Transabdominal motor evoked potential neuromonitoring of lumbosacral spine surgery.

BACKGROUND CONTEXT: Transcranial Motor Evoked Potentials (TcMEPs) can improve intraoperative detection of femoral plexus and nerve root injury during lumbosacral spine surgery. However, even under ideal conditions, TcMEPs are not completely free of false-positive alerts due to the immobilizing effect of general anesthetics, especially in the proximal musculature. The application of transcutaneous stimulation to activate ventral nerve roots directly at the level of the conus medularis (bypassing the brain and spinal cord) has emerged as a method to potentially monitor the motor component of the femoral plexus and lumbosacral nerves free from the blunting effects of general anesthesia. PURPOSE: To evaluate the reliability and efficacy of transabdominal motor evoked potentials (TaMEPs) compared to TcMEPs during lumbosacral spine procedures. DESIGN: We present the findings of a single-center 12-month retrospective experience of all lumbosacral spine surgeries utilizing multimodality intraoperative neuromonitoring (IONM) consisting of TcMEPs, TaMEPs, somatosensory evoked potentials (SSEPs), electromyography (EMG), and electroencephalography. PATIENT SAMPLE: Two hundred and twenty patients having one, or a combination of lumbosacral spine procedures, including anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), posterior spinal fusion (PSF), and/or transforaminal lumbar interbody fusion (TLIF). OUTCOME MEASURES: Intraoperative neuromonitoring data was correlated to immediate post-operative neurologic examinations and chart review. METHODS: Baseline reliability, false positive rate, true positive rate, false negative rate, area under the curve at baseline and at alerts, and detection of pre-operative deficits of TcMEPs and TaMEPs were compared and analyzed for statistical significance. The relationship between transcutaneous stimulation voltage level and patient BMI was also examined. RESULTS: TaMEPs were significantly more reliable than TcMEPs in all muscles except abductor hallucis. Of the 27 false positive alerts, 24 were TcMEPs alone, and 3 were TaMEPs alone. Of the 19 true positives, none were detected by TcMEPs alone, 3 were detected by TaMEPs alone (TcMEPs were not present), and the remaining 16 true positives involved TaMEPs and TcMEPs. TaMEPs had a significantly larger area under the curve (AUC) at baseline than TcMEPs in all muscles except abductor hallucis. The percent decrease in TcMEP and TaMEP AUC during LLIF alerts was not significantly different. Both TcMEPs and TaMEPs reflected three pre-existing motor deficits. Patient BMI and TaMEP stimulation intensity were found to be moderately positively correlated. CONCLUSIONS: These findings demonstrate the high reliability and predictability of TaMEPs and the potential added value when TaMEPs are incorporated into multimodality IONM during lumbosacral spine surgery.

The Role of Fibrinogen-Like Protein 2 on Immunosuppression and Malignant Progression in Glioma.

BACKGROUND: Virtually all low-grade gliomas (LGGs) will progress to high-grade gliomas (HGGs), including glioblastoma, the most common malignant primary brain tumor in adults. A key regulator of immunosuppression, fibrinogen-like protein 2 (FGL2), may play an important role in the malignant transformation of LGG to HGG. We sought to determine the mechanism of FGL2 on tumor progression and to show that inhibiting FGL2 expression had a therapeutic effect. METHODS: We analyzed human gliomas that had progressed from low- to high-grade for FGL2 expression. We modeled FGL2 overexpression in an immunocompetent genetically engineered mouse model to determine its effect on tumor progression. Tumors and their associated microenvironments were analyzed for their immune cell infiltration. Mice were treated with an FGL2 antibody to determine a therapeutic effect. Statistical tests were two-sided. RESULTS: We identified increased expression of FGL2 in surgically resected tumors that progressed from low to high grade (n = 10). The Cancer Genome Atlas data showed that LGG cases with overexpression of FGL2 (n = 195) had statistically significantly shorter survival (median = 62.9 months) compared with cases with low expression (n = 325, median = 94.4 months, P < .001). In a murine glioma model, HGGs induced with FGL2 exhibited a mesenchymal phenotype and increased CD4+ forkhead box P3 (FoxP3)+ Treg cells, implicating immunosuppression as a mechanism for tumor progression. Macrophages in these tumors were skewed toward the immunosuppressive M2 phenotype. Depletion of Treg cells with anti-FGL2 statistically significantly prolonged survival in mice compared with controls (n = 11 per group, median survival = 90 days vs 62 days, P = .004), shifted the phenotype from mesenchymal HGG to proneural LGG, and decreased M2 macrophage skewing. CONCLUSIONS: FGL2 facilitates glioma progression from low to high grade. Suppressing FGL2 expression holds therapeutic promise for halting malignant transformation in glioma.

