Functional posterior rhizotomy: the Tokyo experience

A systematic review of complications following selective dorsal rhizotomy in cerebral palsy

PURPOSE

The literature lacks a concise overview of complications secondary to selective dorsal rhizotomy (SDR). The aim of this study was to systematically review the literature regarding post-SDR complications, and to present them concisely.

METHODS

The protocol of the review was registered on Open Science Framework. Studies on SDR in cerebral palsy were included. The studies to be included used SDR for management of spasticity in patients with cerebral palsy. The long-term complications of SDR mentioned in the articles were inventoried.

RESULTS

Thirty studies were included for qualitative review. Twenty-one types of complication were identified. Structural complications were the commonest: scoliosis (214/1,043, 20.5%), hyperlordosis (101/552, 18.2%), spondylolysis (55/574, 9.5%) and kyphosis (67/797, 8.4%). Neurological complications comprised constipation (70/485, 14.4%), hip subluxation (3/29, 10.3%), spastic syndrome (4/47, 8.5%), sensory changes (106/1290, 8.2%) and urinary incontinence (61/1013, 6%).

CONCLUSION

This review should help surgeons and parents alike to know about the potential complications of SDR. Complications may affect quality of life and should be weighed. Although the majority of these complications were managed conservatively, there would still be a physical, psychological and financial burden which should be taken into account. Screening should be continued vigorously throughout skeletal growth and at reduced frequency thereafter, for timely intervention in case of structural complications.

Selective dorsal rhizotomy: functional anatomy of the conus-cauda and essentials of intraoperative neurophysiology

INTRODUCTION

Spasticity is the result of an exaggeration of the monosynaptic muscle stretch reflex due to lesions affecting the central nervous system, in particular an upper motor neuron lesion. Selective dorsal rhizotomy (SDR) is a surgical technique developed to treat spastic diplegia, one of the common forms of cerebral palsy, resulting from the lack of supraspinal inhibitory controls. The aim of SDR is to identify and cut a critical amount of the sensory rootlets, in particular those contributing the most to spasticity, in order to relieve the patient from lower limb spasticity while preserving motor strength and sphincter control. Various surgical techniques to perform SDR have been proposed over time. Similarly, intraoperative neurophysiology (ION)-first introduced by Fasano and colleagues in 1976-is a safe and effective tool to guide the surgeon in the procedure of SDR, but different ION strategies are used by different authors, and the value of ION itself has been questioned.

METHODS

The purpose of this paper is to review the anatomo-physiological background of SDR, the historical development of the surgical technique, and the essential principles of ION.

RESULTS

While some surgeons privilege a single-level approach and others a multi-level approach, nowadays, there are still neither agreement nor guidelines on the percentage of roots to be cut. Rather, a tailored approach based on both the preoperative functional status as well as intraoperative ION findings seems reasonable. ION is considered not essential to decide the percentage of roots to cut, but it assists to distinguish between ventral and dorsal roots, and to preserve sphincterial function, whenever S2 rootlets are included in SDR.

CONCLUSIONS

To optimize the balance between reduction of spasticity and preservation of motor strength while minimizing the neurological damage remains the main goal of SDR.

Pudendal mapping of S1 rootlets in a functional posterior rhizotomy: when an S1 posterior root shows a high pudendal dorsal action potential-a technical note

BACKGROUND

The standard level for lesioning in a functional posterior rhizotomy (FPR) ranges from L2 to S1/S2. Lesioning of the S1 and S2 rootlets strongly correlates with a reduction in ankle spasticity. In the Japanese population, the S2 root often shows the highest dorsal root action potentials (DAPs) in the afferent fibers of the pudendal nerve and is not lesioned to preserve postoperative urinary function. Thus, cutting of the S1 root plays a key role in reducing ankle spasticity in FPR. However, on rare occasions, even an S1 root may show high DAP in the afferent fibers of the pudendal nerve.

PURPOSE

The present, brief, technical note aimed to describe how an S1 root with a relatively high DAP in the afferent fibers of the pudendal nerve may be handed.

METHODS

In the procedure, the S1 root is divided into several rootlets, and each rootlet is tested for the pudendal mapping. A train of electrical stimuli is delivered to each rootlet in the standard FPR. If electromyography (EMG) findings after electrical stimulation are highly abnormal while the pudendal mapping demonstrates no or a relatively low DAPs, the rootlet is cut. In contrast, even if the rootlet shows highly abnormal EMG findings, it is preserved if mapping demonstrates a relatively high DAP.

CONCLUSION

The S1 pudendal mapping is combined with EMG findings to achieve satisfactory reduction in ankle spasticity while preserving urological function.

