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

Authors:
Marc P Sindou at Hospices Civils de Lyon (Centre Hospitalier Universitaire de Lyon)
Marc P Sindou
Anthony Joud
Anthony Joud
Anthony Joud
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G. Georgoulis at CHU de Lyon - Hôpital Neurologique et Neurochirurgical Pierre Wertheimer
G. Georgoulis
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Abstract and Figures

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.
Principle of the Keyhole Interlaminar Dorsal rhizotomy (KIDr) operation. Left: Schematic drawing of the interlaminar (IL) vertebral levels where the (L2 to S2) lumbo-sacral roots can be targeted. At each of the (three) fenestrated levels, the inferior two-thirds of the upper lamina and the superior three-fourths of the lower lamina are rongered and flavum ligament removed, so that the dura and arachnoid are opened on midline. L2 and L3 roots can be acceded at L1–L2, L4 and L5 at L3–L4, S1 and S2 at L5–S1 (enlarged) interspaces. Right: Postoperative (anterior-posterior) X-ray of the lumbar spine showing the three enlarged IL fenestrations, with preservation of the spinous processes
Principle of the Keyhole Interlaminar Dorsal rhizotomy (KIDr) operation. Left: Schematic drawing of the interlaminar (IL) vertebral levels where the (L2 to S2) lumbo-sacral roots can be targeted. At each of the (three) fenestrated levels, the inferior two-thirds of the upper lamina and the superior three-fourths of the lower lamina are rongered and flavum ligament removed, so that the dura and arachnoid are opened on midline. L2 and L3 roots can be acceded at L1–L2, L4 and L5 at L3–L4, S1 and S2 at L5–S1 (enlarged) interspaces. Right: Postoperative (anterior-posterior) X-ray of the lumbar spine showing the three enlarged IL fenestrations, with preservation of the spinous processes
… 
Operating room set-up and surgical steps. a–c Patient is in a prone position, head 10 cm lower to minimize CSF depletion. Surgeon is located so that roots be accessed contralaterally, passing obliquely underneath the interspinous ligament. A microscope is placed in order to be rotated from one side to the other. d The physical therapist should have an optimal access to the patient’s legs for clinical checking of the muscle responses. EMG responses are recorded from bipolar needle–electrodes implanted in adductors (for L2–L3 roots), quadriceps (for L3–L4), tibialis anterioris (for L4), extensor digitorum (for L5), soleus (for S1), biceps femoris (for S1–S2), flexor digitorum (for S2), anal sphincter (for S2–S3–S4). e Exposure of L1–S1 laminae, with L1–L2, L3–L4, and L5–S1 interlaminar (IL) fenestrations. Surgeon’s trajectory will pass underneath the interspinous ligament (“keyhole” surgery) to access the contralateral root(s)—in this example, the L4 (and L5) root(s), on the right side, at the L3–L4 interspace (arrow). f1,2,3,4 ( from top to bottom): opening of dura on midline at L3-L4 interspace (f1); dura suspended (f2); access to (right) L4 root and stimulation; root L5 is visible (f3); (partial) sectioning of the L4 dorsal root (f4)
Operating room set-up and surgical steps. a–c Patient is in a prone position, head 10 cm lower to minimize CSF depletion. Surgeon is located so that roots be accessed contralaterally, passing obliquely underneath the interspinous ligament. A microscope is placed in order to be rotated from one side to the other. d The physical therapist should have an optimal access to the patient’s legs for clinical checking of the muscle responses. EMG responses are recorded from bipolar needle–electrodes implanted in adductors (for L2–L3 roots), quadriceps (for L3–L4), tibialis anterioris (for L4), extensor digitorum (for L5), soleus (for S1), biceps femoris (for S1–S2), flexor digitorum (for S2), anal sphincter (for S2–S3–S4). e Exposure of L1–S1 laminae, with L1–L2, L3–L4, and L5–S1 interlaminar (IL) fenestrations. Surgeon’s trajectory will pass underneath the interspinous ligament (“keyhole” surgery) to access the contralateral root(s)—in this example, the L4 (and L5) root(s), on the right side, at the L3–L4 interspace (arrow). f1,2,3,4 ( from top to bottom): opening of dura on midline at L3-L4 interspace (f1); dura suspended (f2); access to (right) L4 root and stimulation; root L5 is visible (f3); (partial) sectioning of the L4 dorsal root (f4)
… 
