Contralateral cervical seventh nerve transfer for spastic arm paralysis via a modified prespinal route: a cadaveric study

Cadaveric Feasibility Study on Modified Contralateral C7 Nerve Transfer for Targeted Recovery in Hemiplegic Arms

BACKGROUND

Contralateral cervical seventh (cC7) nerve to C7 transfer has been proven effective for treating spastic upper limb. However, for those whose major impairment is not in the C7 area, cC7 nerve transfer to other nerves may achieve a better outcome. The aim of this study was to explore the optimal surgical approach for transferring cC7 to 1 or 2 nerves in a cadaveric study, and to evaluate possible applications for patients with hemiplegia.

METHODS

Modified cC7 transfer to 1 (5 procedures) or 2 nonadjacent (3 procedures) nerve roots was proposed, and success rates of direct coaptation through 2 surgical approaches-the superficial surface of longus colli (sLC) and the deep surface of longus colli (dLC) approach-were compared. The length, diameter, and distance of relevant nerves were also measured in 25 cadavers.

RESULTS

Compared with the sLC approach, the distance of the dLC approach was 1.1 ± 0.3 cm shorter. The success rates for the sLC and dLC approaches were as follows: cC7 to C5 surgery, 94%, and reached 98%; cC7 to C6 surgery, 54% and 96%; cC7 to C7 surgery, 42% and 94%; cC7 to C8 surgery, 34% and 94%; cC7 to T1 surgery, 24% and 62%; cC7 to C5C7 surgery, 74% and 98%; cC7 to C6C8 surgery, 54% and 98%; and cC7 to C7T1 surgery, 42% and 88%.

CONCLUSIONS

The dLC approach greatly improved the direct coaptation rate for cC7 nerve transfer. The modified cC7 nerve transfer procedures are technically feasible for further application in clinic.

Peripheral nerve transfers for dysfunctions in central nervous system injuries: a systematic review

BACKGROUND

The review highlights recent advancements and innovative uses of nerve transfer surgery in treating dysfunctions caused by central nervous system (CNS) injuries, with a particular focus on spinal cord injury (SCI), stroke, traumatic brain injury, and cerebral palsy.

METHODS

A comprehensive literature search was conducted regarding nerve transfer for restoring sensorimotor functions and bladder control following injuries of spinal cord and brain, across PubMed and Web of Science from January 1920 to May 2023. Two independent reviewers undertook article selection, data extraction, and risk of bias assessment with several appraisal tools, including the Cochrane Risk of Bias Tool, the JBI Critical Appraisal Checklist, and SYRCLE's ROB tool. The study protocol has been registered and reported following PRISMA and AMSTAR guidelines.

RESULTS

Nine hundred six articles were retrieved, of which 35 studies were included (20 on SCI and 15 on brain injury), with 371 participants included in the surgery group and 192 in the control group. These articles were mostly low-risk, with methodological concerns in study types, highlighting the complexity and diversity. For SCI, the strength of target muscle increased by 3.13 of Medical Research Council grade, and the residual urine volume reduced by more than 100 ml in 15 of 20 patients. For unilateral brain injury, the Fugl-Myer motor assessment (FMA) improved 15.14-26 score in upper extremity compared to 2.35-26 in the control group. The overall reduction in Modified Ashworth score was 0.76-2 compared to 0-1 in the control group. Range of motion (ROM) increased 18.4-80° in elbow, 20.4-110° in wrist and 18.8-130° in forearm, while ROM changed -4.03°-20° in elbow, -2.08°-10° in wrist, -2.26°-20° in forearm in the control group. The improvement of FMA in lower extremity was 9 score compared to the presurgery.

CONCLUSION

Nerve transfer generally improves sensorimotor functions in paralyzed limbs and bladder control following CNS injury. The technique effectively creates a 'bypass' for signals and facilitates functional recovery by leveraging neural plasticity. It suggested a future of surgery, neurorehabilitation and robotic-assistants converge to improve outcomes for CNS.