Analysis of the inhibitors of apoptosis identifies BIRC3 as a facilitator of malignant progression in glioma.

Gliomas, the most common primary brain tumor in humans, include a spectrum of disease. High-grade gliomas (HGG), such as glioblastoma, may arise from low-grade gliomas (LGG) that have a more indolent course. The process of malignant transformation (MT) of LGG to HGG is poorly understood but likely involves the activation of signaling programs that suppress apoptosis. We previously showed that Survivin (BIRC5) plays a role in malignant progression of glioma. Here, we investigated the role of the remaining members of the Inhibitors of Apoptosis (IAP) family on promoting MT in glioma. Utilizing expression data from the cancer genome atlas (TCGA), we identified BIRC3 as a key facilitator of MT from LGG to HGG. TCGA HGGs with high expression of BIRC 3 demonstrated a survival disadvantage and expression levels of BIRC3 were also significantly higher in TCGA HGG compared to TCGA LGG cases. We validated our findings from TCGA by using matched human specimens to show that BIRC expression is increased in HGG compared to their precursor LGG lesions. Using a unique murine model of glioma, we show that overexpression of BIRC3 promotes higher grade glioma and significantly reduces tumor-free survival in mice.

An Intraoperative Look at Failure of Flow Diversion: When Additional or Alternative Treatments Should Be Considered.

BACKGROUND: The pipeline embolization device (PED) is a flow-diverting stent that provides an additional treatment modality in the management of intracranial aneurysms. An aneurysm treated with a flow diverter is expected to involute over time, contrary to the immediate obliteration expected by surgical clipping or coiling. Yet, which aneurysms will respond to PED therapy and the time frame to expect full obliteration remain unclear. CASE DESCRIPTION: We report the unusual case of a 50-year-old woman with multiple (4 total) intracranial aneurysms who underwent multimodality treatment. Two aneurysms were treated with PEDs. Nine months later, the patient underwent a craniotomy for treatment of an additional aneurysm; at the time of surgery, one of the PED-treated aneurysms was noted to be clearly obliterated, and the other was visualized to be filling. The ophthalmic artery arose from the persistently filling aneurysm. The aneurysm was treated by clip ligation without incident. CONCLUSIONS: The rate of PED aneurysm obliteration increases with longer follow-up; however, the time frame for observing a persistently filling aneurysm before additional treatment is considered remains unknown. Some aneurysms may never close even after discontinuation of dual antiplatelet therapy. Ophthalmic artery aneurysms have been noted to fail treatment with PED based on the anatomic relationship of the aneurysm to the ophthalmic artery. This case provokes us to consider factors that may affect the latency to aneurysm obliteration, including aneurysm size, aneurysm morphology, patient gender, failure of previous aneurysm treatment, and duration of time from initial endovascular treatment.

Prognostic Factors Influencing the Outcome of 64 Consecutive Patients Undergoing Surgery for Metastatic Melanoma of the Spine.

BACKGROUND: Melanoma metastases to the spine remain a challenge for neurosurgeons. OBJECTIVE: To identify factors associated with survival in a series of patients who underwent spinal surgery for metastatic melanoma. METHODS: We retrospectively reviewed all patients (n = 64) who received surgical intervention for melanoma metastases to the spine at the University of Texas MD Anderson Cancer Center between July 1993 and March 2012. RESULTS: No patients were excluded from the study, and vital status data were available for all patients. Median overall survival was 5.7 months (95% confidence interval, 2.7-28.7). On univariate survival analysis, diagnosis of spinal metastasis after prior diagnosis of systemic metastasis, higher total spinal disease burden (including but not exclusive to the operative site), presence of progressive systemic disease at the moment of spine surgery, and postoperative complications were associated with poorer overall survival, whereas the presence of only bone metastasis at the moment of surgery was associated with improved overall survival. On multivariate survival analysis, both progressive systemic disease at the moment of spine surgery and total spinal disease burden of ≥3 vertebral levels were significantly associated with worse overall survival (hazard ratio, 6.00; 95% confidence interval, 3.19-11.28; P < .001; and hazard ratio, 2.87; 95% confidence interval, 1.62-5.07; P < .001, respectively). CONCLUSION: On multivariate analysis, involvement of ≥3 vertebral bodies and progressive systemic disease were associated with worse overall survival. Consideration of these factors should influence surgical decision making in this patient population.