Frequency distribution in intraoperative stimulation-evoked EMG responses during selective dorsal rhizotomy in children with cerebral palsy-part 1: clinical setting and neurophysiological procedure

INTRODUCTION

Selective dorsal rhizotomy (SDR) consists of microsurgical partial deafferentation of sensory nerve roots (L1-S2). It is primarily used today in decreasing spasticity in young cerebral palsy (CP) patients. Intraoperative monitoring (IOM) is an essential part of the surgical decision-making process, aimed at improving functional results. The role played by SDR-IOM is examined, while realizing that connections between complex EMG responses to nerve-root stimulation and a patient's individual motor ability remain to be clarified.

METHODS

We conducted this retrospective study, analyzing EMG responses in 146 patients evoked by dorsal-root and rootlet stimulation, applying an objective response-classification system, and investigating the prevalence and distribution of the assessed grades. Part1 describes the clinical setting and SDR procedure, reintroduced in Germany by the senior author in 2007.

RESULTS

Stimulation-evoked EMG response patterns revealed significant differences along the segmental levels. More specifically, a comparison of grade 3+4 prevalence showed that higher-graded rootlets were more noticeable at lower nerve root levels (L5, S1), resulting in a typical rostro-caudal anatomical distribution.

CONCLUSIONS

In view of its prophylactic potential, SDR should be carried out at an early stage in all CP patients suffering from severe spasticity. It is particularly effective when used as an integral part of a coordinated, comprehensive spasticity program in which a team of experts pool their information. The IOM findings pertaining to the anatomical grouping of grades could be of potential importance in adjusting the SDR-IOM intervention to suit the specific individual constellation, pending further validation.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT03079362.

Clinically practical formula for preoperatively estimating the cutting rate of the spinal nerve root in a functional posterior rhizotomy

OBJECTIVE

A functional posterior rhizotomy (FPR) ideally involves minimal cutting of the posterior root while providing maximal reduction of disabling spasticity. However, the ideal cutting rate has yet to be determined. It was hypothesized that the cutting rate of the posterior root would negatively correlate with preoperative motor function in children with spasticity.

METHODS

Children who underwent an FPR between March 1996 and March 2017 and whose pre- and postoperative data were followed more than a year were enrolled. The preoperative Gross Motor Function Measure (GMFM) score and the overall cutting rate of the posterior root were plotted on a scatter plot, and a simple linear regression analysis was performed. The rationale for the cutting rate of the posterior root was tested by postoperative chronological changes in the GMFM score up to 5 years after the FPR. The Gross Motor Function Classification System (GMFCS) was used to group the children. The postoperative and preoperative GMFM were compared at each GMFCS level.

RESULTS

One hundred thirty-seven children (aged 2 to 19 years old, mean 5.9 years old) met the selection criteria. The cutting rate of the posterior root ranged from 17 to 83%, (mean 48.3%). A scatter plot was then made using GMFM scores between 10 and 90. The formula for the simple linear regression analysis was y = - 0.5539x + 73.896 (x, GMFM score; y, overall cutting rate (%)). The formula was further approximated based on the scatter plot findings as y = 100 - x. The postoperative GMFM showed an improved average score for all GMFCS levels although statistically significant improvement at postoperative 5 years was confirmed in only the GMFCS level 1 group.

CONCLUSIONS

The findings of this study supported the hypothesis of the negative correlation of the cutting rate of the posterior root with preoperative motor function in children with spasticity. The amount of posterior nerve root/rootlet cutting during FPR negatively correlated with the preoperative GMFM score. The approximated formula is simple, practical for clinical use, and helpful for preoperatively estimating the required overall cutting rate for the posterior root. The suggested cutting rate induced by the approximated formula should be used as a reference value and be modified according to preoperative motor function, severity and distribution of spasticity, the result of intraoperative neurophysiology, and other factors.

Single-level selective dorsal rhizotomy for spastic cerebral palsy

The management of cerebral palsy (CP) is complex and requires a multidisciplinary approach. Selective dorsal rhizotomy (SDR) is a neurosurgical technique that aims to reduce spasticity in the lower limbs. A minimally invasive approach to SDR involves a single level laminectomy at the conus and utilises intraoperative electromyography (EMG). When combined with physiotherapy, SDR is effective in selected children and has minimal complications. This review discusses the epidemiology of CP and the management using SDR within an integrated multidisciplinary centre. Particular attention is given to the single-level laminectomy technique of SDR and its rationale, and the patient workup, recovery and outcomes of SDR.

