Dorsal rhizotomy for children with spastic diplegia of cerebral palsy origin: usefulness of intraoperative monitoring

Selective Dorsal Rhizotomy for Spastic Cerebral Palsy: Report of 18 Cases Performed in the North of Vietnam

OBJECTIVE

The purpose of this report is to describe a case series of children undergoing selective dorsal rhizotomy (SDR) for the treatment of spastic cerebral palsy in Vietnam. Also described is an international cooperation model to facilitate the development of a new, multidisciplinary team for the evaluation and treatment of these children.

METHODS

Details of international collaboration are described, including in-person travel and virtual interactions. All cases of children younger than 18 years undergoing SDR for treatment of spastic cerebral palsy at a single center in Hanoi, Vietnam are described, including preoperative evaluation of spasticity and gait as well as results at 6 and 12 months. Results are summarized using descriptive statistics.

RESULTS

Since the beginning of cooperation in training and transferring SDR techniques by experts from the United States, in the period from June 2016 to December 2022, 18 SDR surgeries were performed in Hanoi. Patients' ages ranged from 2 to 14 years; 13 were male and 5 were female. Overall, approximately 60% of nerve rootlets were cut. Modified Ashworth Scale scores at 6 and 12 months after surgery in the hip, knee, and ankle joints showed improvement from preoperative values. There were 2 recorded complications: intracranial hypotension causing subdural hemorrhage and a case of skin infection at the incision site.

CONCLUSIONS

The ongoing international cooperation between Vietnamese and American physicians has helped improve the surgical treatment of spasticity in children with cerebral palsy in Hanoi, providing children with a surgical treatment option with successful outcomes.

Postoperative outcomes and stimulation responses for sectioned nerve roots during selective dorsal rhizotomy in cerebral palsy

BACKGROUND

Cerebral palsy (CP) is the most cause of motor dysfunction in children. Selective dorsal rhizotomy (SDR) plays a major role in long term spasticity control. However, limited data exists on the effect of SDR on postoperative spasticity treatment requirements and supraspinal effects, and the stimulation responses of dorsal nerve roots in those with CP.

METHODS

The current study included the outcome for 35 individuals undergoing SDR for motor functional outcome, spasticity, baclofen dose changes, botulinum toxin injection frequency, and spasticity related orthopedic procedures. We also report on the stimulation responses in 112 individuals who underwent SDR at our institution.

RESULTS

There was a significant difference in gross motor function measures (GMFM)-66 scores at last follow up that remained present when considering only ambulatory children but not with non-ambulatory children. Ashworth scores were significantly decreased for both upper and lower extremities after SDR at all follow up points. There was a significant decrease in Baclofen dose and botulinum toxin injections requirements after SDR, but no significant difference in the need for orthopedic intervention. A total of 5502 dorsal nerve roots were tested showing a decrease in stimulation intensity and increase in grade on the right side and for descending lumbosacral levels.

CONCLUSIONS

SDR improves gross motor scores during short term follow up but has additional benefits in decreasing baclofen dosing and botulinum toxin injections requirements after surgery. They stimulation responses of sectioned dorsal nerve roots adds to the limited available data and our understanding of the pathological changes that occur in CP.

Selective dorsal rhizotomy: Analysis of two rootlet sectioning techniques

OBJECTIVE

To analyze and compare the efficacy of two selective dorsal rhizotomy (SDR) techniques with intraoperative neurophysiological monitoring, using instrumented three-dimensional gait analysis.

INTRODUCTION

SDR is a common, irreversible surgical treatment increasingly used to address gait disturbances in children with chronic non-progressive encephalopathy by reducing spasticity. Various techniques have been used, which mainly differ in the percentage of rootlets selected for sectioning. A greater proportion of rootlets sectioned leads to a more effective reduction of spasticity; however, there is a potential risk of unwanted neurological effects resulting from excessive deafferentation. While there is evidence of the short- and long-term benefits and complications of SDR, no studies have compared the effectiveness of each technique regarding gait function and preservation of the force-generating capacity of the muscles.

