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Lourdes C. Eco, Alison Brayton, William E. Whitehead and Andrew Jea

Chordomas are histologically benign tumors with local aggressive behavior. They arise from embryological remnants of the notochord at the clivus, mobile spine, and sacrum. Chordomas are rare tumors in the pediatric age group. Their surgical management is difficult, given their propensity for inaccessible anatomical regions, and proximity to critical neurovascular structures. While en bloc resection with surgical margins has been advocated as the preferred approach for chordomas, tumor characteristics and violation of adjacent anatomical boundaries may not allow for safe en bloc resection of the tumor. Here, the authors present the case of a C1 chordoma in a 5-year-old boy with epidural and prevertebral extension. The patient’s treatment consisted of a far-lateral approach for resection of the tumor and C1 arch, followed by circumferential reconstruction of the craniocervical junction with an expandable cage spanning the skull base to C2, and posterior occipitocervical spinal instrumentation. At 42 months after surgery, the patient remains neurologically intact with stable oncological status, and no evidence of craniocervical junction instrumentation failure.

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Arvind C. Mohan, Howard L. Weiner, Carrie A. Mohila, Adekunle Adesina, Murali Chintagumpala, Daniel Curry, Andrew Jea, Jonathan J. Lee, Sandi K. Lam, William E. Whitehead, Robert Dauser, Daniel Yoshor and Guillermo Aldave

OBJECTIVE

The indication for and timing of surgery for epilepsy associated with low-grade mixed neuronal-glial tumors may be controversial. The purpose of this study was to evaluate the effect of resection and associated variables on epilepsy and on progression-free survival (PFS).

METHODS

A retrospective chart review of patients treated between 1992 and 2016 was conducted to identify individuals with epilepsy and low-grade gliomas or neuronal-glial tumors who underwent resective surgery. Data analyzed included age at epilepsy onset, age at surgery, extent of resection, use of electrocorticography, the number of antiepileptic drugs (AEDs) before and after surgery, the presence of dysplasia, Engel class, histological findings, and PFS. The institutional review board protocol was specifically approved to conduct this study.

RESULTS

A total of 107 patients were identified. The median follow-up was 4.9 years. The most common pathology was dysembryoplastic neuroepithelial tumor (36.4%), followed by ganglioglioma (31.8%). Eighty-four percent of patients had Engel class I outcomes following surgery. Gross-total resection was associated with a higher likelihood of an Engel class I outcome (90%) as compared to subtotal resection (58%) (p = 0.0005). Surgery reduced the AED burden, with 40% of patients requiring no AEDs after surgery (p < 0.0001). Children with neurodevelopmental comorbidities (n = 5) uniformly did not experience seizure improvement following resection (0% vs 83% overall; p < 0.0001). Electrocorticography was used in 33% of cases and did not significantly increase class I outcomes. PFS was 90% at 5 years. Eleven percent of tumors recurred, with subtotal resection more likely to result in recurrence (hazard ratio 5.3, p = 0.02). Histological subtype showed no significant impact on recurrence.

CONCLUSIONS

Gross-total resection was strongly associated with Engel class I outcome and longer PFS. Further studies are needed to elucidate the suitable time for surgery and to identify factors associated with oncological transformation.

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Spinal instrumentation in infants, children, and adolescents: a review

JNSPG 75th Anniversary Invited Review Article

Stephen Mendenhall, Dillon Mobasser, Katherine Relyea and Andrew Jea

OBJECTIVE

The evolution of pediatric spinal instrumentation has progressed in the last 70 years since the popularization of the Harrington rod showing the feasibility of placing spinal instrumentation into the pediatric spine. Although lacking in pediatric-specific spinal instrumentation, when possible, adult instrumentation techniques and tools have been adapted for the pediatric spine. A new generation of pediatric neurosurgeons with interest in complex spine disorder has pushed the field forward, while keeping the special nuances of the growing immature spine in mind. The authors sought to review their own experience with various types of spinal instrumentation in the pediatric spine and document the state of the art for pediatric spine surgery.

METHODS

The authors retrospectively reviewed patients in their practice who underwent complex spine surgery. Patient demographics, operative data, and perioperative complications were recorded. At the same time, the authors surveyed the literature for spinal instrumentation techniques that have been utilized in the pediatric spine. The authors chronicle the past and present of pediatric spinal instrumentation, and speculate about its future.