Contralateral seventh cervical nerve transfer for central spastic arm paralysis: a systematic review and meta-analysis

Objectives

The specific benefits of a contralateral cervical 7 nerve transplant in people with spastic paralysis of the upper extremity caused by cerebral nerve injury are unclear. To evaluate the efficacy and safety of contralateral C7 nerve transfer for central spastic paralysis of the upper extremity, we conducted a comprehensive literature search and meta-analysis.

Materials and methods

PRISMA guidelines were used to search the databases for papers comparing the efficacy of contralateral cervical 7 nerve transfer vs. rehabilitation treatment from January 2010 to August 2022. The finishing indications were expressed using SMD ± mean. A meta-analysis was used to assess the recovery of motor function in the paralyzed upper extremity.

Results

The meta-analysis included three publications. One of the publications offers information about RCTs and non-RCTs. A total of 384 paralyzed patients were included, including 192 who underwent CC7 transfer and 192 who received rehabilitation. Results from all patients were combined and revealed that patients who had CC7 transfer may have regained greater motor function in the Fugl-Meyer score (SMD 3.52, 95% CI = 3.19-3.84, p < 0.00001) and had superior improvement in range of motion compared to the rehabilitation group (SMD 2.88, 95% CI = 2.47-3.29, p < 0.00001). In addition, the spasticity in the paralyzed upper extremity significantly improved in patients with CC7 transfer (SMD -1.42, 95% CI = -1.60 to -1.25, p < 0.00001).

Conclusion

Our findings suggested that a contralateral C7 nerve transfer, which has no additional adverse effects on the healthy upper limb, is a preferable method to restore motor function.

Site of Nerve Division Affects Pain-Related Behavior and Spinal Cord Glial Proliferation after C7 Neurotomy in a Rat Stroke Model

Objective

This study aimed to evaluate whether the site of C7 neurotomy affects spinal cord glial cell activation and pain-related behavior on the paralyzed side in a rat stroke model.

Methods

After middle cerebral artery occlusion (MCAO) was induced in male Sprague-Dawley rats, they underwent C7 neurotomy 0, 2, and 4 mm distal to the intervertebral foramen on the paralyzed side. Pain-related behavior and immunofluorescence examination of spinal cord glial cell activation in the ipsilateral C7 dorsal horn were evaluated.

Results

Mechanical paw withdrawal threshold (MPWT) was lower, and the number of microglia and astrocytes (/mm²) was higher as the distance between the site of C7 neurotomy and the intervertebral foramen decreased from 4 mm to 0.

Conclusion

The site of C7 neurotomy affects MPWT and spinal cord glial proliferation in rats with MCAO. Nerve division closer to intervertebral foramen resulted in lower MPWT and higher degree of glial proliferation in the spinal cord.

A new approach for contralateral C7 nerve transfer via retrospinal route

Anterior and posterior approaches exist for the treatment of spinal pathologies. Anatomically, the 7th cervical spinal nerve(C7)crosses the C6-C7 intervertebral foramen bilaterally, allowing contralateral prevertebral or posterior C7 nerve transfer to be used. The advantage of the posterior rather than the anterior spinal approach is that it does not require retraction of important blood vessels, nerves, or other structures. In this paper, we describe transfer of the contralateral C7 nerve using a posterior approach.

Contralateral C7 nerve transfer in the treatment of upper-extremity paralysis: a review of anatomical basis, surgical approaches, and neurobiological mechanisms

The previous three decades have witnessed a prosperity of contralateral C7 nerve (CC7) transfer in the treatment of upper-extremity paralysis induced by both brachial plexus avulsion injury and central hemiplegia. From the initial subcutaneous route to the pre-spinal route and the newly-established post-spinal route, this surgical operation underwent a series of innovations and refinements, with the aim of shortening the regeneration distance and even achieving direct neurorrhaphy. Apart from surgical efforts for better peripheral nerve regeneration, brain involvement in functional improvements after CC7 transfer also stimulated scientific interest. This review summarizes recent advances of CC7 transfer in the treatment of upper-extremity paralysis of both peripheral and central causes, which covers the neuroanatomical basis, the evolution of surgical approach, and central mechanisms. In addition, motor cortex stimulation is discussed as a viable rehabilitation treatment in boosting functional recovery after CC7 transfer. This knowledge will be beneficial towards improving clinical effects of CC7 transfer.

