without supercharged end-to-side motor nerve transfer for advanced cubital tunnel syndrome: a randomized comparison study

Abstract

OBJECTIVE The objective of this prospective randomized study was to compare ulnar nerve decompression and anterior subfascial transposition with versus without supercharged end-to-side anterior interosseous nerve–to–ulnar motor nerve transfer for advanced cubital tunnel syndrome, to describe performing the nerve transfer through a small incision, and to investigate predictive factors for poor recovery following the procedure. METHODS Between January 2013 and October 2016, 93 patients were randomly allocated to a study group (n = 45) and a control group (n = 48). Patients in the study group were treated with supercharged motor nerve transfer via a 5-cm incision following decompression and anterior subfascial transposition. Patients in the control group were treated with decompression and anterior subfascial transposition alone. Postoperative pinch strength and compound muscle action potential amplitude (CMAPa) were assessed. Function of the limb was assessed based on the Gabel/Amadio scale. Between-group data were compared, and significance was set at p < 0.05. Potential risk factors were collected from demographic data and disease severity indicators. RESULTS At the final follow-up at 2 years, the results of the study group were superior to those of the control group with regard to postoperative pinch strength (75.13% ± 7.65% vs 62.11% ± 6.97%, p < 0.05); CMAPa of the first dorsal interossei (17.17 ± 5.84 mV vs 12.20 ± 4.09 mV, p < 0.01); CMAPa of abductor digiti minimi (11.57 ± 4.04 mV vs 8.43 ± 6.11 mV, p < 0.01); and excellent to good results (0.67 for the study group vs 0.35 for the control group, p < 0.05). Multivariate analysis showed that the advanced age (OR 2.98, 95% CI 2.25–4.10; p = 0.003) in the study group was related to unsatisfactory outcome in the patients. CONCLUSIONS In the treatment of advanced cubital tunnel syndrome, additional supercharged end-to-side anterior interosseous nerve–to–ulnar motor nerve transfer may produce a better function of the hand. The authors also found that cases in the elderly were related to unsatisfactory postoperative results for these patients and that they could be informed of the possibility of worsening surgery results.

Reverse End-to-Side Nerve Transfer for Severe Ulnar Nerve Injury: A Western Canadian Multicentre Prospective Nonrandomized Cohort Study

“…The comparison may not be appropriate because the outcomes of nerve graft reconstruction in high ulnar nerve injury are known to be poor and are therefore not commonly performed. To date, probably, the strongest clinical data for the potential efficacy of RETS to improve hand function are from a large prospective randomized controlled trial by Xie et al 12 However, the mean CMAP (primary outcome at the final time point) reported in the RETS group at 17.17 mV is well above that seen in healthy subjects (12.9 mV). 23 Biologically, it is difficult to reconcile this electrophysiological discrepancy.…”

“…To circumvent this, Isaacs et al 6 proposed a reverse end-to-side (RETS) transfer by coapting the end of the AIN to the side of the ulnar nerve through a perineurial window. 7 A purported advantage of RETS is that in addition to providing a route for the donor nerve fibers to grow into the ulnar nerve, it might also augment regeneration of the remaining proximal ulnar nerve fibers through the so-called “babysitting effect.” 8 There has been a growing body of literature on the RETS technique on patients with ulnar compression neuropathy, 9-13 high ulnar nerve lacerations, 14,15 and other etiologies. 16 However, the source of nerve fibers regenerating into the recipient nerve and restoration of function in RETS transfer has been inconsistent.…”

Reverse End-to-Side Transfer to Ulnar Motor Nerve: Evidence From Preclinical and Clinical Studies

“…27 It was also termed "supercharged" transfer as it supplements motor fascicles to the ulnar nerve. 28 Since then, several groups have published good to excellent results with this transfer 13,[29][30][31][32][33][34][35][36][37][38][39][40] (Tables 2 and 3). In a randomized controlled trial (RCT) involving 93 subjects with advanced cubital tunnel syndrome (CuTS), the functional outcome scores, as well as the compound muscle action potential (CMAP) in ulnar intrinsics on stimulating the ulnar nerve at the wrist, were significantly higher in patients who underwent AIN RETS transfer in addition to the conventional surgery.…”

“…Dy et al 63 reported a case where PQ was replaced by fibrofatty tissue, hence the integrity of AIN could not be verified. Peripheral neuropathy (eg, diabetics), absent CMAPs in ulnar intrinsics, 29 and advanced age 34,38 are predictors of poorer outcomes. Transfers involving antagonist nerve-muscle units result in poor functional outcomes.…”

“…Both preclinical and clinical studies have shown good results with epineurial 13,[20][21][22][23]35,38,42 as well as perineurial 24,27,29,[31][32][33][34]37,39,40 windows. Although a wider connective tissue window was shown to improve donor axonal regeneration into the recipient in a classical ETS transfer, 19,59 there are no published studies that look into the role of connective tissue disruption in RETS transfers.…”