End-to-side neurorrhaphy in brachial plexus reconstruction

Sensorimotor Outcomes of Upper Extremity End-to-Side Nerve Transfers: A Meta-analysis

BACKGROUND

End-to-side nerve transfer (ETSNT) for treatment of peripheral nerve injuries is controversial given the myriad anatomic locations, injury types, and indications. Efficacy of ETSNT remains debated. We hypothesized differences in age, sex, transfer location, and time to surgery influence outcomes.

METHODS

We performed a search of the PubMed database for ETSNT in the upper extremity from 1988 to 2018. Age, sex, transfer location, time to surgery, donor and recipient axons, and strength and sensation outcomes as measured by Medical Research Council scale were extracted from articles. Meaningful recovery was classified as Medical Research Council Grade 3 or greater. Association between meaningful recovery and younger (<25) and older (≥25) patients, injury mechanism, sex, transfer location, donor axons, and recipient axons were calculated using a χ 2 or Fisher exact test. A logistic mixed effect model was used with time to surgery, age (categorical), transfer location, and injury type as a fixed effect, and a random paper effect was included to account for correlation among patients from the same paper.

RESULTS

One hundred fifteen patients from 11 studies were included. Neither age (continuous variable, P = 0.68) nor time to surgery ( P = 0.28) affected meaningful recovery. Injury mechanism, sex, and younger age (<25 vs ≥25 years) were not associated with meaningful recovery. Within the brachial plexus ETSNT demonstrated median M4 ± 1 postoperative strength, with trunks/cords as the primary axon donor ( P = 0.03). The musculocutaneous nerve demonstrated promising but variable results in 31 patients with median strength M3 ± 4. Digital nerves consistently demonstrated meaningful sensory recovery as both donor and recipient axons (15 of 15, 100%). Logistic regression analysis demonstrated that odds of meaningful recovery after ETSNT are significantly greater for transfers within the brachial plexus compared with the distal arm (odds ratio, 41.9; 95% CI, 1.1-1586.7, P = 0.04), but location does not significantly affect meaningful recovery ( P = 0.22).

CONCLUSIONS

Patients undergoing ETSNT for digital nerve injury demonstrated meaningful recovery. End-to-side nerve transfer seems to be more efficacious when performed within the brachial plexus. This study did not find sex, injury mechanism, or time to surgery to significantly affect meaningful recovery. Additional study is needed to better evaluate the effectiveness of ETSNT in the upper extremity.

Lower subscapular nerve transfer for axillary nerve repair in upper brachial plexus palsy

BACKGROUND

The potential to utilize the lower subscapular nerve for brachial plexus surgery has been suggested in many anatomical studies. However, we know of no studies in the literature describing the use of the lower subscapular nerve for axillary nerve reconstruction to date. This study aimed to examine the effectiveness of this nerve transfer in patients with upper brachial plexus palsy.

METHODS

Of 1340 nerve reconstructions in 568 patients with brachial plexus injury performed by the senior author (P.H.), a subset of 18 patients underwent axillary nerve reconstruction using the lower subscapular nerve and constitutes the patient group for this study. The median age was 48 years, and the median time between trauma and surgery was 6 months. A concomitant radial nerve injury was found in 8 patients.

RESULTS

Thirteen patients completed a minimum follow-up period of 24 months. Successful deltoid recovery was defined as (1) muscle strength MRC grade ≥ 3, (2) electromyographic signs of reinnervation, and (3) increase in deltoid muscle mass. Axillary nerve reconstruction was successful in 9 of 13 patients, which represents a success rate of 69.2%. No significant postoperative weakness of shoulder internal rotation or adduction was observed after transecting the lower subscapular nerve.

CONCLUSIONS

The lower subscapular nerve can be used as a safe and effective neurotization tool for upper brachial plexus injury, having a success rate of 69.2% for axillary nerve repair. Our technique presents a suitable alternative for patients with concomitant radial nerve injury.

The Surgical Management of Nerve Gaps: Present and Future

Peripheral nerve injuries can result in significant morbidity, including motor and/or sensory loss, which can affect significantly the life of the patient. Nowadays, the gold standard for the treatment of nerve section is end-to-end neurorrhaphy. Unfortunately, in some cases, there is segmental loss of the nerve trunk. Nerve mobilization allows primary repair of the sectioned nerve by end-to-end neurorrhaphy if the gap is less than 1 cm. When the nerve gap exceeds 1 cm, autologous nerve grafting is the gold standard of treatment. To overcome the limited availability and the donor site morbidity, other techniques have been used: vascularized nerve grafts, cellular and acellular allografts, nerve conduits, nerve transfers, and end-to-side neurorrhaphy. The purpose of this review is to present an overview of the literature on the applications of these techniques in peripheral nerve repair. Furthermore, preoperative evaluation, timing of repair, and future perspectives are also discussed.