Surgical treatment of congenital thoracolumbar spondyloptosis in a 2-year-old child with vertebral column resection and posterior-only circumferential reconstruction of the spine column: case report.

Spondyloptosis refers to complete dislocation of a vertebral body onto another. The L5-S1 level is frequently affected. As this condition is rare, few published reports describing its clinical features and surgical outcomes exist, especially in the pediatric patient population. The authors report the presentation, pathological findings, and radiographic studies of a 2-year-old girl who presented to Texas Children's Hospital with a history since birth of progressive spastic paraparesis. Preoperative CT and MRI showed severe spinal cord compression associated with T11-12 spondyloptosis. The patient underwent a single-stage posterior approach for complete resection of the dysplastic vertebral bodies at the apex of the spinal deformity with reconstruction and stabilization of the vertebral column using a titanium expandable cage and pedicle screws. At the 12-month follow-up, the patient remained neurologically stable without any radiographic evidence of instrumentation failure or loss of alignment. To the best of the authors' knowledge, there have been only 2 other children with congenital thoracolumbar spondyloptosis treated with the above-described strategy. The authors describe their case and review the literature to discuss the aggregate clinical features, surgical strategies, and operative outcomes for congenital thoracolumbar spondyloptosis.

Signal transducer and activator of transcription 5b drives malignant progression in a PDGFB-dependent proneural glioma model by suppressing apoptosis.

Signal transducer and activator of transcription 5b (STAT5b) is likely the relevant STAT5 isoform with respect to the process of malignant progression in gliomas. STAT5b is a latent cytoplasmic protein involved in cell signaling through the modulation of growth factors, apoptosis, and angiogenesis. Previous in vitro studies have shown increased STAT5b expression in glioblastomas relative to low-grade tumors and normal brain. We recently demonstrated that phosphorylated STAT5b associates with delta epidermal growth factor receptor in the nucleus and subsequently binds the promoters of downstream effector molecules, including aurora kinase A. Analysis of TCGA dataset reveals that STAT5b is predominantly expressed in proneural (PN) gliomas relative to mesenchymal and neural gliomas. Here, we modeled ectopic expression of STAT5b in vivo using a platelet-derived growth factor subunit B (PDGFB)-dependent mouse model of PN glioma to determine its effect on tumor formation and progression. We showed that coexpression of STAT5b and PDGFB in mice yielded a significantly higher rate of high-grade gliomas than PDGFB expression alone. We also observed shorter survival in the combined expression set. High-grade tumors from the STAT5b + PDGFB expression set were found to have a lower rate of apoptosis than those from PDGFB alone. Furthermore, we showed that increased expression of STAT5b + PDGFB led to increased expression of downstream STAT5b targets, including Bcl-xL, cyclin D1 and aurora kinase A in high-grade tumors when compared to tumors derived from PDGFB alone. Our findings show that STAT5b promotes the malignant transformation of gliomas, particularly the PN subtype, and is a potential therapeutic target.

Far lateral paracondylar versus transcondylar approach in the pediatric age group: CT morphometric analysis.

This study aimed to determine if partial removal of the occipital condyle provides a significant increase in visibility and "angle of attack" for treating lesions with extension ventral to the brainstem in children using CT morphometric data. Morphometric analysis was performed in 199 children using CT scans. Angle of attack was measured for both the paracondylar and transcondylar far lateral approach. Statistical analysis was performed using paired or unpaired Student's t-tests (p<0.05) and linear regression analysis. For the far lateral paracondylar approach, the overall angle of attack was 85 ± 9 degrees (range, 60-119 degrees). The overall angle of attack for the far lateral transcondylar approach was 70 ± 9 degrees (range, 48-105 degrees). This difference was significant (p<0.0001). Based on our data, resection of one-third of the occipital condyle in a far lateral transcondylar approach can improve angle of attack by approximately 15 degrees, regardless of age or sex, in the pediatric age group. It is important to keep in mind that there are risks attendant to resection of the occipital condyle, thus the resection of the occipital condyle in children should not be a mandatory part of the far lateral approach; rather, the decision-making should be individualized and considered on a case-by-case basis.