L4-to-L4 nerve root transfer for hindlimb hemiplegia after hypertensive intracerebral hemorrhage

There is no effective treatment for hemiplegia after hypertensive intracerebral hemorrhage. Considering that the branches of L4 nerve roots in the lumbar plexus root control the movement of the lower extremity anterior and posterior muscles, we investigated a potential method of nerve repair using the L4 nerve roots. Rat models of hindlimb hemiplegia after a hypertensive intracerebral hemorrhage were established by injecting autogenous blood into the posterior limb of internal capsule. The L4 nerve root on the healthy side of model rats was transferred and then anastomosed with the L4 nerve root on the affected side to drive the extensor and flexor muscles of the hindlimbs. We investigated whether this method can restore the flexible movement of the hindlimbs of paralyzed rats after hypertensive intracerebral hemorrhage. In a beam-walking test and ladder rung walking task, model rats exhibited an initial high number of slips, but improved in accuracy on the paretic side over time. At 17 weeks after surgery, rats gained approximately 58.2% accuracy from baseline performance and performed ankle motions on the paretic side. At 9 weeks after surgery, a retrograde tracing test showed a large number of fluoro-gold-labeled motoneurons in the left anterior horn of the spinal cord that supports the L4-to-L4 nerve roots. In addition, histological and ultramicrostructural findings showed axon regeneration of motoneurons in the anterior horn of the spinal cord. Electromyography and paw print analysis showed that denervated hindlimb muscles regained reliable innervation and walking coordination improved. These findings suggest that the L4-to-L4 nerve root transfer method for the treatment of hindlimb hemiplegia after hypertensive intracerebral hemorrhage can improve the locomotion of hindlimb major joints, particularly of the distal ankle. Findings from study support that the L4-to-L4 nerve root transfer method can effectively repair the hindlimb hemiplegia after hypertensive intracerebral hemorrhage. All animal experiments were approved by the Animal Ethics Committee of the First Affiliated Hospital of Nanjing Medical University (No. IACUC-1906009) in June 2019.

[Research progress of contralateral C 7 nerve root transfer via prevertebral pathway]

OBJECTIVE

To review the research progress on the establishment of prevertebral pathway in the treatment of unilateral total brachial plexus injury, cerebral palsy, stroke, and traumatic brain injury by contralateral C 7 nerve root transfer.

METHODS

The literature about contralateral C 7 nerve root transfer via prevertebral pathway at home and abroad was extensively reviewed, and the development, changes, advantages and disadvantages of various operation methods were analyzed and summarized.

RESULTS

After unilateral total brachial plexus injury, cerebral palsy, stroke, and traumatic brain injury, it can be repaired by a variety of surgical methods of the contralateral C 7 nerve root transfer via prevertebral pathway, which include the anterior subcutaneous tissue tunnel of the vertebral body, the passage under the sternocleidomastoid muscle, the posterior pharyngeal space and the anterior vertebral fascia passage, the modified posterior esophageal anterior vertebral passage, the anterior vertebral passage that cuts off the bilateral anterior scalene, and Huashan anterior pathway, etc. Among them, how to establish the shortest, safe, and effective way of anterior vertebral canal has been paid more attention and discussed by peripheral nerve repair doctors.

CONCLUSION

It is a safe and effective surgical method to repair unilateral total brachial plexus injury, cerebral palsy, stroke, and traumatic brain injury patients with contralateral C 7 nerve root transfer via prevertebral pathway.