Analysis of human acellular nerve allograft combined with contralateral C7 nerve root transfer for restoration of shoulder abduction and elbow flexion in brachial plexus injury: a mean 4-year follow-up

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OBJECTIVE

Human acellular nerve allograft applications have increased in clinical practice, but no studies have quantified their influence on reconstruction outcomes for high-level, greater, and mixed nerves, especially the brachial plexus. The authors investigated the functional outcomes of human acellular nerve allograft reconstruction for nerve gaps in patients with brachial plexus injury (BPI) undergoing contralateral C7 (CC7) nerve root transfer to innervate the upper trunk, and they determined the independent predictors of recovery in shoulder abduction and elbow flexion.

METHODS

Forty-five patients with partial or total BPI were eligible for this retrospective study after CC7 nerve root transfer to the upper trunk using human acellular nerve allografts. Deltoid and biceps muscle strength, degree of shoulder abduction and elbow flexion, Semmes-Weinstein monofilament test, and static two-point discrimination (S2PD) were examined according to the modified British Medical Research Council (mBMRC) scoring system, and disabilities of the arm, shoulder, and hand (DASH) were scored to establish the function of the affected upper limb. Meaningful recovery was defined as grades of M3–M5 or S3–S4 based on the scoring system. Subgroup analysis and univariate and multivariate logistic regression analyses were conducted to identify predictors of human acellular nerve allograft reconstruction.

RESULTS

The mean follow-up duration and the mean human acellular nerve allograft length were 48.1 ± 10.1 months and 30.9 ± 5.9 mm, respectively. Deltoid and biceps muscle strength was grade M4 or M3 in 71.1% and 60.0% of patients. Patients in the following groups achieved a higher rate of meaningful recovery in deltoid and biceps strength, as well as lower DASH scores (p < 0.01): age < 20 years and age 20–29 years; allograft lengths ≤ 30 mm; and patients in whom the interval between injury and surgery was < 90 days. The meaningful sensory recovery rate was approximately 70% in the Semmes-Weinstein monofilament test and S2PD. According to univariate and multivariate logistic regression analyses, age, interval between injury and surgery, and allograft length significantly influenced functional outcomes.

CONCLUSIONS

Human acellular nerve allografts offered safe reconstruction for 20- to 50-mm nerve gaps in procedures for CC7 nerve root transfer to repair the upper trunk after BPI. The group in which allograft lengths were ≤ 30 mm achieved better functional outcome than others, and the recommended length of allograft in this procedure was less than 30 mm. Age, interval between injury and surgery, and allograft length were independent predictors of functional outcomes after human acellular nerve allograft reconstruction.

ABBREVIATIONS BPI = brachial plexus injury; CC7 = contralateral C7; CULA = contralateral upper limb adduction; DASH = disabilities of the arm, shoulder, and hand; ECM = extracellular matrix; mBMRC = modified British Medical Research Council; PN = phrenic nerve; SSN = suprascapular nerve; S2PD = static two-point discrimination.

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Article Information

Correspondence Liqiang Gu: The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. guliqiang1963@aliyun.com.

INCLUDE WHEN CITING Published online April 26, 2019; DOI: 10.3171/2019.2.JNS182620.

L.L. and J.Y. contributed equally to this work.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

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    A 43-year-old man sustained a right C5–8 nerve root injury. The patient underwent CC7 nerve root transfer combined with human acellular nerve allograft (30-mm) reconstruction to repair the injured upper trunk through the prespinal route, with additional SSN innervation 90 days after injury. A: Preoperative view of the right upper limb, which lost the function of shoulder abduction, elbow flexion, and partial finger flexion and extension. B: Findings from MRI of the brachial plexus. The coronal image reveals that the right nerve roots of C5–6 (white arrow) were ruptured. At the C6 level, a large pseudomeningocele was observed. The coronal image also shows thickening and edema of the C7 nerve root, and the continuity of the C8 nerve root was interrupted (black arrow in the level of C7–8). C and D: The patient showed excellent right shoulder abduction and elevation at the 49-month follow-up. Deltoid muscle strength was grade M4. E: The patient had good elbow flexion independent of synchronous shoulder abduction when the contralateral shoulder was adducted at the 49-month follow-up. The biceps strength was grade M4. F: The full range of shoulder external rotation with muscle strength graded as M4. Figure is available in color online only.

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    A: Exploration of the injured brachial plexus via a routine supraclavicular incision to confirm root injury; the intraoperative photograph shows that the C5 nerve root (white arrow) was ruptured and the C6 nerve root (black arrow) was avulsed. B: The CC7 nerve root (black arrow) was identified and transected at the most distal end of the divisions, and then the length of the harvested CC7 nerve root was measured. C: The harvested CC7 nerve root was passed to the injured side (black arrow). D: Measurement of the length of the gap (black arrow) between the CC7 and C5–6 nerve roots. E: The appearance of the human acellular nerve allograft (arrow). F: Human acellular nerve allografts (black arrow) were applied to bridge the gap between the divisions of the CC7 and C5–6 nerve roots. Additional SSN (white arrow) reinnervation was undertaken simultaneously. G: A customized cast was used to hold the head in the neutral position, and the injured upper extremity was immobilized in shoulder adduction and elbow flexion (anterior view). H: The posterior view of the customized cast. Figure is available in color online only.

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    Left: Histograms showing the number of patients with muscle strength restoration in the deltoid and biceps muscles. Right: Histogram showing the results of Semmes-Weinstein (S-W) monofilament test and S2PD. CULA = contralateral upper limb adducted; CULR = contralateral upper limb relaxed; DIP = distal interphalangeal joint; PIP = proximal interphalangeal joint.

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