Neurosurgical Management of Childhood Spasticity: Functional Posterior Rhizotomy and Intrathecal Baclofen Infusion Therapy

A paradigm shift is currently ongoing in the treatment of spasticity in childhood in Japan. Functional posterior rhizotomy (FPR), which was first introduced to Japan in 1996, is best indicated for children with spastic cerebral palsy, regardless of the clinical severity of spasticity. Surgery is generally carried out in the cauda equina, where the posterior root is separated from the anterior one, and neurophysiological procedures are used to judge which nerve root/rootlet should be cut. The outcome of FPR is favorable for reducing spasticity in the long-term follow-up. Intrathecal baclofen (ITB) treatment for childhood spasticity was approved in 2007 in Japan and the number of children undergoing ITB pump implantation has been gradually increasing. ITB treatment is best indicated for children with severe spasticity, especially those with dystonia, regardless of the pathological background. Since it is a surgery performed to implant foreign bodies, special attention should be paid to avoid perioperative complications such as CSF leakage, meningitis, and mechanical failure. Severely disabled children with spasticity would benefit most from ITB treatment. We would especially like to emphasize the importance of a strategic approach to the treatment of childhood spasticity. The first step is to reduce spasticity by FPR, ITB, and botulinum toxin injection. The second step is to aim for functional improvement after controlling spasticity. Traditional orthopedic surgery and neuro-rehabilitation form the second step of treatment. The combination of these treatments that allows them to complement each other is the key to a successful treatment of childhood spasticity.

Pudendal afferents mapping in posterior sacral rhizotomies

BACKGROUND

The effectiveness of pudendal afferents mapping in posterior sacral rhizotomies needs to be reviewed.

OBJECTIVE

To evaluate the effectiveness of pudendal afferents mapping for both the dorsal penile or clitoral nerve and the inferior anal nerve to decrease the risk of postoperative bowel and bladder dysfunction when the sacral nerve roots are candidates for rhizotomies.

METHODS

A retrospective review of 101 Asian children who underwent functional posterior rhizotomies with pudendal afferents mapping for spastic paresis was performed.

RESULTS

Pudendal mapping was successful in 75 of 81 patients. The highest activity of afferent fibers of the dorsal penile or clitoral nerve was demonstrated at the S1 roots in 13.3%, at the S2 in 79.3%, and at the S3-5 in 7.3%. Considerable activity of the dorsal penile or clitoral nerve was recorded at 40% of the S1 roots, at 99.3% of the S2 roots, and at 52% of the S3-5 roots. The highest activity of afferent fibers of the inferior anal nerve was demonstrated at S2 roots in 42% and at S3-5 roots in 58%. Considerable activity of the inferior anal nerve was recorded at 10.7% of S1 roots, at 89.3% of S2 roots, and at 76.7% of S3-5 roots. The pathological S1 roots were divided into 3 to 4 rootlets, and the rootlets with significant afferent activity were preserved. None of the 75 patients experienced long-term bowel or bladder complications.

CONCLUSION

Pudendal afferent mapping identified the sacral rootlets involved with genital and anal sensation. The preservation of such rootlets in sacral rhizotomies is considered to be important for minimizing postoperative bladder and bowel dysfunction.

Selection criteria for selective dorsal rhizotomy in children with spastic cerebral palsy: a systematic review of the literature

AIM

Information regarding the selection procedure for selective dorsal rhizotomy (SDR) in children with spastic cerebral palsy (CP) is scarce. Therefore, the aim of this study was to summarize the selection criteria for SDR in children with spastic CP.

METHOD

A systematic review was carried out using the following databases: MEDLINE, CINAHL, EMBASE, PEDro, and the Cochrane Library. Additional studies were identified in the reference lists. Search terms included 'selective dorsal rhizotomy', 'functional posterior rhizotomy', 'selective posterior rhizotomy', and 'cerebral palsy'. Studies were selected if they studied mainly children (<18y of age) with spastic CP, if they had an intervention of SDR, if they had a detailed description of the selection criteria, and if they were in English. The levels of evidence, conduct of studies, and selection criteria for SDR were scored.

RESULTS

Fifty-two studies were included. Selection criteria were reported in 16 International Classification of Functioning, Disability and Health model domains including 'body structure and function' (details concerning spasticity [94%], other movement abnormalities [62%], and strength [54%]), 'activity' (gross motor function [27%]), and 'personal and environmental factors' (age [44%], diagnosis [50%], motivation [31%], previous surgery [21%], and follow-up therapy [31%]). Most selection criteria were not based on standardized measurements.

INTERPRETATION

Selection criteria for SDR vary considerably. Future studies should describe clearly the selection procedure. International meetings of experts should develop more uniform consensus guidelines, which could form the basis for selecting candidates for SDR.