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

OBJECTIVEThe 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.METHODSThe 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.RESULTSThe 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%).CONCLUSIONSPediatric 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.

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.

Solid variant of aneurysmal bone cyst of the thoracic spine: a case report.

INTRODUCTION: The solid variant of aneurysmal bone cyst is rare, and only 13 cases involving the spine have been reported to date, including seven in the thoracic vertebrae. The diagnosis is difficult to secure radiographically before biopsy or surgery. CASE REPORT: An 18-year-old Hispanic man presented to our facility with a one-year history of left chest pain without any significant neurological deficits. An MRI scan demonstrated a 6 cm diameter enhancing multi-cystic mass centered at the T6 vertebral body with involvement of the left proximal sixth rib and extension into the pleural cavity; the spinal cord was severely compressed with evidence of abnormal T2 signal changes. Our patient was taken to the operating room for a total spondylectomy of T6 with resection of the left sixth rib from a single-stage posterior-only approach. The vertebral column was reconstructed in a 360° manner with an expandable titanium cage and pedicle screw fixation. Histologically, the resected specimen showed predominant solid fibroblastic proliferation, with minor foci of reactive osteoid formation, an area of osteoclastic-like giant cells, and cyst-like areas filled with erythrocytes and focal hemorrhage, consistent with a predominantly solid variant of aneurysmal bone cyst. At 16 months after surgery, our patient remains neurologically intact with resolution of his chest and back pain. CONCLUSIONS: Because of its rarity, location, and radical treatment approach, we considered this case worthy of reporting. The solid variant of aneurysmal bone cyst is difficult to diagnose radiologically before biopsy or surgery, and we hope to remind other physicians that it should be included in the differential diagnosis of any lytic expansile destructive lesion of the spine.

Vacuum-assisted en bloc resection of large convexity meningiomas. Technical note.

Convexity meningiomas are common tumors encountered by neurosurgeons. Retracting, grasping, and mobilizing large convexity meningiomas can be difficult and awkward as well as place unwanted forces on surrounding neurovascular structures. The authors present a safe alternative to traditional retraction and manipulation methods by using a modified bulb syringe connected to standard surgical suction to function as a vacuum retractor. This technique allows for rapid, safe, en bloc resection of large convexity meningiomas with little to no pressure on the surrounding brain. The authors present an illustrative case and describe and discuss the technique.

Low-grade myofibroblastic sarcoma of the sacrum.

Myofibroblastic tumors are soft-tissue neoplasms arising from myofibroblasts, ubiquitous cells sharing ultrastructural features of muscular and fibroblastic cells. Vasudev and Harris described a malignant counterpart of these benign tumors in 1978. Most reported cases of myofibroblastic sarcoma have arisen in the head and neck region and the soft tissues of the extremities. To the best of the authors' knowledge, there have been only 8 previous reports on primary myofibroblastic sarcoma of the bone. The authors report a new case of this rare tumor affecting the sacrum and ilium of a 15-year-old girl and discuss the role of total sacrectomy and lumbopelvic reconstruction for treatment of this disease.

Video-assisted thorascopic repair of a subarachnoid-pleural fistula in a child after thoracic tumor resection: technical note.

STUDY DESIGN: Technical report. OBJECTIVE: To describe a minimally invasive surgical approach for the obliteration of a subarachnoid-pleural fistula in a 4-year-old child after resection of an intrathoracic ganglioneuroma. SUMMARY OF BACKGROUND DATA: Development of a subarachnoid-pleural fistula has been reported after thoracotomy for lung, chest wall, and spinal tumors, when an iatrogenic meningeal laceration results in establishing communication between the spinal subarachnoid space and the pleural cavity. METHODS: Review of a single case in which video-assisted thorascopic surgery (VATS) was used to deposit fibrin glue and to suture a pleural allograft. Literature review was performed to document other options to treat subarachnoid-pleural cerebrospinal fluid (CSF) fistula. RESULTS: At 10 months after VATS repair, the CSF fistula has remained closed. CONCLUSION: VATS technique should be considered for a safe, efficacious, and durable CSF leak repair and as an alternative to open thoracotomy in the pediatric age group.