Predictors of outcome in civilians with gunshot wounds to the head upon presentation.

OBJECT: Prediction of outcome from initial presentation after a gunshot wound to the head (GSWH) is essential to further clinical decision making. The authors' goals are to report the survival and functional outcomes of these patients, to identify prognostic factors, and to propose a scoring system that can predict their outcome. METHODS: The records of 199 patients admitted with a GSWH with dural penetration between 1990 and 2008 were retrospectively reviewed. The inclusion criterion was a CT scan available for review. Patients declared brain dead on presentation were excluded, which yielded a series of 119 patients. Statistical analysis was performed using a logistic regression model. RESULTS: Fifty-eight (49%) of the 119 patients died. Twenty-three patients (19%) had a favorable outcome defined as a 6-month Glasgow Outcome Scale (GOS) score of moderate disability or good recovery, 35 (29%) had a poor outcome (GOS of persistent vegetative state or severe disability), and 3 (3%) were lost to follow-up. Significant prognostic factors for mortality were age older than 35 years, nonreactive pupils, bullet trajectory of bihemispheric (excluding bifrontal), and posterior fossa involvement compared with unihemispheric and bifrontal. Factors that were moderately associated with higher mortality included intracranial pressure (ICP) above 20 mm Hg and Glasgow Coma Scale (GCS) score at presentation of 3 or 4. Upon multivariate analysis, the significant factors for mortality were bullet trajectory and pupillary response. Variables found to be significant for good functional outcome were admission GCS score greater than or equal to 5, pupillary reactivity, and bullet trajectory of unihemispheric or bifrontal. Factors moderately associated with good outcome included age of 35 years or younger, initial ICP 20 mm Hg or lower, and lack of transventricular trajectory. In the multivariate analysis, significant factors for good functional outcome were bullet trajectory and pupillary response, with age moderately associated with improved functional outcomes. The authors also propose a scoring system to estimate survival and functional outcome. CONCLUSIONS: Age, pupils, GCS score, and bullet trajectory on CT scan can be used to determine likelihood of survival and good functional outcome. The authors advocate assessing patients based on these parameters rather than pronouncing a poor prognosis and withholding aggressive resuscitation based upon low GCS score alone.

Osteosarcoma of the cranial vault and skull base in pediatric patients.

Cranial osteosarcoma is very rare in children, rendering the development of optimal treatment algorithms challenging. The authors present 3 cases of pediatric cranial osteosarcoma: a primary calvarial tumor, a cranial metastasis, and a primary osteosarcoma of the cranial base. A review of the literature demonstrates significant variation in the management of cranial osteosarcomas and the outcome for patients with these tumors. This series and literature review is presented to improve the understanding of pediatric cranial osteosarcoma and to reinforce the importance of maximal resection in optimizing outcome.

Iliac screw placement in neuromuscular scoliosis using anatomical landmarks and uniplanar anteroposterior fluoroscopic imaging with postoperative CT confirmation.

