Reconstruction of reflex pathways to the atonic bladder after conus medullaris injury: preliminary clinical results

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.

Clinical guidelines for neurorestorative therapies in spinal cord injury (2021 China version)

Treatment of spinal cord injury (SCI) remains challenging. Considering the rapid developments in neurorestorative therapies for SCI, we have revised and updated the Clinical Therapeutic Guidelines for Neurorestoration in Spinal Cord Injury (2016 Chinese version) of the Chinese Association of Neurorestoratology (Preparatory) and China Committee of International Association of Neurorestoratology. Treatment of SCI is a systematic multimodal process that aims to improve survival and restore neurological function. These guidelines cover real-world comprehensive neurorestorative management of acute, subacute, and chronic SCI and include assessment and diagnosis, pre-hospital first aid, treatment, rehabilitation, and complication management.

Clinical Neurorestorative Therapeutic Guidelines for Spinal Cord Injury (IANR/CANR version 2019)

Functional restoration after spinal cord injury (SCI) is one of the most challenging tasks in neurological clinical practice. With a view to exploring effective neurorestorative methods in the acute, subacute, and chronic phases of SCI, “Clinical Therapeutic Guidelines of Neurorestoration for Spinal Cord Injury (China Version 2016)” was first ​proposed in 2016 by the Chinese Association of Neurorestoratology (CANR). Given the rapid advances in this field in recent years, the International Association of Neurorestoratology (IANR) and CANR formed and approved the “Clinical Neurorestorative Therapeutic Guidelines for Spinal Cord Injury (IANR/CANR version 2019)”. These guidelines mainly introduce restoring damaged neurological structure and functions by varying neurorestorative strategies in acute, subacute, and chronic phases of SCI. These guidelines can provide a neurorestorative therapeutic standard or reference for clinicians and researchers in clinical practice to maximally restore functions of patients with SCI and improve their quality of life.

The translational potential of this article

This guideline provided comprehensive management strategies for SCI, which contains the evaluation and diagnosis, pre-hospital first aid, treatments, rehabilitation training, and complications management. Nowadays, amounts of neurorestorative strategies have been demonstrated to be benefit in promoting the functional recovery and improving the quality of life for SCI patients by clinical trials. Also, the positive results of preclinical research provided lots of new neurorestorative strategies for SCI treatment. These promising neurorestorative strategies are worthy of translation in the future and can promote the advancement of SCI treatments.

Anatomical Feasibility of Extradural Transferring S2 and S3 Ventral Roots to S1 Ventral Root for Restoring Neurogenic Bladder in Spinal Cord Injury

STUDY DESIGN

Anatomic study in six formalin-fixed cadavers.

OBJECTIVE

To determine the anatomical feasibility of transferring the S2 and S3 ventral roots (VRs) to S1 VR as a method for restoring bladder dysfunction in spinal cord injury.

SUMMARY OF BACKGROUND DATA

A large quantity of researches of neuroanastomosis methods have been used for treating the bladder dysfunction in spinal cord injury. However, some limitations retard the development of those studies.

METHODS

In this study, six formalin-fixed cadavers (four males, two females) were dissected. The feasibility of exposing the S1, S2, and S3 extradural nerve roots by the limited laminectomy, isolating the VR and dorsal roots from each extradural nerve root and transferring the S2,S3 VRs to the S1 VR were assessed. The pertinent distances and the nerve cross-sectional areas in each specimen were measured. The morphology of each nerve root was observed by hematoxylin-eosin staining.

RESULTS

The limited laminectomy was performed to expose the S1 to S3 extradural nerve roots. The VRs could be isolated from each extradural nerve root at the location of the dorsal root ganglion and the hematoxylin-eosin staining showed that there were some connective tissues separating the VRs from the corresponding dorsal root ganglion. The S2 and S3 VRs have sufficient lengths to be transferred to S1 VR without grafting. The mean cross-sectional area of the S1 VR was 2.60 ± 0.17 mm, and that was 1.02 ± 0.32 mm and 0.51 ± 0.21 mm of the S2 and S3 VRs, respectively.

CONCLUSION

This study demonstrated that use of the S2 and S3 VRs for extradural transfer to S1 VR for restoring bladder dysfunction is surgically feasible.

LEVEL OF EVIDENCE

5.

The feasibility study of extradural nerve anastomosis technique for canine bladder reinnervation after spinal cord injury

OBJECTIVE

Intradural nerve anastomosis for bladder innervation has been demonstrated to be useful. However, its clinical application remains limited because of the complex surgery, its complications and extensive bony destruction. The purpose of the current study was to demonstrate the feasibility of extradural spinal root anastomosis for bladder innervation in canines.