Plasticity of Unmyelinated Fibers in a Side-to-end Tubulization Model

BACKGROUND

Histomorphometric studies of unmyelinated fibers of the rat fibular nerves are uncommon, and side-to-end neurorrhaphy studies using the fibular nerve investigate primarily motor fibers. We investigated side-to-end tubulization (SET) technique, in which occurs collateral sprouting from the intact donor nerve fibers to the distal stump of receptor nerve, with muscle reinnervation and functional rehabilitation, to assess whether there is a successful growth of unmyelinated fibers in this model.

METHODS

Adult Wistar rats fibular nerves were sectioned to create a 5-mm gap. A 6-mm silicone tube was attached between a side of the intact tibial nerve and the sectioned fibular nerve distal stump (SET group), with the left fibular nerve as normal (sham group). Seventy days postsurgery, unmyelinated fibers from the distal segment of the fibular nerve were quantified using light and transmission electron microscopy and their diameters were measured.

RESULTS

The number of unmyelinated fibers was similar between sham (1,882 ± 270.9) and SET (2,012 ± 1,060.8), but axons density was significantly greater in the SET (18,733.3 ± 5,668.6) than sham (13,935.0 ± 1,875.8). Additionally, the axonal diameters differed significantly between groups with mean measures in sham (0.968 ± 0.10) > SET (0.648 ± 0.08).

CONCLUSIONS

Unmyelinated fiber growth occurred even with a 5-mm distance between the donor and receptor nerves, reaching similar axonal number to the normal nerve, demonstrating that the SET is a reliable technique that can promote a remarkable plasticity of unmyelinated axons.

Axonal supercharged interpositional jump-graft with a hybrid artificial nerve conduit containing adipose-derived stem cells in facial nerve paresis rat model

PURPOSE

Interpositional jump-graft (IPJG) technique with the hypoglossal nerve for supercharging can be applied in a facial nerve paresis case. In IPJG, an autologous nerve is required, and the donor site morbidity is unavoidable. Biodegradable nerve conduits are made from polyglycolic acid (PGA) and used recently without donor site complications after providing autologous grafts. Hybrid artificial nerve conduits with adipose-derived stem cells (ASCs) also attract attention as a nerve-regeneration enhancing agent. This study examined the effect of hybrid artificial nerve conduit on IPJG.

MATERIALS AND METHODS

A total of 34 Lewis rats were used and divided into 4 groups by the bridge materials: autograft (n = 8), PGA nerve conduit (n = 8), hybrid PGA nerve conduit with ASCs (n = 8), and the nontreated control groups (n = 8). ASCs were collected from 2 rats and cultured. The animals were assessed physiologically and histopathologically at 13 weeks after surgery.

RESULTS

In compound muscle action potential, the amplitude of hybrid PGA group (3,222 ± 1,779 μV) was significantly higher than that of PGA group (1,961 ± 445 μV, P < .05), and no significant difference between hybrid PGA and autograft group. All treated groups showed a myelinated nerve regeneration with double innervation in hypoglossal and facial nerve nuclei for vibrissal muscle.

CONCLUSION

This study showed the effectiveness of IPJG with a hybrid PGA conduit especially in physiological examination.

End-to-side neurotization with the phrenic nerve in restoring the function of toe extension: an experimental study in a rat model

The phrenic nerve being transferred to the posterior division of the lower trunk with end-to-end neurorrhaphy is reported to be effective in restoring the function of digit extension in literature. However, the phrenic nerve is extremely important in respiration. We designed an animal experiment to discover whether the phrenic nerve being transferred to the posterior division of the lower trunk with end-to-side neurotization was feasible and provided the theoretical basis. A sum of 36 Sprague-Dawley rats was randomly assigned to one of two groups. In Group A, the phrenic nerve was transferred to the posterior division of the lower trunk with end-to-side neurotization. In Group B, the posterior division of the lower trunk was directly sutured. The results of behavioral assessment, electrophysiology, histology and nerve fiber count and muscle weight at 12 weeks postoperatively were recorded. In Group A, none of the rats experienced tachypnea. The motion of slight toe extension was observed. The results of electrophysiology, histology and nerve fiber count and muscle weight in Group A were not as well as those of Group B, but gradually improved with time. The phrenic nerve being transferred to the posterior division of lower trunk with end-to-side neurotization can partially restore the function of toe extension in a rat model. Whether the function of digit extension can be restored by the phrenic nerve with end-to-side neurotization in humans still needs more practice in clinic.

