Abstract

Background: Surgical correction of spinal deformities with coexisting intraspinal pathology (SDCIP) requires special consideration to minimize risks of further injury to an already abnormal spinal cord. However, there is a paucity of literature on this topic. Here, the authors present a pediatric patient with a residual pilocytic astrocytoma and syringomyelia who underwent surgical correction of progressive postlaminectomy kyphoscoliosis. Techniques employed are compared to those in the literature to compile a set of guidelines for surgical correction of SDCIP.

Methods: A systematic MEDLINE search was conducted using the following keywords; “pediatric,” “spinal tumor resection,” “deformity correction,” “postlaminectomy,” “scoliosis correction,” “intraspinal pathology,” “tethered cord,” “syringomyelia,” or “diastematomyelia.” Recommendations for surgical technique for pediatric SDCIP correction were reviewed.

Results: The presented case demonstrates recommendations that primarily compressive forces on the convexity of the coronal curve should be used when performing in situ correction of SDCIP. Undercorrection is favored to minimize risks of traction on the abnormal spinal cord. The literature yielded 13 articles describing various intraoperative techniques. Notably, seven articles described use of compressive forces on the convex side of the deformity as the primary mode of correction, while only five articles provided recommendations on how to safely and effectively surgically correct SDCIP.

Conclusion: The authors demonstrated with their case analysis and literature review that there are no clear current guidelines regarding the safe and effective techniques for in situ correction and fusion for the management of pediatric SDCIP.

Keywords: Intramedullary spinal tumor, Intraspinal pathology, Kyphoscoliosis, Pediatric spinal deformity correction

INTRODUCTION

Surgical techniques for the correction of idiopathic pediatric scoliotic deformities are well documented. However, various intraspinal pathologies, such as diastematomyelia, tethered cord, syringomyelia, and intramedullary spinal cord tumors (IMSCTs), create a unique set of considerations to be addressed during surgical planning and management of these three-dimensional spinal deformities. Unfortunately, there is little documentation of the appropriate surgical technique and guidelines for safely performing correction of spinal deformities with coexisting intraspinal pathology (SDCIP).

Here, the authors reviewed the literature on surgical techniques/recommendations for managing pediatric SDCIP, while also presenting an illustrative case of progressive postlaminectomy kyphoscoliosis in a pediatric patient 9 years after subtotal resection of an intramedullary spinal cord tumor (IMSCT).

MATERIALS AND METHODS

A pediatric case of SDCIP with IMSCT was reviewed and accompanied by a literature search of MEDLINE using of the keywords; “pediatric,” “intradural spinal tumor,” “spinal tumor resection,” “deformity correction,” “postlaminectomy,” “intraspinal pathology,” “tethered cord,” “syringomyelia,” or “diastematomyelia” [ Figure 1 ]. Exclusion and inclusion criteria for the review are described in Table 1 .

Figure 1:

(a) PRISMA flow diagram of citations identified and evaluated on literature review of scoliotic deformity correction in patients after spinal cord tumor resection. (b) PRISMA flow diagram of citations identified and evaluated on literature review of scoliotic deformity correction in patients with other intraspinal pathology.

Table 1:

Systematic review inclusion and exclusion criteria.

CASE REPORT

History

In 2007, at the age of 2, the patient underwent thoracic six (T6) to lumbar two (L2) laminectomies, for subtotal resection (STR) of a pilocytic astrocytoma with expansion duraplasty [ Figure 2 ] followed by adjuvant chemotherapy. Postoperatively, her only neurologic deficit was a neurogenic bladder, which required intermittent self-catheterization.

Figure 2:

T1 postcontrast thoracic (a) and lumbar (b) and T2 noncontrast thoracic (c) and lumbar (d) sagittal midline views of patient’s postoperative MRI demonstrate an expansile, intramedullary astrocytoma extending from T7 to L3 is demonstrated with associated syringohydromyelia extending from C2 to T7 with a remodeled and expanded spinal canal after decompressive laminectomies were performed from T7 to L3.

At 5 years of age, the patient had shoulder asymmetry in the horizontal plane and an increased thoracic kyphosis that was initially managed conservatively with external bracing. Over the next few years, the patient’s kyphoscoliosis continued to progress [ Figure 3 ], while interval MRIs demonstrated gross stability of her IMSCT [ Figure 4 ]. By 2016, despite stability of her intraspinal tumor pathology, serial standing scoliosis X-rays demonstrated interval progression of her deformity (i.e., with levoscoliosis of her T spine measuring 48.3° (previously 38.9° from T4-T11), dextroscoliosis of the L spine measuring 43° (previously 31.8° from T11-L5), and thoracic kyphosis (now 81°)). Having reached skeletal maturity [ Figure 3e ], the patient underwent surgical correction of her progressive kyphoscoliosis, in December 2016. Preoperative standing scoliosis and lateral bending X-rays were used to plan the extent of her fusion [ Figure 5 ], extending posteriorly from T3-L2.