MATERIALS AND METHODS

Instrumented three-dimensional gait analysis was used to evaluate two groups of patients with spastic cerebral palsy treated by the same neurosurgeon in different time periods, initially using a classic technique (cutting 50% of the nerve rootlets) and subsequently a conservative technique (cutting no more than 33% the nerve rootlets).

RESULTS

In addition to an increase in knee joint range of motion (ROM), in children who underwent SDR with the conservative technique, a statistically significant increase (p = 0.04) in the net joint power developed by the ankle was observed. Patients who underwent SDR with the conservative technique developed a maximum net ankle joint power of 1.37 ± 0.61 (unit: W/BW), whereas those who were operated with the classic technique developed a maximum net ankle joint power of 0.98 ± 0.18 (unit: W/BW). The conservative group not only showed greater improvement in net ankle joint power but also demonstrated more significant enhancements in minimum knee flexion during the stance phase and knee extension at initial contact.

CONCLUSION

Our results show that both techniques led to a reduction in spasticity with a positive impact on the gait pattern. In addition, patients treated with the conservative technique were able to develop greater net ankle joint power, leading to a better scenario for rehabilitation and subsequent gait.

Modified Selective Dorsal Rhizotomy Exposure Method for Adults With Spastic Paralysis of the Lower Limbs

BACKGROUND AND OBJECTIVES

Spinal deformities are a common complication after selective dorsal rhizotomy (SDR). In this article, we introduce a more minimally invasive SDR procedure in adult patients with spastic paralysis of the lower limbs.

METHODS

In this retrospective analysis of SDR in 8 adult patients with spastic paralysis of the lower limbs, a modified exposure method was used during the surgery. Only the lower part of the L1 spinous process, upper part of the L2 spinous process, and part of the lamina were resected through L1-2 interlaminar approaches. The motor and sensory roots were found to be completely dependent on electrophysiological monitoring. The sensory roots of the target muscle groups were partially transected. All patients were followed up for 2-4 years. The degree of lower extremity spasm was assessed using the Gross Motor Function Classification Scale, Ashworth grading, Gross Motor Function Measure-66, joint range of motion, and electromyography analysis.

RESULTS

All 8 patients were successfully operated with the help of intraoperative electrophysiological monitoring. The Ashworth score of the target muscles, Gross Motor Function Measure-66 score, and range of motion of the joints improved significantly after surgery. Two patients achieved cross-grade improvement in their Gross Motor Function Classification Scale scores. No persistent incision pain or spinal deformities were observed during follow-up.

CONCLUSION

The interspinous process approach provides sufficient surgical space and reduced the damage to the bone structure of the spine. The electrophysiological monitoring protocol is suitable for adult patients with lower extremity spasm.

Excitability of the radiculo-medullary circuitry in spastic cerebral palsy: An intraoperative neurophysiological study in children undergoing selective dorsal rhizotomy

AIM

To explore - through intraoperative neurophysiology mapping and recordings - the comparative distribution of the reflexive excitability of the L2 to S2 radiculo-metameric segments of the spinal cord in a series of children with bilateral spastic cerebral palsy (CP) who underwent selective dorsal rhizotomy (SDR).

METHOD

Our series included 46 consecutive children (36 males, 10 females; aged 5-16 years, mean 8 years) who underwent SDR, using keyhole interlaminar dorsal rhizotomy. The procedure allowed access to all L2 to S2 roots independently, while preserving the posterior architecture of the lumbar spine. Dorsal roots were stimulated selectively to test reflexive excitability of the corresponding radiculo-metameric levels. Stimulation parameters were identical for all roots for optimal comparison between root levels, with an intensity just above threshold to avoid excessive diffusion. The responses in the main muscular groups in each lower limb were clinically observed and electromyograms recorded. Degrees of excitability were quantified according to Fasano's scale.

RESULTS

The difference between root levels was highly significant. Median values of excitability were 1, 2, 3, 3, 3, and 3 for the L2, L3, L4, L5, S1, and S2 levels respectively. Lower root levels exhibited significantly more excitability.

INTERPRETATION

In addition to insight into the spasticity of children with CP, the profile of segmental excitability can be useful in establishing surgical planning when programming SDR.