Intra-operative neuro-monitoring. Example of ION at the (right) L4 root under its keyhole approach. Free-running recordings of compound motor action potentials on the “paused” monitoring screen. X-axis represents the duration in milliseconds (from 0 to 600 ms) and Y-axis the amplitude in microvolt (from - 250 to 250 μV). Anatomical mapping (upper row): After exposure and individualization of the ventral and dorsal roots at exit to/entry from the dural sheath, ventral root is stimulated using a bipolar electrode muscle responses are in the quadriceps and to a lesser extent the Adductors muscular groups. Physiological testing (lower row): The aim is to estimate the degree of excitability of the various segmental radicular-spinal circuitry. Dorsal root stimulation elicits abnormal EMG responses of grade 3 according to Fasano’s classification. Grade 3 corresponds to sustained (i.e., lasting after cessation of stimulation) muscle responses, not only at the level of the (L4) myotome (= muscles responding to ventral stimulation) but also spreading to distant myotomes
Intra-operative neuro-monitoring. Example of ION at the (right) L4 root under its keyhole approach. Free-running recordings of compound motor action potentials on the “paused” monitoring screen. X-axis represents the duration in milliseconds (from 0 to 600 ms) and Y-axis the amplitude in microvolt (from - 250 to 250 μV). Anatomical mapping (upper row): After exposure and individualization of the ventral and dorsal roots at exit to/entry from the dural sheath, ventral root is stimulated using a bipolar electrode muscle responses are in the quadriceps and to a lesser extent the Adductors muscular groups. Physiological testing (lower row): The aim is to estimate the degree of excitability of the various segmental radicular-spinal circuitry. Dorsal root stimulation elicits abnormal EMG responses of grade 3 according to Fasano’s classification. Grade 3 corresponds to sustained (i.e., lasting after cessation of stimulation) muscle responses, not only at the level of the (L4) myotome (= muscles responding to ventral stimulation) but also spreading to distant myotomes
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Example of form to be filled during ION from clinical observation and EMG recordings
Example of form to be filled during ION from clinical observation and EMG recordings
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Fasano’s classification for estimation of the degree of spasticity in spastic diplegic children affected with cerebral palsy (MR, muscle response; DR, dorsal root)
+1
Fasano’s classification for estimation of the degree of spasticity in spastic diplegic children affected with cerebral palsy (MR, muscle response; DR, dorsal root)
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HOW I DO IT - FUNCTIONAL NEUROSURGERY - OTHER
How I do it: Selective dorsal rhizotomy, using
interlaminar approaches, for spastic diplegia/quadriplegia in children
with cerebral palsy
Marc Sindou
1,2,3
&Anthony Joud
2,3
&George Georgoulis
4,5
Received: 21 January 2021 / Accepted: 11 February 2021
#The Author(s), under exclusive licence to Springer-Verlag GmbH, AT part of Springer Nature 2021
Abstract
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.
Keywords Cerebral palsy .Dorsal rhizotomy .Intraoperative neuromonitoring .Pediatric rehabilitation .Selective dorsal
rhizotomy .Spasticity
Relevant surgical anatomy
This newly developed modality of dorsal rhizotomy,
named “Keyhole Interlaminar Dorsal rhizotomy
(KIDr)”—keyhole at levels between two vertebrae [9]—
has two objectives.
1. Individual intradural access to all of the L2-S2 lumbo-
sacral roots at the corresponding foraminal dural
sheath, where the ventral (=motor) and dorsal (=sen-
sory) components are distinguishable, allows their ac-
curate topographic identification. Proper myotomal
distribution can be verified using electrical stimula-
tion of their ventral component [6]. This corresponds
to “anatomical mapping”(Fig. 1).
There also, the degree of reflective excitability of the
various medullary segments can be evaluated by stimula-
tion of the dorsal component.This“physiological test-
ing,”by estimating the implication of each radicular level
in the harmful components of the spasticity, provides an
objective help to quantify sectioning [5].
2. The second objective is to respect the posterior architec-
ture of the lumbo-sacral spine, by only performing inter-
laminar (IL) fenestrations with preservation of the spinous
processes and interspinous ligaments, so as to minimize
the risk of secondary instability. [12]
Levels and number of IL approaches, as well as the
quantity of dorsal rootlets to be cut, are determined
according to the patient’s clinical presentation and ob-
jective(s) of the surgery, thus achieving individual “tai-
lored surgery.”