OBJECT: Neuromuscular scoliosis is a challenging pathology to treat. Surgical correction can involve long fusion constructs extending to the pelvis. The deformity inherent in these patients makes it difficult to obtain adequate lateral intraoperative radiographs for traditional image-guided placement of iliac screws. METHODS: A clinical and radiographic assessment of 14 patients with neuromuscular spinal deformity was conducted. From 2007 to 2013, 12 of these patients (mean age 14.25 years, range 10-20 years) underwent long spinal instrumentation (mean 15 levels, range 10-18 levels) and fusion to the pelvis, and 2 underwent placement of a growing rod construct with iliac screw placement at a single institution. The average length of follow-up was 33.7 months (range 6-64 months). Iliac screws were placed after identifying the posterior superior iliac spine and using only anteroposterior fluoroscopy (view of the inlet of the pelvis), rather than the technique of direct palpation of the sciatic notch. The accuracy of iliac screw placement was assessed with routine postoperative CT. RESULTS: A total of 12 patients had 24 screws placed as part of a long-segment fusion to the pelvis, and 2 patients had two iliac screws placed as part of a growing rod construct for neuromuscular scoliosis. There were no iliac screw misplacements, and no complications directly related to the technique of iliac screw placement. For cases of definitive fusion (n = 12), the average coronal Cobb angle of patients with neuromuscular spinal deformity measured 62° before surgery and 44.3° immediately after surgery. The average preoperative thoracic kyphosis and lumbar sagittal lordosis measured 37.3° and 60.7°, respectively. Immediately after surgery, the thoracic and lumbar angles measured 30° and 41.1°, respectively. At last follow-up, the average coronal Cobb angle was maintained at 45.1°, and the thoracic and lumbar sagittal angles were maintained at 32.8° and 45.3°, respectively. CONCLUSIONS: A less invasive technique for iliac screw placement can be performed safely with a low likelihood of screw misplacement. This technique offers the biomechanical advantages of iliac fixation without the soft tissue exposure typically needed for safe screw insertion. The technique relies on identification of the posterior superior iliac spine and high quality anteroposterior fluoroscopic imaging for a view of the pelvic inlet.

Rh-BMP-2 for L5-S1 arthrodesis in long fusions to the pelvis for neuromuscular spinal deformity in the pediatric age group: analysis of 11 patients.

PURPOSE: Neuromuscular scoliosis is a challenging pathology to treat with high incidence of complications and failure of surgical fusion. Surgical correction can entail long fusion constructs extending to the pelvis. We report our experience in the use of bone morphogenetic protein (BMP) to augment L5-S1 arthrodesis in long segment fusions in pediatric patients with neuromuscular scoliosis. METHODS: Retrospective review of 11 pediatric patients with neuromuscular spinal deformity (mean, age 13.7 years; range, 10-20 years) who underwent long (mean, 15 levels; range, 10-18 levels) spinal instrumentation and fusion to the pelvis at a single institution from 2007 to 2012 with an average follow-up of 34 months (range, 11-62 months). RESULTS: Of the 11 patients, one had pseudoarthrosis at L5-S1. The average coronal Cobb angle measured 59° before surgery and 42° immediately after surgery. The average preoperative thoracic kyphosis and lumbar sagittal lordosis measured 34 and 59°, respectively. Immediately after surgery, the thoracic and lumbar angles measured 28 and 39°, respectively. At last follow-up, the average coronal Cobb angle was maintained at 43° and the thoracic and lumbar sagittal angles were 28 and 44°, respectively. An average of 14.2 mg of recombinant human bone morphogenetic protein-2 (rh-BMP-2) was used for each case. CONCLUSIONS: L5-S1 arthrodesis may be effectively achieved in long fusions for pediatric neuromuscular spinal deformity with posterolateral fusion supplemented with rh-BMP-2. This surgical strategy may be associated with lower complication rates, decreased blood loss, and shorter operative times than circumferential fusion, which is particularly important in this complex fragile patient population.

Spondylolysis of C-2 in children 3 years of age or younger: clinical presentation, radiographic findings, management, and outcomes with a minimum 12-month follow-up.

OBJECT: Cervical spondylolysis is a rare condition that results from a pars interarticularis defect. The C-6 level is the most frequently involved site in the cervical spine. Its clinical presentations range from incidental radiographic findings to neck pain and, rarely, neurological deficits. Although 150 patients with subaxial cervical spondylolysis have been reported, a mere 24 adult and pediatric patients with C-2 spondylolysis have been described. The long-term outcomes of very young children with bilateral C-2 spondylolysis are of great interest, yet only a few longitudinal studies exist. METHODS: The authors retrospectively reviewed 5 cases of bilateral C-2 spondylolysis at Texas Children's Hospital and Riley Children's Hospital; these were combined with 5 other cases in the literature, yielding a total of 10 patients. Data regarding the patients' age, sex, C2-3 angulation and displacement, associated spine anomalies, neurological deficits, treatment, and most recent follow-up were recorded. RESULTS: The patients' ages ranged from 3 to 36 months (mean 12.9 months). There were 6 boys and 4 girls. The C2-3 angulation, displacement, and width of pars defect were measured when available. The mean C2-3 angulation was 9.5° (range 1-34°), the mean C2-3 displacement was 4.78 mm (range 1.1-10.8 mm), and the mean width of the pars defect was 4.16 mm (range 0.9-7 mm). One patient developed myelopathy and spinal cord injury. All 10 of the patients were treated initially with conservative therapy: 3 with close observation alone, 1 with a rigid cervical collar, 4 with a Minerva jacket, 1 with a sternal-occipital-mandibular immobilizer, and 1 with a halo vest. Three patients ultimately underwent surgery for internal fixation due to progressive instability or development of neurological symptoms. All patients were neurologically intact at the last follow-up (mean 44.3 months, range 14-120 months). CONCLUSIONS: Based on the literature and the authors' own experience, they conclude that most very young children with C-2 spondylolysis remain neurologically intact and maintain stability in long-term follow-up despite the bony defect. This defect is often an asymptomatic incidental finding and may be managed conservatively. More aggressive therapy including surgery is indicated for those patients with a neurological deficit from spinal cord compromise secondary to stenosis and local C-2 kyphosis, progressive deformity, or worsening C2-3 instability.