RESULTS

The medical records of the first 361 patients who underwent 384 procedures involving spinal instrumentation from July 1, 2007, to May 31, 2018, were analyzed. The mean age at surgery was 12 years and 6 months (range 3 months to 21 years and 4 months). The types of spinal instrumentation utilized included occipital screws (94 cases); C1 lateral mass screws (115 cases); C2 pars/translaminar screws (143 cases); subaxial cervical lateral mass screws (95 cases); thoracic and lumbar spine traditional-trajectory and cortical-trajectory pedicle screws (234 cases); thoracic and lumbar sublaminar, subtransverse, and subcostal polyester bands (65 cases); S1 pedicle screws (103 cases); and S2 alar-iliac/iliac screws (56 cases). Complications related to spinal instrumentation included hardware-related skin breakdown (1.8%), infection (1.8%), proximal junctional kyphosis (1.0%), pseudarthroses (1.0%), screw malpositioning (0.5%), CSF leak (0.5%), hardware failure (0.5%), graft migration (0.3%), nerve root injury (0.3%), and vertebral artery injury (0.3%).

CONCLUSIONS

Pediatric neurosurgeons with an interest in complex spine disorders in children should develop a comprehensive armamentarium of safe techniques for placing rigid and nonrigid spinal instrumentation even in the smallest of children, with low complication rates. The authors’ review provides some benchmarks and outcomes for comparison, and furnishes a historical perspective of the past and future of pediatric spine surgery.

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Kyung Shin Kang, Jeff Lastfogel, Laurie L. Ackerman, Andrew Jea, Alexander G. Robling and Sunil S. Tholpady

OBJECTIVE

Cranial defects can result from trauma, infection, congenital malformations, and iatrogenic causes and represent a surgical challenge. The current standard of care is cranioplasty, with either autologous or allogeneic material. In either case, the intrinsic vascularity of the surrounding tissues allows for bone healing. The objective of this study was to determine if mechanotransductive gene manipulation would yield non–weight-bearing bone regeneration in a critical size calvarial defect in mice.

METHODS

A mouse model of Sost deletion in Sost knockout (KO) mice was created in which the osteocytes do not express sclerostin. A critical size calvarial defect (4 mm in diameter) was surgically created in the parietal bone in 8-week-old wild-type (n = 8) and Sost KO (n = 8) male mice. The defects were left undisturbed (no implant or scaffold) to simulate a traumatic calvariectomy model. Eight weeks later, the animals were examined at necropsy by planimetry, histological analysis of new bone growth, and micro-CT scanning of bone thickness.

RESULTS

Defects created in wild-type mice did not fill with bone over the study period of 2 months. Genetic downregulation of sclerostin yielded animals that were able to regenerate 40% of the initial critical size defect area 8 weeks after surgery. A thin layer of bone covered a significant portion of the original defect in all Sost KO animals. A statistically significant increase in bone volume (p < 0.05) was measured in Sost KO mice using radiodensitometric analysis. Immunohistochemical analysis also confirmed that this bone regeneration occurred through the Wnt pathway and originated from the edge of the defect; BMP signaling did not appear to be affected by sclerostin.

CONCLUSIONS

Mechanical loading is an important mechanism of bone formation in the cranial skeleton and is poorly understood. This is partially due to the fact that it is difficult to load bone in the craniomaxillofacial skeleton. This study suggests that modulation of the Wnt pathway, as is able to be done with monoclonal antibodies, is a potentially efficacious method for bone regeneration that requires further study.

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Nikita G. Alexiades, Edward S. Ahn, Jeffrey P. Blount, Douglas L. Brockmeyer, Samuel R. Browd, Gerald A. Grant, Gregory G. Heuer, Todd C. Hankinson, Bermans J. Iskandar, Andrew Jea, Mark D. Krieger, Jeffrey R. Leonard, David D. Limbrick Jr., Cormac O. Maher, Mark R. Proctor, David I. Sandberg, John C. Wellons III, Belinda Shao, Neil A. Feldstein and Richard C. E. Anderson

OBJECTIVE

Complications after complex tethered spinal cord (cTSC) surgery include infections and cerebrospinal fluid (CSF) leaks. With little empirical evidence to guide management, there is variability in the interventions undertaken to limit complications. Expert-based best practices may improve the care of patients undergoing cTSC surgery. Here, authors conducted a study to identify consensus-driven best practices.

METHODS

The Delphi method was employed to identify consensual best practices. A literature review regarding cTSC surgery together with a survey of current practices was distributed to 17 board-certified pediatric neurosurgeons. Thirty statements were then formulated and distributed to the group. Results of the second survey were discussed during an in-person meeting leading to further consensus, which was defined as ≥ 80% agreement on a 4-point Likert scale (strongly agree, agree, disagree, strongly disagree).