Stimulation of morphofunctional repair of the facial nerve with photobiomodulation, using the end-to-side technique or a new heterologous fibrin sealant

This research evaluated the influence of Photobiomodulation Therapy (PBMT) on lesions of the facial nerve repaired with the end-to-side technique or coaptation with a new heterologous fibrin sealant. Thirty-two Wistar rats were separated into 5 groups: Control group (CG), where the buccal branch of the facial nerve was collected; Experimental Suture Group (ESG) and Experimental Fibrin Group (EFG), in which the buccal branch was end-to-side sutured to the zygomatic branch on the right side of the face or coaptated with fibrin sealant on the left side; Experimental Suture Laser Group (ESLG) and Experimental Fibrin Laser Group (EFLG), in which the same procedures were performed as the ESG and EFG, associated with PBMT (wavelength of 830nm, energy density 6.2J/cm², power output 30mW, beam area of 0.116cm², power density 0.26W/cm², total energy per session 2.16J, cumulative dose of 34.56J). The laser was applied for 24s/site at 3 points on the skin's surface, for a total application time of 72s, performed immediately after surgery and 3 times a week for 5weeks. A statistically significant difference was observed in the fiber nerve area between the EFG and EFLG (57.49±3.13 and 62.52±3.56μm², respectively). For the area of the axon, fiber diameter, axon diameter, myelin sheath area and myelin sheath thickness no statistically significant differences were found (p<0.05). The functional recovery of whisker movement occurred faster in the ESLG and EFLG, which were associated with PBMT, with results closer to the CG. Therefore, PBMT accelerated morphological and functional nerve repair in both techniques.

Preserved cutaneous silent period in cervical root avulsion

OBJECTIVE

Brachial plexus injuries are usually severe and involve the entire brachial plexus, sometimes occurring with root avulsions. Imaging and electrodiagnostic studies are an essential part of the lesion evaluation; however, the results sometimes show a discrepancy. The cutaneous silent period (SP) is a spinal inhibitory reflex mediated by small-diameter A-delta nociceptive fibers. The aim of the study was to determine if cutaneous SP testing may serve as a useful aid in evaluation of brachial plexus injury and/or in the diagnosis of root avulsion.

METHODS

In 19 patients with traumatic brachial plexus injury (15 males, age 18-62 years) we performed a clinical examination, CT myelography and neurophysiological testing. A needle EMG was obtained from muscles supplied by C5-T1 myotomes. Cutaneous SP was recorded after painful stimuli were delivered to the thumb (C6 dermatome), middle (C7) and little (C8) fingers while subjects maintained voluntary contraction of intrinsic hand muscles.

RESULTS

Electrodiagnostic and imaging studies confirmed root avulsion (partial or total) maximally involving C5, C6 roots in 12 patients, whereas only in 4 of them the cutaneous SP was partially absent. In the remaining subjects, the cutaneous SP was preserved.

CONCLUSION

In brachial plexopathy even with plurisegmental root avulsion, the cutaneous SP was mostly preserved. This method cannot be recommended as a reliable test for diagnosis of single root avulsion; however, it can provide a quick physiological confirmation of functional afferent A-delta fibers through damaged roots and/or trunks. The clinicians may add this test to the diagnosis of spinal cord dysfunction.

Outcome following phrenic nerve transfer to musculocutaneous nerve in patients with traumatic brachial palsy: a qualitative systematic review

BACKGROUND

The phrenic nerve can be transferred to the musculocutaneous nerve in patients with traumatic brachial plexus palsy in order to recover biceps strength, but the results are controversial. There is also a concern about pulmonary function after phrenic nerve transection. In this paper, we performed a qualitative systematic review, evaluating outcomes after this procedure.

METHOD

A systematic review of published studies was undertaken in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Data were extracted from the selected papers and related to: publication, study design, outcome (biceps strength in accordance with BMRC and pulmonary function) and population. Study quality was assessed using the "strengthening the reporting of observational studies in epidemiology" (STROBE) standard or the CONSORT checklist, depending on the study design.