WHAT THIS PAPER ADDS

Keyhole interlaminar dorsal rhizotomy modality allowed selective stimulation of all L2-S2 dorsal roots for testing excitability. There were significant differences in reflexive excitability of L2-S2 radiculo-medullary segments. Lower segments of L2-S2 medullary levels have higher excitability. Interindividual variability in excitability of lumbosacral segments justifies intraoperative neurophysiology. This original article is commented on by Young on pages 9-10 of this issue.

Effect of physical training on motor function of ambulant children with diplegia after selective dorsal rhizotomy: A randomized controlled study

BACKGROUND

Children with spastic diplegia experience tonicity, lack of selective motor control, subnormal postural stability and delayed motor development. Selective dorsal rhizotomy followed by physical therapy is a permanent procedure aimed to alleviate hypertonicity.

OBJECTIVE

To explore the efficacy of selective dorsal rhizotomy (SDR) followed by a physical training on gross motor function (GMF), functional balance, walking capacity, selective motor control (SMC) and energy cost of walking (ECW) of ambulant children with spastic diplegia.

METHODS

Forty-two children with spastic diplegia aged 5 to 8 years were randomly assigned into the control or SDR-group. Both groups received a designed physical training of progressive functional strength training and standard orthotic management (SOM) 3 times a week for 6 months. GMF, functional balance, ECW, functional capacity and SMC were assessed by gross motor function measure (GMfM-88), pediatric balance scale (PBS), energy expenditure index (EEI), six-minute walking test (6MWT) and selective control assessment of lower extremity (SCALE), respectively. Assessment was carried out before the treatment (baseline), after 6 months (post I) and 1-year follow-up (post II).

RESULTS

From baseline to post I and post II assessments, changes of GMF, functional balance, ECW, functional capacity and SMC within the control and SDR groups showed significant improvements (P < 0.001). Moreover, group comparison showed significant differences in favor of the SDR group.

CONCLUSION

Integrated physical training followed SDR demonstrated qualitative changes and enhancement in motor function, achieved by spasticity reduction.

Dorsal rhizotomy in cerebral palsy: how root sectioning is influenced by intraoperative neuromonitoring

INTRODUCTION AND OBJECTIVE

Dorsal rhizotomy is a controversial procedure for treating spasticity in children with cerebral palsy, particularly regarding the influence of intraoperative neuromonitoring (ION). The objective of this study was to evaluate the influence of ION in adjusting root sectioning compared the preoperative program established by the multidisciplinary team.

MATERIAL AND METHODS

Twenty-four consecutive children with spastic diplegia or quadriplegia, operated on between 2017 and 2020 in the University Hospital of Nancy, France, were studied. All underwent the same procedure: Keyhole Intralaminar Dorsal rhizotomy (KIDr) with enlarged multilevel interlaminar openings to access all roots from L2 to S2. The Ventral Root (VR) was stimulated to map radicular myotomes, and the Dorsal Root (DR) to test excitability of the segmental circuitry. Muscle responses were observed independently by the physiotherapist and by EMG-recordings. The study compared final root sectioning per radicular level and per side after ION versus the preoperative program determined by the multidisciplinary team.

RESULTS

ION resulted in significant differences in final percentage root sectioning (p<0.05), with a decrease for L2 and L3 and an increase for L5. ION modified the symmetry of sectioning, with 32% instead of 5% in preoperative program. Only 5 children showed change in GMFC score 6 months after surgery.

CONCLUSION

The use of ION during dorsal rhizotomy led to important modifications of root sectioning during surgery, which justifies individual control of each root, level by level and side by side, to optimize the therapeutic effect.

Motor and functional outcome of selective dorsal rhizotomy in children with spastic diplegia at 12 and 24 months of follow-up

Background

Selective dorsal rhizotomy (SDR) in ambulatory children affected by cerebral palsy (CP) is a surgical treatment option to lower spasticity and thereby improve gait and ambulation. The aim of the current study is to investigate the outcome of children with respect to spasticity, muscle strength, and overall function after SDR.