Figure 3:

Serial standing scoliosis radiographs. (a,d) Preoperative AP and lateral radiographs before laminectomy and tumor resection. (b,e) First postoperative standing long-cassette thoracolumbar radiographs, AP and lateral, obtained in 2010, treated with external bracing. (c,f) Interval AP and lateral standing long-cassette thoracolumbar radiographs obtained in 2015 demonstrating a progressive kyphoscoliosis. (g) Continued progression of scoliosis seen on subsequent AP long-cassette thoracolumbar radiographs obtained in 2016. (h) Hand radiographs obtained to evaluate patient’s bone age in 2015, which was determined to be advanced of her chronologic age.

Figure 4:

Interval postoperative MRI obtained to evaluate for tumor recurrence or progression revealed new enhancing 6 mm nodule at level of T11/12, deemed clinically insignificant in context of progressive kyphoscoliosis and stable in appearance on subsequent MRIs. (a) T2 noncontrast image of thoracic spine in sagittal plane, with evidence of significant coronal deformity as well as T2 hyperintense cystic lesions in the lower thoracic spine. (b) T1 postcontrast image of the thoracic spine at the inferior aspect of T11 with evidence of enhancing nodule (blue arrow).

Figure 5:

Preoperative standing scoliosis radiographs including right lateral bending (a), upright AP (b), left lateral bending (c), and upright lateral (d) views. These films show a Lenke type 3+ scoliotic curve – levoscoliosis of the thoracic spine with cobb angle 46° and apex at T8, as well as a dextroscoliosis of the lumbar spine with a Cobb angle of 41° and apex at L2. There was minimal improvement of the patient’s coronal deformity on lateral bending. The patient also has a thoracic kyphosis of 80 degrees. The optimal lowest instrumented vertebra was determined by the neutralization of the L2-3 disc space on left-sided bending radiographs (c).

Operation

Laminectomies and facetectomies from T3-T12 ensured mobility of thoracic spine and extensive Smith-Petersen type osteotomies were undertaken from T5 to T11 to aid with correction of the kyphotic deformity. Pedicle screw fixation was performed and 5.5 mm CoCh rods, placed bilaterally from T3 to L2. Correction of the patient’s coronal and sagittal deformity was accomplished utilizing a combination of cantilever and in situ compression maneuvers. The patient’s coronal deformity was primarily fixed through compression of the convex aspect of her curve [ Figure 6 ]. Some degree of deformity was retained due to concerns that overcorrection may result in traction on the abnormally enlarged spinal cord. During this process, there was no noted change in the patient’s SSEPs or MEPs. A routine wake-up test was performed immediately following the deformity correction with the patient demonstrating satisfactory movement of both legs. An arthrodesis was performed using autograft mixed with morselized allograft. A plastic surgery team assisted with closure of the surgical wound. Following recovery from anesthesia, the patient was confirmed to have a stable neurologic exam with no new deficits.

Figure 6:

(a) Typical distraction and compressive forces (black arrows) placed along apex of coronal deformity in the absence of intraspinal pathology. (b) Utilization of primarily compressive forces (red arrows) along convexity of the curve to prevent over lengthening the spinal canal in the presence of intraspinal pathology, as was the case in our patient. Select axial T2-weighted noncontrast and one T1-weighted postcontrast MRI cross-sections of her spine highlight progressive intradural tumor (blue circles), cysts, and syringomyelia.

Postoperative course

The patient’s postoperative standing scoliosis radiographs demonstrated significant reduction of her kyphoscoliosis [ Figure 7 ]. Correction of the patient’s thoracic kyphotic deformity to within physiologic parameters was accomplished, as well as reduction of her thoracic levoscoliosis from 48° to 26°, her lumbar dextroscoliosis from 43° to 32°, and her kyphosis from 81° to 58°. Her postoperative course was uncomplicated and she was eventually discharged on postoperative day 4. On outpatient follow-up, the patient has recovered well from surgery and her pain has been well controlled with over 2 years of postoperative follow-up.

Figure 7:

Standing thoracolumbar radiographs immediately (a) and 2-year postoperative (b) demonstrating significant improvement in patient’s coronal deformity as well as restoration of a physiologic sagittal alignment.

LITERATURE REVIEW

Our review of the literature yielded four articles that described intraoperative approaches and techniques for the management of postlaminectomy spinal deformity in pediatric patients after IMSCT resection [ Table 2 ].[ 2 , 4 , 5 , 26 ] An additional nine articles were included, describing spinal deformity correction in patients with congenital scoliosis with intraspinal pathology, such as diastematomyelia, tethered cord, and syringomyelia with or without Chiari malformation [ Table 3 ].[ 1 , 3 , 8 , 11 , 19 - 21 , 23 , 27 ]

Surgical approaches described varied between single-stage posterior surgery versus staged deformity correction procedures with anterior release followed by posterior fusion. Nine articles described the use of osteotomies or posterior vertebral column resection to correct kyphoscoliotic deformities without lengthening the spinal column.[ 1 , 2 , 8 , 11 , 19 , 20 , 23 , 26 , 27 ] Of all the articles reviewed, seven described the use of compressive forces on the convex side of the deformity as the primary mode of correction.[ 5 , 12 , 27 ]

Table 2:

Systematic review of kyphoscoliosis correction in pediatric patients with intraspinal pathology – IMSCT.