METHODS

Ten beagle dogs were used. The length of the extradural segment of the nerve root, upper nerve root outlet (the point at which it emerges from the spinal dura mater) to S2 (dS2), the S3 (dS3) nerve root outlet distance, and the diameters of the extradural spinal roots were measured. The numbers of nerve fibers from L6 to S3 ventral roots were calculated using immunohistochemical staining.

RESULTS

The extradural spinal roots could be divided into a ventral root (VR) and a dorsal root (DR) before the ganglionic enlargement of the dorsal root, and the extradural motor nerve roots situate ventrally to their corresponding sensory nerve roots. The extradural nerve root lengths of S1 and parts of L7 were longer than the corresponding dS2. The numbers of nerve and motor nerve fibers, and the diameters of extradural nerve roots, were gradually descending from L6 to S3.

CONCLUSION

The S1 VRs and parts of the L7 VRs can be extradurally anastomosed to the S2 nerves without tension. A nerve graft was needed for extradural anastomosis of L6 VRs and parts of L7 VRs to S2 VRs. This study demonstrated the feasibility of extradural spinal nerve anastomosis for treating neurogenic bladder in canines.

Lack of efficacy of an intradural somatic-to-autonomic nerve anastomosis (Xiao procedure) for bladder control in children with myelomeningocele and lipomyelomeningocele: results of a prospective, randomized, double-blind study

OBJECTIVE Xiao et al. and other investigators have studied an intradural somatic-to-autonomic (e.g., L-5 to S3-4) nerve transfer as a method to create a reflex arc to allow bladder emptying in response to cutaneous stimulation (the Xiao procedure). In previous clinical studies of patients with spinal dysraphism who underwent the Xiao procedure, high success rates (70%-85%) were reported for the establishment of a "skin-CNS-bladder" reflex arc that allows spontaneous, controlled voiding in children with neurogenic bladder dysfunction. However, many of these studies did not use blinded observers, did not have control groups, and/or featured only limited follow-up durations. METHODS A randomized, prospective, double-blind trial was initiated in March 2009, enrolling children with myelomeningocele (MM), lipomyelomeningocele (LMM), and neurogenic bladder dysfunction who were scheduled for spinal cord detethering (DT) for the usual indications. At the time of DT, patients were randomized between 2 arms of the study: half of the patients underwent a standard spinal cord DT procedure alone (DT group) and half underwent DT as well as the Xiao procedure (DT+X group). Patients, families, and study investigators, all of whom were blinded to the surgical details, analyzed the patients' strength, sensory function, mobility, voiding, and urodynamic bladder function before surgery and at regular intervals during the 3-year follow-up. RESULTS Twenty patients were enrolled in the study: 10 underwent only DT and the other 10 underwent DT+X. The addition of the Xiao procedure to spinal cord DT resulted in longer operative times (p = 0.024) and a greater chance of wound infection (p = 0.03). Patients in both treatment arms could intermittently void or dribble small amounts of urine (< 20% total bladder capacity) in response to scratching in dermatomes T-9 through S-2 using a standardized protocol, but the voiding was not reproducible and the volume voided was not clinically useful in any patient. Voiding in response to scratching was not more frequent in patients who underwent DT+X compared with those who underwent only DT. Bladder contractions in response to scratching occurred in both treatment arms at various intervals after surgery, but they were not more reproducible or more frequent in the patients who underwent the Xiao procedure than in the patients who did not. No patient in either treatment arm was continent of urine before, during, or after the study. CONCLUSIONS Patients with MM and LMM who underwent the Xiao procedure during spinal cord DT were no more likely to be able to void, to control their urination, to achieve continence, or to have a demonstrable urodynamic bladder contraction in response to cutaneous stimulation than patients who underwent only spinal cord DT. This study, in the context of disappointing results reported in other recent studies of the Xiao procedure, raises doubts about the clinical applicability of this procedure in humans until further basic science research is performed.