Methods

All children who underwent SDR via a single-level laminotomy in the time period from January 2007 to April 2015 at our center were enrolled in this study. Within a standardized evaluation process, the following was assessed routinely pre-operatively and 12 and 24 months following surgery: extent of spasticity at hip adductors and hamstrings as characterized by the Modified Ashworth Scale (MAS), maximal muscle strength as characterized by the Medical Council Research Scale (MRC), overall function regarding ambulation as characterized by the Gross Motors Function Classification System (GFMCS), and overall function as characterized by the Gross Motor Function Measure (GMFM-88).

Results

Matching sets of pre- and post-operative assessments of the chosen outcome parameters were available for 109 of the 150 children who underwent SDR within the observation period. After 24 months, the MAS scores of hip adductors (n = 59) improved in 71% and 76% of children on the right and left side, respectively. In 20% and 19%, it remained unchanged and worsened in 9% and 5% of children on the right and left side, respectively (p < 0.00625). For hamstrings, the rates for the right and left sides were 81% and 79% improvement, 16% and 16% unchanged, and 4% and 5% worsened, respectively (p < 0.00625). Muscle strength of ankle dorsiflexion and knee extension significantly improved after 24 months. Overall function assessed by GMFM-88 improved significantly by 4% after 12 months (n = 77) and by 7% after 24 months (n = 56, p < 0.0001).

Conclusions

The presented data underlines the benefit of SDR in a pediatric patient collective with bilateral spastic CP. The procedure resulted in an effective and permanent reduction of spasticity and improved overall function without causing relevant weakness of the lower extremities.

How I do it: Selective dorsal rhizotomy, using interlaminar approaches, for spastic diplegia/quadriplegia in children with cerebral palsy

BACKGROUND

Dorsal rhizotomy is considered the gold standard for treating spastic diplegia/quadriplegia in children with cerebral palsy, when rehabilitation programs reveal insufficient to control excess of spasticity.

METHOD

The Keyhole Interlaminar Dorsal rhizotomy modality has been developed to access-individually-all L2-S2 roots, intradurally at the corresponding dural sheath, and preserve the posterior spine architecture. Intraoperative neuromonitoring consists of stimulating each ventral root, to verify its myotomal innervation, and dorsal roots, to explore their reflexive muscular responses in order to help determination of the proportion of rootlets to be cut.

CONCLUSION

This modality, which requires 5 ± 1 h duration, offers tailored accuracy.

Surgical Results of Selective Dorsal Rhizotomy for the Treatment of Spastic Cerebral Palsy

Background

Selective dorsal rhizotomy (SDR) is one of the surgical alternatives for treating spasticity, especially in children with spastic diplegia secondary to cerebral palsy (CP). It is becoming increasingly used, and the results of this operation need to be further highlighted.

Aim

The main objective of this article was to present the results of such surgical procedure in a cohort of a specialized center, with a particular focus on a quantitative analysis (goniometry).

Materials and Methods

Retrospective review of the medical records and gait analyses of a cohort of 34 patients diagnosed with CP submitted to elective SDR at our institution, in a period of 6 years, was carried out. All patients underwent a thorough clinical and neurological assessment, gait analysis at a dedicated laboratory, and magnetic resonance imaging of whole neuro-axis.

Statistical Analysis

For continuous quantitative variables (goniometric angles and muscle tone), a t-student test was used. A scatterplot regression analysis was used for the comparison of modified Ashworth scale (mAS) scores and goniometry measurements.

Results and Conclusion

In a mean follow-up of 3.2 years, SDR provides a measurable and consistent improvement in the motor function of spastic patients, as per range of motion and tonus scales, with low complication rates. It also allows for patients to reduce their use of muscle relaxants, even though their global mobility does not change significantly. Therefore, it should be considered for CP patients who suffer with the deleterious effects of spasticity.

Usefulness of external anal sphincter EMG recording for intraoperative neuromonitoring of the sacral roots-a prospective study in dorsal rhizotomy

BACKGROUND

In conus medullaris and cauda equina surgery, identification of the sacral nerve roots may be uncertain in spite of their anatomical/radiological landmarks. Mapping the sacral roots by recording the muscular responses to their stimulation may benefit from EMG recording of the External Anal sphincter (EAS) in addition to the main muscular groups of the lower limbs.