Cervicothoracic nonterminal myelocystocele with mature teratoma.

Nonterminal myelocystocele is a rare type of spinal dysraphism characterized by a closed defect with an underlying CSF-filled cyst, either contiguous with the central spinal canal or attached to the spinal cord by a fibrovascular stalk. The authors report the unusual case of a neonate with a prenatal diagnosis of cervicothoracic nonterminal myelocystocele who underwent postnatal surgical untethering of the lesion. Pathological analysis of the excised lesion revealed neuroglial tissue with an ependymal lining associated with a mature teratoma. Three months after surgery, the patient has normal lower-extremity sensorimotor function and no evidence of bowel or bladder dysfunction. To the best of the authors' knowledge, this is the first report of a patient with a nonterminal myelocystocele found to have an associated mature teratoma.

Disseminated intracranial juvenile xanthogranulomatosis in a neonate without cutaneous lesions.

Juvenile xanthogranuloma (JXG) is a rare disease that is part of a spectrum of histiocytic dendritic cell disorders. The authors report an unusual case of a 6-week-old male who presented with seizures. Neuroimaging revealed disseminated intracranial disease involving the optic apparatus, basal ganglia, lateral ventricles, and brainstem. The patient did not have any cutaneous lesions or evidence of extracranial disease. The patient underwent open biopsy of a large right midbrain lesion; pathology was consistent with JXG. He underwent postoperative chemotherapy and is doing well 7 months after surgery with regression of the intracranial lesions. To the best of the authors' knowledge, this is the first report of a neonate with disseminated intracranial JXG without cutaneous stigmata.

Routine sectioning of the C2 nerve root and ganglion for C1 lateral mass screw placement in children: surgical and functional outcomes.

PURPOSE: Adult studies have shown that sectioning the C2 nerve root and ganglion may facilitate placement of C1 lateral mass screws and lead to decreased operative time and blood loss. We report the functional outcomes and complications following routine sectioning of the C2 nerve root and ganglion, which have not been reported in pediatric patients. METHODS: Fifteen consecutive pediatric patients underwent C1 lateral mass screw insertion and bilateral C2 nerve root and ganglion sectioning. Clinical and radiographic assessments were performed at follow-up. Numbness in the C2 distribution and/or occipital neuralgia, operative times, estimated blood loss (EBL), length of stay (LOS), and complications were recorded. RESULTS: Average follow-up time was 35.7 months. Overall mean operative time was 250.5 min, LOS was 8.46 days, and EBL was 337 cc. When considering only atlantoaxial fusions, mean operative time was 180.7 min and EBL was 97.1 cc. There were no intraoperative complications, and no patient reported new onset occipital neuralgia or numbness in the C2 distribution that would interfere with daily living. Of the patients, 93 % achieved Lenke fusion grade A; one achieved Lenke fusion grade B. CONCLUSIONS: Routine C2 nerve root sectioning and ganglionectomy enhanced surgical exposure of the C1 lateral mass and C1-2 facet joint, potentially maximizing fusion rate and minimizing intraoperative complications. This technique may yield favorable operative times, EBL, and LOS in children undergoing C1 lateral mass screw insertion without negatively affecting functional outcome.

Outcomes of instrumented fusion in the pediatric cervical spine.