RESULTS

Seventeen consensus-driven best practices were identified, with all participants willing to incorporate them into their practice. There were four preoperative interventions: (1, 2) asymptomatic AND symptomatic patients should be referred to urology preoperatively, (3, 4) routine preoperative urine cultures are not necessary for asymptomatic AND symptomatic patients. There were nine intraoperative interventions: (5) patients should receive perioperative cefazolin or an equivalent alternative in the event of allergy, (6) chlorhexidine-based skin preparation is the preferred regimen, (7) saline irrigation should be used intermittently throughout the case, (8) antibiotic-containing irrigation should be used following dural closure, (9) a nonlocking running suture technique should be used for dural closure, (10) dural graft overlay should be used when unable to obtain primary dural closure, (11) an expansile dural graft should be incorporated in cases of lipomyelomeningocele in which primary dural closure does not permit free flow of CSF, (12) paraxial muscles should be closed as a layer separate from the fascia, (13) routine placement of postoperative drains is not necessary. There were three postoperative interventions: (14) postoperative antibiotics are an option and, if given, should be discontinued within 24 hours; (15) patients should remain flat for at least 24 hours postoperatively; (16) routine use of abdominal binders or other compressive devices postoperatively is not necessary. One intervention was prioritized for additional study: (17) further study of additional gram-negative perioperative coverage is needed.

CONCLUSIONS

A modified Delphi technique was used to develop consensus-driven best practices for decreasing wound complications after cTSC surgery. Further study is required to determine if implementation of these practices will lead to reduced complications. Discussion through the course of this study resulted in the initiation of a multicenter study of gram-negative surgical site infections in cTSC surgery.

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Stephen K. Mendenhall, Andrew Huh, Janit Pandya, Vincent Alentado, Karl Balsara, Chang Ho and Andrew Jea

OBJECTIVE

The revelation of normative radiographic measurements for the developing pediatric spine is incomplete. The purpose of this analysis was to determine the normal range of asymmetry of the lateral atlantodental interval (LADI) and define age- and sex-related differences.

METHODS

A total of 3072 children aged 0–18 years who underwent CT scanning of the cervical spine were identified at Riley Hospital for Children between 2005 and 2017. Patients were stratified by sex and age (in years) into 36 cohorts. Following this stratification, patients within each group were randomly selected for inclusion until 15 patients in each group had been measured (quota sampling). A total of 540 patients were included for study. Right and left linear measurements were performed in the CT axial plane at the C-1 midlateral mass level.

RESULTS

The overall mean difference between the right and left LADI was 0.09 ± 1.23 mm (range -6.05 to 4.87 mm). The magnitude of this asymmetry remained statistically insignificant across age groups (p = 0.278) and sex (p = 0.889). The intraclass correlation coefficient was 0.805 (95% CI 0.779–0.829).

CONCLUSIONS

Asymmetry of the LADI is not unusual in asymptomatic children. There is no appreciable difference in magnitude of this asymmetry across age ranges and sex. Measurement of LADI asymmetry shows “good” reliability and is easy to perform. Pediatric neurosurgeons, emergency department physicians, and radiologists should be aware of normative values of asymmetry when interpreting CT scans of the cervical spine. This may prevent unnecessary further workup with dynamic CT or MRI.

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Laurie L. Ackerman, Daniel H. Fulkerson, Andrew Jea and Jodi L. Smith

OBJECTIVE

Patients with shunts often interact with providers distant from their primary hospital, making it important that the parent(s)/guardian(s) is well versed in the type of shunt implanted and symptoms of malfunction/infection. This is particularly important with magnetic-sensitive programmable valves, as the use of MRI becomes more prevalent.

METHODS

Over a 6-month period, primary caregivers of 148 consecutive patients who received shunts were prospectively administered questionnaires at clinic visits. Caregivers were asked to do the following: 1) identify shunt valve name, type, and setting if applicable; 2) list symptoms of shunt malfunction/infection; and 3) indicate whether they had access to references regarding shunt type/setting, booklets from the Hydrocephalus Association, and quick reference cards with symptoms of shunt malfunction/infection. One cohort of caregivers (n = 75) was asked to carry informational cards with shunt valve/setting information (group I); this cohort was compared with another subgroup of caregivers (n = 73) not carrying cards (group II).