This article is part of the Topical Collection on Functional Neurosurgery
- Other
*George Georgoulis
gdgeorgoulis@gmail.com
1
University of Lyon, Lyon, France
2
IRR Flavigny, UGECAM Nord-Est, Nancy, France
3
Pediatric Neurosurgery Department, CHRU Nancy, Nancy, France
4
Department of Neurosurgery, General Hospital of Athens
“G.Gennimatas”, Mesogeion Avenue 154, 11527 Athens, Greece
5
Medical School, University of Athens, Athens, Greece
https://doi.org/10.1007/s00701-021-04770-x
/ Published online: 24 February 2021
Acta Neurochirurgica (2021) 163:2845–2851
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Lors de la rhizotomie dorsale interlaminaire «single-level» mini-invasive, les lames ne sont réséquées que partiellement ( fig. 2A) afin de prévenir une instabilité secondaire [37]. L'incision d' environ 10-15 mm de long [13,16] est pratiquée sur la ligne médiane de la dure-mère à l'aide d'un microscope [16,27,29,33,35,37]. ...
... 2A) afin de prévenir une instabilité secondaire [37]. L'incision d' environ 10-15 mm de long [13,16] est pratiquée sur la ligne médiane de la dure-mère à l'aide d'un microscope [16,27,29,33,35,37]. Après ouverture de l'arachnoïde, la terminaison du cône ainsi que les fibres de la queue-de-cheval sont visibles. ...
... Après ouverture de l'arachnoïde, la terminaison du cône ainsi que les fibres de la queue-de-cheval sont visibles. La stimulation électrique bipolaire permet de distinguer les fibres nerveuses sensorielles (ventrales) des fibres nerveuses motrices (ventrales) des deux côtés (L2 à S1) ( fig. 2 B) [13,27,29,37,39]. Certaines fibres nerveuses sont d'abord stimulées pendant 0,2 ms [27, 40] à une fréquence de 3 Hz afin de déterminer un seuil d' excitation pour la différentiation (il s'agit de la cartographie anatomique [37]). ...
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... Als zusätzliche intraoperative Kontrolle und Hilfe zur Neurostimulation werden die jeweiligen Kennmuskeln an den Beinen des Kindes von einer Fachperson der Physiotherapie ertastet und bei Kontraktionen der oder dem Operierenden als positive Reaktion gemeldet. Nach Beenden der Rhizotomie wird die Dura mater mittels einer fortlaufenden Naht wasserdicht verschlossen [16,37]. Auch die Muskulatur und die Haut werden vernäht. ...
... 2A)[6].Bei der minimalinvasiven «single-level»inter laminaren dorsalen Rhizotomie werden die Laminae nur partiell entfernt (Abb. 2A), um einer sekundären Instabilität vorzubeugen[37]. Der ungefähr 10-15 mm lange Schnitt[13,16] erfolgt auf der Mittellinie der Dura mater und wird mithilfe eines Mikroskops durchgeführt[16, 27, 29, 33, 35,37]. ...
... 2A), um einer sekundären Instabilität vorzubeugen[37]. Der ungefähr 10-15 mm lange Schnitt[13,16] erfolgt auf der Mittellinie der Dura mater und wird mithilfe eines Mikroskops durchgeführt[16, 27, 29, 33, 35,37]. Nach Eröffnung der Arachnoidea werden das Conus-Ende sowie die Caudaequina-Fasern dargestellt. ...
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... The SDR modality used was the KIDr technique, which we have already presented. 9,10 The purpose was to access all lumbosacral roots individually and stimulate successively their ventral and dorsal components, selectively. At the same time, we preserved the spinous processes and interspinous ligaments to minimize destabilization of the spine, while allowing access to all of the L2 to S2 roots ( Figure 1a). ...
... The spaces to be opened (and enlarged over 20-30 mm in height) are determined according to the plan for root sectioning (tailored operation). 10,11 Centre, postoperative X-ray shows the (enlarged) interlaminar fenestrations with respect to laminae and spinous processes. Two adjacent roots on the same side can be accessed after opening of the dura and arachnoid on the midline: one root upwards, the other downwards. ...