Reconstruction of atonic bladder innervation after spinal cord injury: A bladder reflex arc with afferent and efferent pathways

Background Establishing bladder reflex arcs only with the efferent pathway to induce micturition after spinal cord injury (SCI) has been successful. However, the absence of sensory function and micturition desires can lead to serious complications. Objectives To reconstruct a bladder reflex arc with both afferent and efferent pathways to achieve atonic bladder innervation after SCI. Methods A reflex arc was established by microanastomosis of the S2 dorsal root to the peripheral process of the L5 dorsal ganglion and the L5 ventral root to the S2 ventral root. The functions of the reflex arc were evaluated using electrophysiology, wheat germ agglutinin-horseradish peroxidase (WGA-HRP) tracing, and calcitonin gene-related peptide (CGRP) immunocytochemistry analysis. Hind-paw motion was evaluated by CatWalk gait. Results Compound action potentials and compound muscle action potentials were recorded at the right L5 dorsal root following electrical stimulation of right S2 dorsal root. Similar to the control side, these were not significantly different before or after the spinal cord destruction between L6 and S4. WGA-HRP tracing and CGRP immunocytochemistry showed that construction of the afferent and efferent pathways of the bladder reflex arc encouraged axonal regeneration of motor and sensory nerves, which then made contact with the anterior and posterior horns of the spinal cord, ultimately reestablishing axoplasmic transportation. Gait analysis showed that at 3 months following the operation, only the regularity index was significantly different as compared with 1 day before the operation, other parameters showing no difference. Conclusion Bladder reflex arc with the afferent and efferent pathways reconstructs the micturition function without great influence on the motion of leg.

Consensus of clinical neurorestorative progress in patients with complete chronic spinal cord injury

Currently, there is a lack of effective therapeutic methods to restore neurological function for chronic complete spinal cord injury (SCI) by conventional treatment. Neurorestorative strategies with positive preclinical results have been translated to the clinic, and some patients have gotten benefits and their quality of life has improved. These strategies include cell therapy, neurostimulation or neuromodulation, neuroprosthesis, neurotization or nerve bridging, and neurorehabilitation. The aim of this consensus by 31 experts from 20 countries is to show the objective evidence of clinical neurorestoration for chronic complete SCI by the mentioned neurorestorative strategies. Complete chronic SCI patients are no longer told, "nothing can be done." The clinical translation of more effective preclinical neurorestorative strategies should be encouraged as fast as possible in order to benefit patients with incurable CNS diseases. This manuscript is published as part of the International Association of Neurorestoratology (IANR) special issue of Cell Transplantation.

Extradural nerve anastomosis technique for bladder reinnervation in spinal cord injury: anatomical feasibility study in human cadavers

STUDY DESIGN

An anatomic study of extradural spinal root in 9 embalmed cadavers.

OBJECTIVE

To ascertain the anatomical parameters of the extradural spinal root and to demonstrate the feasibility of spinal root anastomoses without opening the spinal dura mater.

SUMMARY OF BACKGROUND DATA

Intradural anastomosis of the spinal root has made breakthrough progress in treating neurogenic bladder in spinal cord injury. However, because of the complex surgical procedures and extensive bony destruction, its clinical use is not widely promoted.

METHODS

Nine formalin-fixed cadavers were used. The distance between the nerve root outlet and ganglion center, the neighboring nerve root-outlet distance, and the gross anatomy of the extradural spinal root were measured with a surgical microscope. The number of nerve fibers from the T7 to S4 ventral roots (VRs) was calculated by immunohistochemical staining.

RESULTS

The longest and shortest lengths of the extradural spinal root were observed at the S4 and T7 levels, with average values of 33.29 and 6.06 mm, respectively. The longest distance between the adjacent nerve root outlets was observed at L1-L2 (mean, 29.16 mm), and shortest at S3-S4 (mean, 11.79 mm). After leaving the dural sac, the spinal root descends in the spinal canal until reaching the corresponding intervertebral foramina, and the motor nerve roots still lie ventrally to the sensory nerve roots. The largest and smallest numbers of nerve fibers were observed at the L3 and S4 levels (mean, 9169 and 1356, respectively).

CONCLUSION

The dorsal roots and VRs can both be successfully harvested and identified outside the dural sac. The S1 VR can be anastomosed to the S2 VR extradurally without nerve grafts. For extradural neuroanastomosis of the thoracic VRs to the S2 VR, a nerve graft is required. In addition, there are a sufficient number of nerve fibers for functional bladder recovery at the T7-T12 and S1 levels. This study supports the feasibility of extradural spinal root anastomosis as a modified surgical method for treating neurogenic bladder.

LEVEL OF EVIDENCE

N/A.