RESULTS

Seven studies were selected for this systematic review after applying inclusion and exclusion criteria. One hundred twenty-four patients completed follow-up, and most of them were graded M3 or M4 (70.1 %) for biceps strength at the final evaluation. Pulmonary function was analyzed in five studies. It was not possible to perform a statistical comparison between studies because the authors used different parameters for evaluation. Most of the patients exhibited a decrease in pulmonary function tests immediately after surgery, with recovery in the following months. Study quality was determined using STROBE in six articles, and the global score varied from 8 to 21.

CONCLUSIONS

Phrenic nerve transfer to the musculocutaneous nerve can recover biceps strength ≥M3 (BMRC) in most patients with traumatic brachial plexus injury. Early postoperative findings revealed that the development of pulmonary symptoms is rare, but it cannot be concluded that the procedure is safe because there is no study evaluating pulmonary function in old age.

Shoulder and Elbow Recovery at 2 and 11 Years Following Brachial Plexus Reconstruction

PURPOSE

To report short-term and long-term outcomes on a single patient cohort observed longitudinally after nerve reconstruction for adult brachial plexus injury.

METHODS

Eleven male patients who underwent plexus reconstruction by the same surgeon at 2 institutions presented for clinical examination 7.5 or more years after surgery (average, 11.4 years; range, 7.5-22 years). Average age at the time of operation was 35 years (range, 17-73 years). Mean delay until surgery was 5 months (range, 2-11 months). Two patients had C5 paralysis, 2 had C5-C6 paralysis, 2 had C5-C7 paralysis, and 5 had complete 5-level injuries. Outcome parameters included active range of motion (ROM) in degrees, a modified British Medical Research Council (mBMRC) scale for muscle strength, and electromyographic motor unit configuration and recruitment pattern. Differences in ROM and mBMRC between 2-year and long-term follow-up were assessed with paired-sample t tests using an alpha value of .05.

RESULTS

Average shoulder abduction and mBMRC at final follow-up were both significantly improved compared with the 2-year follow-up results (P < .05). Average elbow flexion and mBMRC increased significantly between 2 years and final follow-up (P < .05). Electromyographic results for 6 patients at final follow-up showed improved motor unit configuration in 10 of 15 muscles and improved recruitment in 3 of 15 muscles compared with 2-year electromyographic results.

CONCLUSIONS

Patients continued to gain ROM and strength in the shoulder and elbow well after 2 to 3 years after surgery, contrary to previous reports. Although the precise mechanism is unknown, we speculate that a number of factors may be involved, including terminal collateral sprouting, maturation of motor units, improvements in motor unit recruitment, additional muscle fiber hypertrophy, or an as-yet undescribed mechanism. We recommend that patients be encouraged to continue strengthening exercises well after the initial recovery period and that more comparative long-term data be collected to expand on these observations.

Results of nerve reconstructions in treatment of obstetrical brachial plexus injuries

BACKGROUND

The aim of this study was to evaluate the results achieved using various surgical techniques in patients with partial and total obstetrical brachial plexus palsy.

METHODS

From 2000 to 2013, 33 patients with obstetrical brachial plexus injury underwent surgery. Twenty had follow-up periods greater than 24 months and met the criteria for inclusion in the study. All patients were evaluated using the Active Movement Scale.

RESULTS

The outcomes of different nerve reconstructive procedures including nerve transfers, nerve grafting after neuroma resection and end-to-side neurorrhaphy are presented. The overall success rate in upper plexus birth injury was 80 % in shoulder abduction, 50 % in external rotation and 81.8 % in elbow flexion with median follow-ups of 36 months. Success rate in complete paralysis was 87 % in finger and thumb flexion, 87 % in shoulder abduction and 75 % in elbow flexion; the median follow-up was 46 months. Useful reanimation of the hand was obtained in both patients who underwent end-to-side neurotization.

CONCLUSION

Improved function can be obtained in infants with obstetrical brachial plexus injury with early surgical reconstruction.

Clinical applications of end-to-side neurorrhaphy: an update

End-to-side neurorrhaphy constitutes an interesting option to regain nerve function after damage in selected cases, in which conventional techniques are not feasible. In the last twenty years, many experimental and clinical studies have been conducted in order to understand the biological mechanisms and to test the effectiveness of this technique, with contrasting results. In this updated review, we consider the state of the art about end-to-side coaptation, focusing on all the current clinical applications, such as sensory and mixed nerve repair, treatment of facial palsy, and brachial plexus injuries and painful neuromas management.