OBJECT: The most common cause of cervical spine arthrodesis in the pediatric population is instability related to congenital or traumatic pathology. Instrumenting the cervical spine can be challenging given smaller anatomical structures, less ossified bone, and future growth potential and development. Studies in adult patients have suggested that using screw constructs results in improved outcomes with lower rates of instrumentation failure. However, the pediatric literature is limited to small retrospective series. Based on a review of the literature and their own patient series, the authors report that instrumenting the pediatric cervical spine with screw constructs may be safer and more effective than using wiring techniques. METHODS: The authors reviewed the existing pediatric cervical spine arthrodesis literature and contributed 31 of their own cases from September 1, 2007, to January 1, 2011. They reviewed 204 abstracts from January 1, 1966, to December 31, 2010, and 80 manuscripts with 883 total patients were included in the review. They recorded demographic, radiographic, and outcomes data-as well as surgical details-with a focus on fusion rates and complications. Patients were then grouped into categories based upon the procedure performed: 1) patients who underwent fusions bridging the occipitocervical junction and 2) patients who underwent fusion of the cervical spine that did not include the occiput, thus including atlantoaxial and subaxial fusions. Patients were further subdivided according to the type of instrumentation used-some had posterior cervical fusion with wiring (with or without rod implantation); others had posterior cervical fusion with screws. RESULTS: The entire series comprised 914 patients with a mean age of 8.30 years. Congenital abnormalities were encountered most often (in 55% of cases), and patients had a mean follow-up of 32.5 months. From the entire cohort, 242 patients (26%) experienced postsurgical complications, and 50 patients (5%) had multiple complications. The overall fusion rate was 94.4%. For occipitocervical fusions (N = 285), both screw and wiring groups had very high fusion rates (99% and 95%, respectively, p = 0.08). However, wiring was associated with a higher complication rate. From a sample of 252 patients, 14% of those treated with screw instrumentation had complications, compared with 50% of patients treated with wiring (p < 0.05). In cervical fusions not involving the occipitocervical junction (N = 181), screw constructs had a 99% fusion rate, whereas wire instrumentation only had an 83% fusion rate (p < 0.05). Similarly, patients who underwent screw fixation had a lower complication profile (15%) when compared with those treated with wiring constructs (54%, p < 0.05). CONCLUSIONS: The results of this study are limited by variations in construct design, use of orthoses, follow-up duration, and newer adjuvant products promoting fusions. However, a literature review and the authors' own series of pediatric cases suggest that instrumentation of the cervical spine in children may be safer and more efficacious using screw constructs rather than wiring techniques.

Complications of occipital screw placement for occipitocervical fusion in children.

OBJECT: Occipitocervical stabilization in the pediatric age group remains a challenge because of the regional anatomy, poor occipital bone purchase, and, in some instances, significant thinning of the occipital bone. Multiple bicortical fixation points to the occipital bone may be required to increase construct rigidity. The authors evaluated the complications of bicortical occipital screw placement in children with occipital fusion constructs. METHODS: The records of 20 consecutive pediatric patients who had undergone occipitocervical fusion between September 1, 2007, and November 30, 2010, at Texas Children's Hospital were reviewed. RESULTS: The patients consisted of 10 girls and 10 boys, ranging in age from 10 months to 16 years (mean ± SD, 7.7 ± 5.1 years). Two patients were lost to follow-up, 2 died for reasons unrelated to the surgery, and the remaining patients had at least 3 months of follow-up (mean 14 ± 11.8 months) with evaluation via dynamic radiography and CT. Four patients experienced 8 complications: 2 CSF leaks, 2 vigorous venous bleedings, worsening of quadriparesis, wound infection, radiographic pseudarthrosis, and transient dysphagia. Among 114 screws, there were 2 cases of intraoperative dural venous sinus injury and 2 cases of intraoperative CSF leakage, without clinical sequelae from these complications. Only 1 case of radiographic pseudarthrosis was identified in a patient with skeletal dysplasia and a prior failed C1-2 posterior arthrodesis. There were no difficulties with wound healing because of prominent occipital instrumentation, and there was only 1 wound infection. CONCLUSIONS: Data in this report confirm that including bicortical occipital screw placement in occipitocervical constructs in children may result in a high fusion rate but at the cost of a notable complication rate.