... 14 Despite its 'cost' in terms of surgical duration (5 plus-minus 1 hours), our standardized protocol allows access to all the ventral and dorsal roots individually under precise anatomical landmarks at the foraminal region, and to stimulate all the L2 to S2 roots selectively. 9,10,14 Our study has shown, in all the children's series and for almost all segmental levels, an exaggerated degree of reflexive excitability (Figure 4). This is consistent with the various definitions of spasticity given over time, from the first classic characterization by Lance to the most recent by Sanger and van de Noort, which are the most used in the disciplines of neurology and rehabilitation. ...
Excitability of the radiculo‐medullary circuitry in spastic cerebral palsy: An intraoperative neurophysiological study in children undergoing selective dorsal rhizotomy
Article
Full-text available
  • Jun 2022
  • DEV MED CHILD NEUROL
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.
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... The surgical team is required to differentiate dorsal spinal nerve roots from those ventral ones in the cauda equina as the first step in the selection during such a procedure (3). When SDR is performed under a multi-level (4,5) or a less-traumatic keyhole interlaminar approach (6,7), such differentiation could be achieved by the natural anatomy of those nerve roots at the nerve exit from the dura sac at a certain level (8). The operators could also differentiate nerve roots by comparing their neurophysiological characteristic differences, such as the electrical threshold to elicit electromyography (EMG) responses in monitored muscles (9), with both lower limbs and anal sphincter included (10). ...
Quantitative identification of ventral/dorsal nerves through intraoperative neurophysiological monitoring by supervised machine learning
Article
Full-text available
  • May 2023
Objective This study aimed to investigate the electro-neurophysiological characteristics of the ventral and dorsal nerves at the L2 segment in a quantitative manner. Methods Medical records of consecutive patients who underwent single-level approach selective dorsal rhizotomy (SDR) from June 2019 to January 2022 were retrospectively reviewed. Intraoperative electro-neurophysiological data were analyzed. Results A total of 74 males and 27 females were included in the current study with a mean age of 6.2 years old. Quadriceps and adductors were two main muscle groups innervated by L2 nerve roots in both ventral and dorsal nerve roots. Dorsal roots have a higher threshold than that of the ventral ones, and muscles that first reached 200 µV innervated by dorsal roots have longer latency and smaller compound muscle action potential (CMAP) than those of the ventral ones. Supervised machine learning can efficiently distinguish ventral/dorsal roots using threshold + latency or threshold + CMAP as predictors. Conclusion Electro-neurophysiological parameters could be used to efficiently differentiate ventral/dorsal fibers during SDR.
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... The improved waking ability has a positive impact on the achievement of their daily activities and the motivation of their social engagement, which matters considerably for these patients (19). Additionally, spasticity is the main factor affecting the motor function of children with SCP, which could be relieved by SDR (20). Patients with SCP could improve their motor function after the reduction of spasticity if they keep doing post-operational rehabilitation (4,5). ...
Improvement of the gait pattern after selective dorsal rhizotomy derives from changes of kinematic parameters in the sagittal plane
Article
Full-text available
  • Dec 2022
Objective Selective dorsal rhizotomy (SDR) can decrease spasticity in children suffering from spastic cerebral palsy (SCP) and thus improve their moving ability when supplemented with the post-operational rehabilitation program. In this case, the study aims to investigate the gait changes in children with mild SCP after SDR in short-term follow-up. Methods The information of ambulatory SCP cases who underwent SDR in our center was retrospectively reviewed, and comparisons of changes in spasticity, motor function and data of gait analysis before and after SDR were analyzed. Results In total, 32 cases were included in this study, with a mean age of 5.9 ± 2.1 years old. Noticeable decrease was found in the median value of the pre-operational MAS score after SDR at last follow-up in both sides of adductors, gastrocnemius, soleus, and left hamstrings. The Gross Motor Function Measure-66 score increased from 70.6 ± 9.2 to 73.4 ± 8.2, and the gait deviation index increased after SDR compared with the pre-operational data (right side: 65.8 ± 8.8 vs. 60.1 ± 10.7; left side: 63.5 ± 10.1 vs. 57.0 ± 9.9). Noticeable changes were found that the maximum angle of affected ankles in the sagittal plane (the dorsal-flexion angle) increased from 2.5° to 8.2°, the angles at initial contact (1% gait cycle) of affected knees in the sagittal plane decreased from 34.0° to 27.8°, and the angles at the end of swing phase (100% gait cycle) of affected knees in the sagittal plane decreased from 35.8° to 28.3°. Conclusion In short-term follow-up, SDR can lower spasticity in children with SCP. Post-operational gait analysis showed improvements in gross motor function and gait, which derived from the changes in the sagittal plane (ankle and knee). A longer follow-up duration is thus needed to clarify the long-term outcome.