RESULTS

The mean (± SD) age of patients at implantation/revision was 3.71 ± 4.91 years, and the age at follow-up was 6.12 ± 5.4 years. The average time from surgery to administration of the questionnaire was 2.38 ± 3.22 years. There were 86 new shunt insertions and 62 revisions. One hundred twenty-eight caregivers (87%) could identify the type of valve (programmable vs nonprogrammable). On the other hand, only 72 caregivers (49%) could identify the valve name. Fifty-four of 73 (74%) caregivers of patients who had shunts with programmable valves could correctly identify the valve setting. One hundred caregivers (68%) had a copy of the Hydrocephalus Association booklet, and 103 (70%) had quick reference cards. Eighty caregivers (54%) had references on shunt type/setting. Most caregivers (127 [86%]) could name ≥ 3 signs/symptoms of shunt malfunction, with vomiting (61%), headache (49%), and sleeps more/lethargic (35%) most frequently reported. Caregivers of patients in group I were more likely to have cards with symptoms of shunt infection or malfunction (p = 0.015); have information cards regarding shunt type/setting (p < 0.001); and correctly identify valve type (p = 0.001), name (p < 0.001), and setting if programmable (p = 0.0016). There were no differences in ability to list symptoms of shunt malfunction or infection (p = 0.8812) or in access to Hydrocephalus Association booklets (p = 0.1288). There were no significant demographic differences between the groups, except that group I patients had a shorter time from surgery to last follow-up (1.66 vs 3.17 years; p = 0.0001).

CONCLUSIONS

Education regarding the care of patients with shunts by providing written cards with shunt type/setting and access to reference materials seems to be effective. Developing plans for guided instruction with assessment in the clinic setting of a caregiver’s knowledge is important for patient safety.

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Zaid Aljuboori, Jacob Archer, Wei Huff, Amee Moreno and Andrew Jea

Intrathecal baclofen has been suggested as an effective and safe treatment for intractable spasticity and dystonia. Techniques of lumbar and intraventricular catheter placement have been previously described. The purpose of this study was to describe a technique to implant catheters for intrathecal baclofen infusion through C1–2 puncture.

Four of 5 consecutively treated patients underwent successful placement of catheters for intrathecal baclofen. There were no instances of infection, CSF leak, or catheter migration seen during a follow-up period of at least 6 months; furthermore, there were no occurrences of vertebral artery or spinal cord injury. All patients had an effective stabilization or reduction of their upper-extremity, lower-extremity, or trunk tone. There were no cases of worsening hypertonia.

The authors’ preliminary experience with C1–2 puncture for placement of the intrathecal baclofen catheter seems to indicate that this is a safe and efficacious technique. Lessons learned from the failed attempt at C1–2 puncture will be delineated.

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Jonathan N. Sellin, Jeffrey S. Raskin, Kristen A. Staggers, Alison Brayton, Valentina Briceño, Amee J. Moreno and Andrew Jea

Thoracic and lumbar cortical bone trajectory pedicle screws have been described in adult spine surgery. They have likewise been described in pediatric CT-based morphometric studies; however, clinical experience in the pediatric age group is limited. The authors here describe the use of cortical bone trajectory pedicle screws in posterior instrumented spinal fusions from the upper thoracic to the lumbar spine in 12 children. This dedicated study represents the initial use of cortical screws in pediatric spine surgery.

The authors retrospectively reviewed the demographics and procedural data of patients who had undergone posterior instrumented fusion using thoracic, lumbar, and sacral cortical screws in children for the following indications: spondylolysis and/or spondylolisthesis (5 patients), unstable thoracolumbar spine trauma (3 patients), scoliosis (2 patients), and tumor (2 patients).

Twelve pediatric patients, ranging in age from 11 to 18 years (mean 15.4 years), underwent posterior instrumented fusion. Seventy-six cortical bone trajectory pedicle screws were placed. There were 33 thoracic screws and 43 lumbar screws. Patients underwent surgery between April 29, 2015, and February 1, 2016. Seven (70%) of 10 patients with available imaging achieved a solid fusion, as assessed by CT. Mean follow-up time was 16.8 months (range 13–22 months). There were no intraoperative complications directly related to the cortical bone trajectory screws. One patient required hardware revision for caudal instrumentation failure and screw-head fracture at 3 months after surgery.

Mean surgical time was 277 minutes (range 120–542 minutes). Nine of the 12 patients received either a 12- or 24-mg dose of recombinant human bone morphogenic protein 2. Average estimated blood loss was 283 ml (range 25–1100 ml).

In our preliminary experience, the cortical bone trajectory pedicle screw technique seems to be a reasonable alternative to the traditional trajectory pedicle screw placement in children. Cortical screws seem to offer satisfactory clinical and radiographic outcomes, with a low complication profile.