Reflex variability in selective dorsal rhizotomy

Weiss, Ira P.

doi:10.3171/jns.1993.79.3.0346

Cited by 34 publications

(25 citation statements)

References 21 publications

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“…Spatial facilitation, in which a nerve root demonstrates an abnormal response, while no individual rootlet can be identified as contributing to that response, has been documented [23, 24]. Furthermore, experimental studies have shown that intraoperative electromyographic responses of individual rootlets are inconsistent and not reproducible, further suggesting that current techniques are not reliable for rootlet selection [25].…”

Section: Discussionmentioning

confidence: 99%

“…Although it is commonly accepted practice to establish a threshold for reflex activation prior to recording a response, potential errors have been described at this initial stage in the procedure [23, 24]. Furthermore, the designation of responses as ‘normal’ and ‘abnormal’ has been challenged.…”

Section: Discussionmentioning

confidence: 99%

“…Studies have documented a paucity of normal responses in spastic patients [8, 26, 27], as well as abnormal responses in patients with no clinical evidence of spasticity [8, 27]. Potential error has also been attributed to technical difficulties [24, 26]. …”

Section: Discussionmentioning

confidence: 99%

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Nonselective Partial Dorsal Rhizotomy: A Clinical Experience with 1-Year Follow-Up

2000

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The ability to perform a ‘selective’ dorsal rhizotomy has been challenged. EMG responses are inconsistent and often do not represent reflex responses. We perform nonselective partial dorsal rhizotomy (NSPDR) when reflex response is not evident. Ten children undergoing primarily NSPDR were evaluated preoperatively and postoperatively with the Modified Ashworth Scale, gait lab analyses gross motor function measure and the NSPDR was performed by nonselectively sectioning 50–75% of the dorsal roots not demonstrating a reflex response. Standard selective rhizotomy was performed in the remainder. Only 17 of 106 (16%) dorsal roots demonstrated reflex responses. The results reported in this study demonstrate a benefit to patients undergoing primarily NSPDR which is similar to that reported for patients in whom a selective procedure was intended.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Nonselective Partial Dorsal Rhizotomy: A Clinical Experience with 1-Year Follow-Up

2000

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“…The utilization of EMG guidance in SDR has been called into question in a number of instances despite good clinical results [18,19]. The originally proposed criteria [20], including spreading, sustained response, and threshold responses to single stimuli, have been shown to be present in nonspastic children, which suggests they are not necessarily indicative of a spastic process [11].…”

Section: Discussionmentioning

confidence: 99%

Infra-Conus Single-Level Laminectomy for Selective Dorsal Rhizotomy: Technical Advance

et al. 2016

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Background/Aims: Selective dorsal rhizotomy for spastic cerebral palsy is an effective and well-validated surgical approach. Multiple techniques have been described in the past including multiple laminectomies and a single-level laminectomy at the level of the conus. There is considerable technical challenge involved with a single-level laminectomy approach. Methods: We report here a modification of the single-level laminectomy that selectively analyzes each individual nerve root with electromyography to separate dorsal and ventral nerve roots through comparison of stimulus responses. Results: In 18 children with cerebral palsy who underwent this operation there was a mean improvement in the Modified Ashworth Scale of 2.0 with no reported incidence of muscle weakness, sensory loss, or neurogenic bladder. Conclusion: This approach allows for a modification of selective dorsal rhizotomy through a single-level laminectomy and tailors the selection of nerve root sectioning to the individual patient of interest while still maintaining its effectiveness.

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“…An 'abnor mal' response has been recorded in children without clini cal spasticity [4,7], questioning the assumptions of an abnormal reflex response. Weiss and Schiff [6] found con siderable variability of the electromyographic responses in several whole dorsal roots, and attributed this to intrin sic spinal cord reflex variability as well as technical fac tors. Moreover, Logigian et al [8] have demonstrated that currently used techniques yield responses that commonly result from nonreflex ventral root costimulation.…”

Section: Introductionmentioning

confidence: 99%

The Electromyographic Responses to Dorsal Rootlet Stimulation during Partial Dorsal Rhizotomy Are Inconsistent

Warf¹,

Nelson

1996

Pediatr Neurosurg

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Concerns have arisen regarding the ability of physiologic techniques to select rootlets mediating spasticity in children undergoing partial dorsal rhizotomy (PDR) for the treatment of spastic gait from cerebral palsy. To determine whether these physiologic responses are reproducible, 60 rootlets in 6 patients were graded from 0 to 4+ according to the system first reported by Phillips and Park, and then retested and graded using a randomized, blinded paradigm. Two thirds of the rootlets had one or more grade difference between the two trials, and 25% had a grade change of 3 or more. Only 4 of 23 rootlets with a ‘normal’ response (grade 0) on one test were also graded normal on the other test. Only 2 of 14 rootlets with a bilateral response (grade 4+) had a bilateral response on both trials. Statistical analysis demonstrated no correlation and poor agreement between trials. Regardless of whether responses are reflex in origin with technical or physiologic variability, or the consequence of stimulus spread to ventral roots, we found inconsistent responses with commonly used methods and the criteria most agreed upon. These findings suggest that currently used techniques are not reliable for rootlet ‘selection’ and result only in a random partial rhizotomy.

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Reflex variability in selective dorsal rhizotomy

Cited by 34 publications

References 21 publications

Nonselective Partial Dorsal Rhizotomy: A Clinical Experience with 1-Year Follow-Up

Nonselective Partial Dorsal Rhizotomy: A Clinical Experience with 1-Year Follow-Up

Infra-Conus Single-Level Laminectomy for Selective Dorsal Rhizotomy: Technical Advance

The Electromyographic Responses to Dorsal Rootlet Stimulation during Partial Dorsal Rhizotomy Are Inconsistent

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