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Modified Selective Dorsal Rhizotomy Exposure Method for Adults With Spastic Paralysis of the Lower Limbs
Article
  • Dec 2023
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.
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Multidimensional Outcomes of Selective Dorsal Rhizotomy for Children With Spastic Cerebral Palsy: Single-Level Laminectomy vs Multiple-Level Laminotomy Techniques
Article
  • Jun 2022
  • NEUROSURGERY
Background: Selective dorsal rhizotomy (SDR) reduces lower limb spasticity, improves gait patterns, and restores normal physical and social activity in children with spastic cerebral palsy. Single-level laminectomy (SLL) and multiple-level laminotomy (MLL) are 2 surgical approaches for SDR with limited clinical data comparing their postoperative outcomes. Objective: To compare the differences in multidimensional outcomes after SDR between SLL and MLL for children with spastic cerebral palsy. Methods: We retrospectively reviewed children who underwent SDR in our hospital from 1997 to 2016. The multidimensional outcomes in spasticity, joint range of motions, gait kinetics, gross motor activities, functional outcomes, and urological outcomes were assessed 1 year postoperatively. Hip dysplasia and scoliosis rate were compared as long-term outcomes. Results: Sixty children underwent SDR, including 34 SLL patients and 26 MLL patients. Most improvements in multidimensional outcomes were comparable between SLL and MLL. Patients in the SLL group had larger improvements in ankle dorsiflexion in the midstance phase (SLL 7.59° ± 11.48° vs MLL 0.29° ± 11.30°, P = .027). The rate of scoliosis was similar between the 2 surgical approaches (SLL 12.1% vs MLL 15.4%, P = .722). Conclusion: SDR for children with spastic cerebral palsy could provide physical, functional, and urological improvements. SLL achieved a higher degree of improvement in ankle dorsiflexion in the midstance phase. The rate of scoliosis was not significantly increased by multiple-level laminotomy.
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Dorsal Rhizotomy for Children with Cerebral Palsy
Chapter
  • Jun 2022
As soon as the early twentieth century, dorsal rhizotomy (DRh) was known to alleviate spastic hypertonia. But it is only in the last 20 years that DRh became commonly used after refinements in surgical indications and in the selection of roots/rootlets on their topographic and/or functional responses to stimulation. Optimal timing for surgery is considered when spasticity becomes refractory to all conservative treatment and physical therapy, and before irreducible contractures and deformities appear. In children able to ambulate, the realistic goal is to improve gait, walk, and function. In children more severely affected, especially quadriplegic patients, the goal is to increase comfort, decrease pain, ease nursing cares, and diminish the overall emotional overactivity and parasite movements in upper limbs thanks to distant effects.
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Dorsal rhizotomy in cerebral palsy: How root sectioning is influenced by intraoperative neuromonitoring?
Article
  • Feb 2022
  • NEUROCHIRURGIE
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.
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Usefulness of external anal sphincter EMG recording for intraoperative neuromonitoring of the sacral roots—a prospective study in dorsal rhizotomy
Article
Full-text available
  • Feb 2021
  • ACTA NEUROCHIR
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.
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The selective dorsal rhizotomy technique for spasticity in 2020: a review
Article
Full-text available
  • Sep 2020
  • CHILD NERV SYST
This review looks at the advances in the surgical technique, selective dorsal rhizotomy, used for the management of spasticity in children.