METHOD

In a consecutive series of 27 lumbosacral dorsal rhizotomy (DRh), authors carried out a prospective study on the reliability of the EMG recording of the EAS for identification of the S1 and S2 sacral roots.

RESULTS

An EAS-response was recorded in all the 27 (bilaterally) explored individuals, testifying good sensitivity and selectivity of the method. EAS-responses were obtained in 96.3% of the 54 stimulated sides of the S2 root versus in only 16.66% for the S1 root, so that an absence of response would indicate S1 rather than S2 level. Furthermore, comparison between myotomal distribution of the S1 and S2 roots showed a significant difference (p < 0.00001), so that myotomal profile may help to identify root level.

CONCLUSIONS

EMG recording of the EAS can be recommended for current intraoperative neuromonitoring. This simple method also provides-indirectly by extrapolation-information on the sacral motor pathways of the external urethral sphincter (EUS), as the later has the same somatic innervation via the pudendal nerve and related S2, S3, and S4 roots. Method can be helpful not only for DRh, of all varieties, but also for spine surgery, correction of dysraphisms, lipomas and/or tethered cord, and tumor resection.

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.

The role of intra-operative neuroelectrophysiological monitoring in single-level approach selective dorsal rhizotomy

OBJECTIVE

Selective dorsal rhizotomy via a single-level approach (SL-SDR) to treat spasticity 100% relies on the interpretation of results from the intra-operative neuroelectrophysiological monitoring. The current study is to investigate the role EMG interpretation plays during SL-SDR procedure with regard to the selection of nerve rootlets for partially sectioning in pediatric cases with spastic cerebral palsy (CP).

METHODS

A retrospective study was conducted in pediatric patients with spastic CP undergone our modified rhizotomy protocol-guided SL-SDR from May 2016 to Mar. 2019 in our hospital. Our study focused on intra-operative EMG interpretation and its correlation with pre-op evaluation results, and dorsal rootlet selection difference when data of our intra-operative EMG recordings interpreted using different rhizotomy protocols.

RESULTS

Clinical and intra-operative neuroelectrophysiological monitoring data of a total of 318 consecutive cases were reviewed, which include 231 boys and 87 girls with 32 hemiplegias, 161 diplegias, and 125 quadriplegias. Age at the time of SL-SDR in those cases was between 3.0-14.0 (5.9 ± 1.9) years. The number of targeted muscle ranged from 2 to 8 over these cases (the muscle in lower limbs with its pre-op muscle tone ≥ 2 grade, Modified Ashworth scale). Among 21,728 nerve rootlets tested (68.3 ± 8.2/case), 6272 (28.9%) were identified sphincter related by our intra-operative neuromonitoring. In the rest of 15,456 (48.6 ± 7.6/case) nerve rootlets which neuromonitoring suggested associated with lower limbs, 11,009 were taken as the dorsal ones (34.6 ± 7.4/case). A total of 3370 (10.6 ± 4.7/case) rootlets matched our rhizotomy criteria with 3061 (9.6 ± 4.1/case) sectioned 50% and 309 (1.0 ± 1.0/case) cut 75%. The rhizotomy ratio (partially transected nerve rootlets/all dorsal rootlets associated with lower limbs in a particular case) was 15.8%, 22.3%, 33.4%, 41.8%, and 45.7% across cases with their pro-op GMFCS level from I to V, respectively. Rootlets required 75% cut had a tendency to increase as well in our cases with their pro-op GMFCS level from I to V, which comprising 1.5%, 4.8%, 8.5%, 14.1%, and 15.2% of all rootlets transected, respectively. The muscle tone of 2068 targeted muscles in these cases at the time of 3 weeks after the SL-SDR was revealed a significant decrease when compared to pre-op (1.7 ± 0.5 vs. 2.7 ± 0.6). Further investigation to compare our rootlet selection with the one guided by the traditional rhizotomy criteria using our intro-operative EMG recordings in 318 cases, revealed that the overlap ratio had a tendency to increase in cases when their pre-op GMFCS level increased (39.5%, 41.3%, 52.2%, 54.1%, and 62.8% in cases with levels I-V, respectively). While our modified rhizotomy protocol successfully identified 2-23 rootlets for sectioning in all of our 318 cases, the traditional rhizotomy protocol failed to distinguish any for cutting in about 20% of cases with their pre-op GMFCS levels I and II.