Attempted bladder reinnervation and creation of a scratch reflex for bladder emptying through a somatic-to-autonomic intradural anastomosis

An intradural somatic-to-autonomic anastomosis, or Xiao procedure, has been described to create a "skin-CNS-bladder" reflex that improves bladder and bowel function in patients with neurogenic bladder and bowel dysfunction. The authors present their experience with a 10-year-old boy with chronic neurogenic bladder and bowel dysfunction related to spinal cord injury who underwent the Xiao procedure. After undergoing a left L-5 ventral root to left S2-3 intradural anastomosis, the patient reported that his bladder and bowel dysfunction improved between 6 and 12 months. Two years after the procedure, however, he reported that there was no change in his bladder or bowel dysfunction as compared with his condition prior to the procedure. Frequent, systematic multidisciplinary evaluations produced conflicting data. Electrophysiological and histological evaluation of the previously performed anastomosis during surgical reexploration 3 years after the Xiao procedure revealed that the anastomosis was in anatomical continuity but neuroma formation had prevented reinnervation. Nerve action potentials were not demonstrable across the anastomosis, and stimulation of the nerve above and below the anastomosis created no bladder or perineal contractions. This is the first clinical report on the outcome of the Xiao procedure in a child with spinal cord injury outside of China. It is impossible to draw broad conclusions about the efficacy of the procedure based on a single patient with no demonstrable benefit. However, future studies should carefully interpret transient improvements in bladder function, urodynamic findings, and the patient's ability to void in response to scratching after the Xiao procedure. The authors' experience with the featured patient, in whom reinnervation could not be demonstrated, suggests that such changes could be related to factors other than the establishment of a skin-CNS-bladder reflex as a result of a somatic-to-autonomic anastomosis.

Transfer of normal S1 nerve root to reinnervate atonic bladder due to conus medullaris injury

INTRODUCTION

Neurogenic bladder dysfunction after spinal cord injury (SCI) is a major medical and social problem. In this study we assessed the effectiveness of neurogenic bladder reinnervation in patients with SCI using a normal S1 nerve root.

METHODS

Nine patients with bladder dysfunction caused by injury to the low conus medullaris (S2-S5) underwent a novel surgical procedure in which the unilateral proximal end of the S1 ventral root (VR) was anastomosed to the distal end of the S2 and S3 VRs.

RESULTS

Seven patients regained satisfactory bladder control within 8-12 months after VR microanastomosis. The average residual urine volume decreased from 186.0 ± 35.0 ml to 43.0 ± 10.0 ml, and no urinary infections occurred.

CONCLUSIONS

These results suggest the effectiveness of bladder innervation by S1 nerve transfer, which could provide a new approach for the reconstruction of atonic bladder function caused by low conus medullaris injuries.

Nerve transfer strategies for spinal cord injury

BACKGROUND

Spinal cord injury (SCI) is a devastating condition, which beleaguers its victims with long-term health issues. Nerve transfer is a feasible option for restoration of critical limb function in patients with SCI that potentially improves independence and quality of life.

METHODS

This article delineates the general principles of nerve transfer and its specific application pertinent to SCI. The available nerve transfer strategies are described based on the targeted limb function, mostly involving critical upper extremity function. The role of nerve transfer for paraplegia, diaphragm reanimation, and bladder reinnervation is also discussed.

RESULTS

Nerve transfer offers several advantages over the traditionally used tendon transfer.

CONCLUSIONS

Nerve transfer does not require prolonged immobilization and provides greater functional gain for a given transfer. Reconstruction of several facets of upper limb function potentially can be performed in a single stage. The merits of nerve transfer deserve further study to evaluate its value for spinal cord injury in humans.

Low-frequency electrotherapy for female patients with detrusor underactivity due to neuromuscular deficiency

Introduction and hypothesis

The aim of the study was to assess the efficacy of low-frequency electrotherapy (LFE) for female patients with early-stage detrusor underactivity (DUA) due to neuromuscular deficiency.

Methods

A total of 102 female patients were divided randomly into four groups: LFE-NC (normal compliance), LFE-LC (low compliance), CON (control)-NC and CON-LC. Patients in the LFE-NC and LFE-LC groups received LFE, and those in the CON-NC and CON-LC groups received conservative treatment. Urodynamic evaluation was performed before and after treatment.

Results

After treatment, 82 % of the LFE-NC regained detrusor contractility, whereas only 2 (8 %) of the CON-NC had normal detrusor contraction. None of LFE-LC or CON-LC regained detrusor contractility (p < 0.01). The per cent of LFE-NC who relied on catheterization for bladder emptying decreased by 43 % (p < 0.01). Those in the LFE-LC, CON-NC and CON-LC groups decreased by only 4, 12 or 0 % (p > 0.05).