Table 3:

Systematic review of kyphoscoliosis correction in pediatric patients with intraspinal pathology – DM, SM, and TC.

Neuromonitoring, with SSEPs or MEPs, was used in all but two articles reviewed.[ 3 , 23 ] Wake-up tests were used as the sole mode of neuromonitoring in one article,[ 1 ] due to unavailability of other modalities,[ 1 ] as a routine adjunct in four articles.[ 2 , 20 , 21 , 27 ] Changes in neuromonitoring signals were reported in three patients during intraoperative corrective maneuvers, but did not result in permanent neurologic sequelae.[ 2 , 21 ] Neurologic complications were reported in six patients (of 203 patients reported total; 2.9%) – three were transient not requiring further intervention,[ 1 , 19 , 26 ] while two had permanent new motor deficits,[ 3 , 8 ] and one whose deficits resolved only after reoperation and revision of instrumentation.[ 1 ]

DISCUSSION

The reported incidence of progressive spinal deformity after childhood resection of IMSCTs ranges from 16 to 80%, with increased incidence after laminectomies in the cervical or thoracic spine, and in younger patients.[ 6 , 24 , 25 ]Formatting... please wait Similarly, in cases of congenital scoliosis, early-onset scoliotic deformity may occur in 25–80% of patients with DM, TC, or SM, often with Chiari malformation.[ 16 , 22 ]

Given the authors’ experience, as illustrated in the presented case, and the prevalence of postlaminectomy spinal deformity requiring fusion, the authors sought to review the English literature and discuss surgical techniques currently used, to guide recommendations for safe maximal spinal deformity correction. The authors focused the review primarily on articles that discussed in situ deformity correction.[ 14 ] Overall, there is a paucity of literature describing best surgical technique for surgical fusion and deformity correction in the setting of IMSCT [ Table 2 ]. The majority of articles available in the English literature focus on incidence and risk factors for the development of postlaminectomy kyphoscoliosis in IMSCT patients. Addition of articles inclusive of other intraspinal pathologies, such as diastematomyelia, tethered cord, or syringomyelia with or without Chiari malformation, was still unable to provide substantial insight or guidelines on techniques of surgical correction of pediatric SDCIP [ Table 3 ]. These articles do not explore intraoperative approaches or corrective maneuvers in detail and focus their commentary predominantly on whether there is a need for neurosurgical intervention for varying spinal pathologies before deformity correction.

Having extensively reviewed the literature, the authors of this article would agree with recommendations favoring incomplete correction, rather than overcorrection, due to the increased risks of symptomatic spinal cord pathology. Expansile intraspinal pathology should be decompressed before deformity correction. Notably, a portion of articles in our literature review described rod rotation and translation primarily from the concave side[ 2 , 3 , 15 ] or primary use of distracting forces.[ 7 , 10 , 12 ] These techniques, which may be routinely employed in surgical correction of idiopathic scoliosis,[ 9 , 13 , 17 , 18 ] may not be as safe for surgical correction of SDCIP.[ 3 , 18 ] We believe that in the setting of abnormal expansile intraspinal pathology, such as residual low-grade glioma or syringomyelia as in the present case, applying distracting forces [ Figure 6 ] as the primary maneuver for correction of scoliotic spinal deformities may pose potential neurovascular risks.

The authors acknowledge that the literature review summary provided in Tables 2 - 3 is not streamlined, however, we believe that this speaks to the lack of literature addressing guidelines or recommendations for safe and effective surgical corrective techniques for this patient population. Few authors in the literature have made specific recommendations or proposed guidelines for the safe surgical correction of pediatric kyphoscoliosis in the setting of intraspinal pathology, primarily encouraging conservative and gradual deformity correction [ Table 4 ].[ 2 , 7 , 20 , 21 , 27 ] Although the surgical techniques employed by the authors in this case are not intrinsically novel, we believe that the provision of guidelines and points of consideration for surgical correction of spinal scoliotic deformities specific to patients with intraspinal pathology are a significant addition to the body of literature.

Table 4:

Recommendations/guidelines for surgical correction of kyphoscoliosis in pediatric patients with intraspinal pathology.

CONCLUSION

As illustrated in the present case, SDCIP can be safely and effectively surgically corrected using compressive maneuvers of the convexity of the curve with the goals of gradual and conservative correction to reduce the increased neurovascular risks secondary to an expanded and abnormal spinal cord.

Declaration of patient consent

Patient’s consent not required as patients identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Acknowledgments

All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Daphne Li, Douglas Anderson, and Russ Nockels. The first draft of the manuscript was written by Daphne Li and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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