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Selective dorsal rhizotomy for spasticity of genetic etiology
Article
Full-text available
  • Jul 2020
  • CHILD NERV SYST
Objective Selective dorsal rhizotomy (SDR) is most commonly applied in the context of the treatment of the spastic diplegic variant of cerebral palsy (CP). Its role in the treatment of spasticity associated with other conditions is not well-established. We sought to review outcomes following SDR for the treatment of functionally limiting spasticity in the setting of a genetic etiology. Methods A systematic literature review was performed using the databases Ovid Medline, Embase, Cochrane Library, and PubMed based on the PRISMA guidelines. Articles were included if they described the application of SDR for spasticity of genetic etiology. Reported outcomes pertaining to spasticity and gross motor function following SDR were summarized. Results Five articles reporting on 16 patients (10 males, 6 females) met the inclusion criteria, of which four reported on SDR for hereditary spastic paraplegia (HSP) and four on syndromic patients or other inherited diseases, with an overall follow-up ranging from 11 to 252 months. These individuals were found to have several genetic mutations including ALS2, SPG4, and SPG3A. The mean age at the time of surgery was 14.9 years (median 10 years, range 3–37 years). Conclusions Although all patients experienced a reduction in spasticity, the long-term gross motor functional outcomes objectively assessed at last follow-up were heterogeneous. There may be a role for SDR in the context of static genetic disorders causing spasticity. Further evidence is required prior to the widespread adoption of SDR for such disorders as, based on the collective observations of this review, spasticity is consistently reduced but the long-term effect on gross motor function remains unclear.
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Selective dorsal rhizotomy for the treatment of severe spastic cerebral palsy: efficacy and therapeutic durability in GMFCS grade IV and V children
Article
Full-text available
  • Apr 2018
  • ACTA NEUROCHIR
Background: Selective dorsal rhizotomy (SDR) has been established as an effective surgical treatment for spastic diplegia. The applicability of SDR to the full spectrum of spastic cerebral palsy and the durability of its therapeutic effects remain under investigation. There are currently limited data in the literature regarding efficacy and outcomes following SDR in Gross Motor Function Classification System (GMFCS) IV and V patients. Intrathecal baclofen has traditionally been the surgical treatment of choice for these patients. When utilised primarily as a treatment for the relief of spasticity, it is proposed that SDR represents a rational and effective treatment option for this patient group. We report our outcomes of SDR performed on children with severe cerebral palsy (GMFCS grade IV and V). The commensurate improvement in upper as well as lower limb spasticity is highlighted. Apparent benefit to urological function following SDR in this patient group is also discussed. Method: A retrospective review of prospectively collected data for 54 paediatric patients with severe cerebral palsy (GMFCS IV-V) who received SDR plus specialised physiotherapy. Mean age was 10.2 years (range, 3.0-19.5). SDR guided by electrophysiological monitoring was performed by a single experienced neurosurgeon. All subjects received equivalent physiotherapy. The primary outcome measure was change to the degree of spasticity following SDR. Spasticity of upper and lower limb muscle groups were quantified and standardised using the Ashworth score. Measures were collected at baseline and at 2-, 8- and 14-month postoperative intervals. In addition, baseline and 6-month postoperative urological function was also evaluated as a secondary outcome measure. Results: The mean lower limb Ashworth score at baseline was 3.2 (range, 0-4). Following SDR, significant reduction in lower limb spasticity scores was observed at 2 months and maintained at 8 and 14 months postoperatively (Wilcoxon rank, p < 0.001). The mean reduction at 2, 8 and 14 months was 3.0, 3.2 and 3.2 points respectively (range, 1-4), confirming a sustained improvement of spasticity over a 1-year period of follow-up. Significant reduction in upper limb spasticity scores following SDR was also observed (mean, 2.9; Wilcoxon rank, p < 0.001). Overall, the improvement to upper and lower limb tone following SDR-generally to post-treatment Ashworth scores of 0-was clinically and statistically significant in GMFCS IV and V patients. Urological assessment identified pre-existing bladder dysfunction in 70% and 90% of GMFCS IV and V patients respectively. Following SDR, improvement in urinary continence was observed in 71% of affected GMFCS IV and 42.8% of GMFCS V patients. No serious postoperative complications were identified. Conclusions: We conclude that SDR is safe and-in combination with physiotherapy-effectively reduces spasticity in GMFCS grade IV and V patients. Our series suggests that spastic quadriplegia is effectively managed with significant improvements in upper limb spasticity that are commensurate with those observed in lower limb muscle groups. These gains are furthermore sustained more than a year postoperatively. In light of these findings, we propose that SDR constitutes an effective treatment option for GMFCS IV and V patients and a rational alternative to intrathecal baclofen.