CONCLUSIONS

The rhizotomy criteria fully rely on the EMG interpretation making intra-operative neuroelectrophysiological monitoring crucial when SDR is performed via a single-level approach. Our modified rhizotomy protocol is feasible, safe, and effective to guide SL-SDR to treat all types of spastic CP cases by decreasing muscle tone in particular spastic muscle groups in their lower limbs. Data of EMG responses during SL-SDR procedure and as well as the clinical outcomes based on their interpretation could help clinicians to further understand how neuronal circuits work in the spinal cord of these patients.

Neurophysiological mechanisms of hypertonia and hypotonia in children with spastic cerebral palsy: surgical implications

Mechanism of hypertonia in cerebral palsy children is dual: a neural component due to spasticity (velocity dependent) and a biomechanical component linked to soft tissue changes. Their differentiation-which might be clinically difficult-is however crucial, as only the first component will respond to anti-spastic treatments, the second to physiotherapy. Furthermore, spasticity is frequently associated with dystonia, which is a sustained hypertonic state induced by attempts at voluntary motion. Spasticity and dystonia have to be carefully distinguished as dorsal rhizotomy will not significantly influence the dystonic component. Spasticity, which by definition opposes to muscle stretching and lengthening, has two important consequences. First, the muscles tend to remain in a shortened position, which in turn results in soft tissue changes and contracture. The second is that movements are restricted. Thus, both hypertonia and lack of mobilization create a vicious circle leading to severe locomotor disability linked to irreducible musculotendinous retraction and joint ankylosis/bone deformities. These evolving consequences should be highly considered during the child's assessment for decision-making. The hypotonic effects of lumbosacral dorsal rhizotomy, which are not only segmental on the lower limbs but also supra-segmental through the reticular formation, are finally discussed.

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.

Muscle responses to radicular stimulation during lumbo-sacral dorsal rhizotomy for spastic diplegia: Insights to myotome innervation

OBJECTIVE

Most of knowledge on muscle radicular innervation was from explorations in root/spinal cord pathologies. Direct and individual access to each of the lumbar-sacral -ventral and dorsal- nerve roots during dorsal rhizotomy for spastic diplegia allows precise study of the corresponding muscle innervation. Authors report the lumbo-sacral segmental myotomal organization obtained from recordings of muscle responses to root stimulation in a 20-children prospective series.

METHODS

Seven key-muscles in each lower limb and anal sphincter were Electromyography (EMG)-recorded and clinically observed by physiotherapist during L2-to-S2 dorsal rhizotomy. Ventral roots (VR), for topographical mapping, and dorsal roots (DR), for segmental excitability testing, were stimulated, just above threshold for eliciting muscular response.

RESULTS

In 70% of the muscles studied, VR innervation was pluri-radicular, from 2-to-4 roots, with 1 or 2 roots being dominant at each level. Overlapping was important. Muscle responses to DR stimulation were 1.75 times more extended compared to VR stimulation. Inter-individual variability was important.

CONCLUSIONS

Accuracy of root identification and stimulation with the used method brings some more precise information to radicular functional anatomy.

SIGNIFICANCE

Those neurophysiological findings plead for performing Intra-Operative Neuromonitoring when dealing with surgery in the lumbar-sacral roots.

Feasibility and effectiveness of a newly modified protocol-guided selective dorsal rhizotomy via single-level approach to treat spastic hemiplegia in pediatric cases with cerebral palsy

PURPOSE

It still remains challenging to treat CP cases with spastic hemiplegia using SDR via a single-level approach when guided by the traditional EMG response grading system. Our aim was to assess the feasibility and effectiveness of a newly modified protocol-guided single-level laminectomy SDR to treat such pediatric patients.