Conclusions

LFE was more effective for DUA patients with normal compliance; these patients benefited from LFE, but DUA patients with low compliance did not.

Micturition reflex arc reconstruction including sensory and motor nerves after spinal cord injury: urodynamic and electrophysiological responses

OBJECTIVE

To evaluate artificial reflex arcs for micturition using urodynamics and electrophysiological recordings.

DESIGN

Sixteen beagles were equally and randomly divided into two groups.

METHODS

In group A, anastomosis of the proximal end of the left L7 ventral root (VR) and distal end of the left S2 VR was performed, as well as anastomosis of the L7 dorsal root (DR) and S2 DR to reconstruct the sensory and the motor function of the bladder. In group B the proximal end of the left L7 VR and the distal end of the left S2 VR were anastomosed, while the left L7 DR was kept intact to reconstruct the motor function of the bladder. Outcome measures included electrophysiological testing and the urodynamic measures. In addition, we also monitored urinary infection rates.

RESULTS

Stimulation to the left S2 DR in groups A and B both elevated the bladder pressure before and after the spinal lower motor neuron lesion. Single stimulation of the two groups both elicited evoked action potentials. Urinary infections occurred in group A (three occurrences) and in group B (eight occurrences) during the 3 months after the spinal lower motor neuron lesion.

CONCLUSION

Data showed that both reconstructive methods could induce bladder micturition and evoked action potentials. However, in group A the micturition response was better and the urinary infection rates were lower after the spinal lower motor neuron lesion. Thus, the artificial physiological reflex arc reconstruction method used in group A, with sensory input above the lesion, might provide a better alternative in clinical practice.

[Bladder reinnervation with creation of a "somato-autonomic" reflex pathway in spinal cord injured or spina bifida, a new way for treatment?]

CONTEXT

The restoration of physiological micturition is a major objective for patients presenting a medullary injury, which is not possible with current treatment. Several recent studies have purposed some techniques for bladder reinnervation. Their purpose was to begin a voluntary micturition by the stimulation of an artificial reflex arc created by the anastomosis of a somatic root with a root innervating the bladder.

MATERIALS AND METHODS

We searched on Medline and Cochrane for articles in English. The keywords used were: bladder reinnervation, spinal cord injury neurogenic bladder, reflex pathway for micturition.

RESULTS

These studies reported a variable efficacy as high as 85% of the treated patients. These patients could begin micturition voluntarily, associated with a significant improvement observed in their postoperative urodynamic evaluation. In fact, an improvement of the detrusor external sphincter dyssynergia and/or bladder overactivity was reported, and the patients presented a better quality of life by the control of their micturition associated with an improvement in continence with no need for intermittent catheterisation. However, these results were variable from one study to the other, and certain results seem difficult to explain notably concerning the abolition of bladder overactivity and the improvement of the detrusor external sphincter dyssynergia.

CONCLUSION

Further experimental studies are still required, notably with animals to confirm the encouraging results of these initial studies, and to better understand the mechanism before possible routine patient use.

Reinnervation of atonic bladder after conus medullaris injury using a modified nerve crossover technique in canines

BACKGROUND

Neurogenic bladder represents a major cause of morbidity in patients with spinal cord injuries (SCI). Herein, we evaluated a novel reconstructive surgical technique designed to restore afferent and efferent nerve function in atonic bladder caused by conus medullaris injury.

MATERIALS AND METHODS

A new reflex pathway was established by extradural transfer of the left L5 ventral root (VR) to the left S2 VR root together with extradural postganglionic spinal nerve transfer of the L5 dorsal root (DR) to the S2 DR with a nerve graft in a canine model. The corresponding nerves on the right side were kept intact and served as a control. After the new reflex pathway was reestablished, the early function of the reflex arc was evaluated by electrophysiologic study, intravesical pressure, and histologic examination.

RESULTS

Action potential (AP) curves were recorded with single focal stimulation of the left S2 DR before and after the spinal cord was destroyed horizontally between the L6 and S3 levels. Bladder contraction was successfully initiated by trains of stimuli targeting the left L5-S2 DR anastomosis. Achievable bladder pressures and the amplitude of bladder smooth muscle complex action potentials were unchanged before and after induced paraplegia and were comparable to those of the control. Prominent axonal sprouting was observed in the distal region of the nerve graft.

CONCLUSION

Both afferent and efferent nerve pathways in the atonic bladder were reconstructed by suprasacral motor-to-motor and sensory-to-sensory extradural nerve transfer in canines. Taken together, these findings suggest a new potential clinical approach for restoring bladder function in individuals with paraplegia.