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Neurosurgical lesioning-procedures for spasticity and focal dystonia
Chapter
  • Jan 2020
When spasticity becomes excessive and aggravates disability, functional neurosurgery can be a recourse. If excess of spasticity is rather diffuse and predominant in both lower limbs, first option is intrathecal baclofen therapy. When hypertonia is rather localized, of purely spastic nature or associated with focal dystonia, lesioning procedures may be indicated, provided being selective due to their irreversibility. Lesioning procedures can be performed at peripheral nerves [when spasticity is focalized and tributary to one or a few peripheral nerve(s)] or lumbosacral dorsal roots (especially for children affected with cerebral palsy at a young age) or spinal cord under the form of myelotomies (for bedridden paraplegic patients) or dorsal root entry zone (DREZ) at cervical segments (for hemiplegic—without or with focal dystonia—upper limb) or at lumbosacral segments (for severely paralyzed paraplegic patients). Whatever modality, lesioning surgery is essentially based on an accurate identification of the motor innervation and/or the reflex-circuitry sustaining muscle tone.
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Muscle responses to radicular stimulation during lumbo-sacral dorsal rhizotomy for spastic diplegia: Insights to myotome innervation
Article
  • Feb 2020
  • CLIN NEUROPHYSIOL
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.
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The Evolution of Selective Dorsal Rhizotomy for the Management of Spasticity
Article
  • Nov 2018
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.
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Dorsal rhizotomy for children with spastic diplegia of cerebral palsy origin: Usefulness of intraoperative monitoring
Article
  • Apr 2018
  • J NEUROSURG-PEDIATR
OBJECTIVE The utility of intraoperative neuromonitoring (ION), namely the study of muscle responses to radicular stimulation, remains controversial. The authors performed a prospective study combining ventral root (VR) stimulation for mapping anatomical levels and dorsal root (DR) stimulation as physiological testing of metameric excitability. The purpose was to evaluate to what extent the intraoperative data led to modifications in the initial decisions for surgical sectioning established by the pediatric multidisciplinary team (i.e., preoperative chart), and thus estimate its practical usefulness. METHODS Thirteen children with spastic diplegia underwent the following surgical protocol. First, a bilateral intradural approach was made to the L2–S2 VRs and DRs at the exit from or entry to their respective dural sheaths, through multilevel interlaminar enlarged openings. Second, stimulation—just above the threshold—of the VR at 2 Hz to establish topography of radicular myotome distribution, and then of the DR at 50 Hz as an excitability test of root circuitry, with independent identification of muscle responses by the physiotherapist and by electromyographic recordings. The study aimed to compare the final amounts of root sectioning—per radicular level, established after intraoperative neuromonitoring guidance—with those determined by the multidisciplinary team in the presurgical chart. RESULTS The use of ION resulted in differences in the final percentage of root sectioning for all root levels. The root levels corresponding to the upper lumbar segments were modestly excitable under DR stimulation, whereas progressively lower root levels displayed higher excitability. The difference between root levels was highly significant, as evaluated by electromyography (p = 0.00004) as well as by the physiotherapist (p = 0.00001). Modifications were decided in 11 of the 13 patients (84%), and the mean absolute difference in the percentage of sectioning quantity per radicular level was 8.4% for L-2 (p = 0.004), 6.4% for L-3 (p = 0.0004), 19.6% for L-4 (p = 0.00003), 16.5% for L-5 (p = 0.00006), and 3.2% for S-1 roots (p = 0.016). Decreases were most frequently decided for roots L-2 and L-3, whereas increases most frequently involved roots L-4 and L-5, with the largest changes in terms of percentage of sectioning. CONCLUSIONS The use of ION during dorsal rhizotomy led to modifications regarding which DRs to section and to what extent. This was especially true for L-4 and L-5 roots, which are known to be involved in antigravity and pelvic stability functions. In this series, ION contributed significantly to further adjust the patient-tailored dorsal rhizotomy procedure to the clinical presentation and the therapeutic goals of each patient.
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Keyhole interlaminar dorsal rhizotomy for spastic diplegia in cerebral palsy
Article
  • May 2015
  • ACTA NEUROCHIR
The efficiency and safety of dorsal rhizotomies for cerebral palsy lie in the accuracy of radicular identification together with selectivity of root sectioning. Two different exposures are currently in use. The first is extended laminotomy/laminectomy from the upper lumbar level to the sacrum, which allows accurate identification of all L2–S2 roots/rootlets. The second is limited laminotomy exposing the conus/cauda equina at the thoracolumbar junction; this less invasive method limits accessibility to the roots. To optimize the accuracy and selectivity while minimizing invasiveness, the authors developed a tailored interlaminar procedure targeting the radicular levels involved in the harmful components of spasticity directly and individually.
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