METHODS

A retrospective cohort review was conducted in the CP cases with spastic hemiplegia undergone our newly modified protocol-guided single-level approach SDR since May 2016 to October 2017, and followed by intensive rehabilitation program for at least 12 months in both Shanghai Children's Hospital and Shanghai Rehabilitation and Vocational Training Center for the Disabled. Inclusion and exclusion criteria were set for the selection of patients in the current study. Our study focused on the setup, EMG recording interpretation, and outcome measures for this newly modified rhizotomy scheme.

RESULTS

Eleven cases were included in the current study. Based on our new rhizotomy protocol, a total of 34 rootlets over our 11 cases were cut (2 in 4, 3 in 4, 4 in 1, and 5 rootlets in 2 cases, respectively). After SDR and the following rehabilitation program at a mean duration of 19 months, muscle tone of those "target muscles" in affected lower extremities which identified during pre-op assessment decreased by a mean of 1.4 degrees (Modified Ashworth Scale) in our cases. Strength of those target muscles and ROM of joints involved in their lower limbs were reported to have improved significantly as well. All cases showed major progress with regard to their motor function. A mean of about 10-point increase of GMFM-66 score was reported, and five of six cases who were with GMFCS level II preoperatively improved their GMFCS level at the last assessment. Kinematics of joints of hip, knee, and ankle on the affected side in our cases demonstrated a major correction, along with improvement of their foot pressure patterns to the ground during their gait cycles. Surgery-related complications, such as cerebral-spinal fluid leak/infection, long-term hypoesthesia, or urinary/bowel incontinence were not recorded in the current study.

CONCLUSION

Single-level SDR when guided by our simplified rhizotomy protocol is feasible and effective to treat pediatric CP cases with spastic hemiplegia.

Feasibility of intraoperative monitoring of motor evoked potentials obtained through transcranial electrical stimulation in infants younger than 3 months

OBJECTIVE

This study aimed to investigate the feasibility and safety of intraoperative motor evoked potential (MEP) monitoring in infants less than 3 months of age.

METHODS

The authors investigated 25 cases in which infants younger than 3 months (mean age 72.8 days, range 39-87) underwent neurosurgery between 2014 and 2017. Myogenic MEPs were obtained through transcranial electrical stimulation. In all cases, surgery was performed under total intravenous anesthesia, maintained with remifentanil and propofol.

RESULTS

MEPs were documented in 24 infants, the sole exception being 1 infant who was lethargic and had 4-limb weakness before surgery. The mean stimulation intensity maintained during monitoring was 596 ± 154 V (range 290-900 V). In 19 of 24 infants MEP signals remained at ≥ 50% of the baseline amplitude throughout the operation. Among 5 cases with a decrease in intraoperative MEP amplitude, the MEP signal was recovered in one during surgery, and in the other case a neurological examination could not be performed after surgery. In the other 3 cases, 2 infants had relevant postoperative weakness and the other did not show postoperative neurological deficits. Postoperative weakness was not observed in any of the 20 infants who had no deterioration (n = 19) or only temporary deterioration (n = 1) in MEP signal during surgery.

CONCLUSIONS

Transcranial electrical MEPs could be implemented during neurosurgery in infants between 1 and 3 months of age. Intraoperative MEP monitoring may be a safe adjunct for neurosurgical procedures in these very young patients.

The Evolution of Selective Dorsal Rhizotomy for the Management of Spasticity

Selective dorsal rhizotomy is a key technique in the surgical management of spasticity in patients with cerebral palsy. The technique evolved from the late 1800s when pioneers like Dana and Abbe performed dorsal rhizotomy in their treatment of refractory pain. These surgeons noted a reduction in muscle tone associated with the operation. When Sherrington then published his Nobel prize-winning work on the corticospinal tract and its role in the neuromuscular system in the 1890s, the course was set for modifying spasticity by aiming surgery at the dorsal roots. This procedure underwent multiple modifications through the next century and today it is, arguably, the most commonly performed operation to treat cerebral palsy children with spasticity. Selective dorsal rhizotomy is a technique that still teaches us a great deal about neurophysiology on a daily basis and it is thanks to the pioneers, described in this article, that we have this tool in our armamentarium.