Right ventricular infundibulum sparing (RVIS) tetralogy of fallot repair: a review of over 300 patients.

OBJECTIVE: The natural history of standard (large, transmural right ventriculotomy) repair of tetralogy of Fallot (TOF) is associated with a concerning incidence of right ventricular (RV) failure and reoperation. We believe preserving the infundibulum using a TOF repair method with a mini-(<5 mm) or no ventricular incision optimizes RV function and confers long-term benefit. Over the past 13 years, we have uniformly applied this RV infundibulum sparing (RVIS) strategy. METHODS: Using a retrospective cohort study design, 304 TOF patients who underwent the RVIS strategy (July 1995-June 2008) were reviewed. Median weight and age at repair: 8 kg (3-62 kg) and 9 months (2 days-23 years). Seventeen percent (51) of patients required a systemic-to-pulmonary artery shunt. RESULTS: Ninety-nine percent of patients had a mini- 73% (222) or no 26% (79) ventricular incision. Postoperative morbidity included arrhythmias 3% (10), postoperative bleeding 2% (7), temporary renal failure 1% (3), and neurologic injury <1% (2). Thirty-day survival was 99.7%. Overall 1 and 7-year Kaplan-Meier survivals were 97% and 96%. In nonsyndromic children, only 1 patient has died in the RVIS strategy. A total of 3.2% (10) of patients had reoperations. Twenty-one percent (65/304) of patients have been followed for >7 years (median: 8.5 years). None of them have severe dilation, > mild RV outflow obstruction, an arrhythmia, or a pacemaker/AICD. Ninety-five percent of these patients have normal RV function; 3 (4.6%) had mild dysfunction. This cohort has excellent exercise tolerance (MaxVO2 (mean): 41 ± 12 mL/kg/min). CONCLUSION: The RVIS strategy has allowed morbidity, mortality, and reoperation rates to be minimized. Midterm results suggest that RVIS does appear to preserve RV function. Longer term follow-up will be essential in establishing if the RVIS strategy can change the natural history of repaired TOF.

Transient selective downward gaze paralysis complicating posterior fossa tumor resection in children. Report of 2 cases.

Selective downward gaze paralysis has not previously been described as a complication after posterior fossa operations in children. The authors found downgaze palsy to be a transient complication after resection of large pediatric posterior fossa midline tumors reaching the aqueduct of Sylvius. They reviewed the cases of 2 children with large posterior fossa midline tumors who underwent resection via an inferior transventricular approach. They developed a hypothetical scheme to account for downward gaze paralysis based on anatomy and insight gained from experimental studies. The authors describe potential risk factors for developing transient selective downward gaze paralysis with the hope of making more pediatric neurosurgeons aware of this complication following removal of lesions around the mesencephalic periaqueductal gray matter. Recognition and understanding of downward gaze palsy after posterior fossa surgery should improve preoperative counseling and promote postoperative family coping.

Use of axial and subaxial translaminar screw fixation in the management of upper cervical spinal instability in a series of 7 children.

OBJECTIVE: The management of upper cervical spinal instability in children continues to represent a technical challenge. Traditionally, a number of wiring techniques followed by halo orthosis have been applied; however, they have been associated with a high rate of nonunion and poor tolerance for the halo. Alternatively, C1-C2 transarticular screws and C2 pars/pedicle screws allow more rigid fixation, but they are technically demanding and associated with vertebral artery injuries. Recently, C2 translaminar screws have been added to the armamentarium of the pediatric spine surgeon as a technically simple and biomechanically efficient method of fixation. However, subaxial translaminar screws have not been described in the pediatric population. We describe our experience with axial and subaxial translaminar screws in 7 pediatric patients. METHODS: Seven pediatric patients with the diagnosis of upper cervical spinal instability required surgical fixation (age, 19 months-14 years; sex, 4 boys and 3 girls; follow-up, 4-21 months; etiology, trauma [3 patients], os odontoideum/os terminale [2 patients], hypoplastic dens [2 patients]). All patients underwent axial and/or subaxial translaminar screw insertion. Iliac crest bone graft was used for fusion in 4 patients; bone morphogenic protein and cancellous morselized allograft was used for fusion in 3 patients. A rigid cervical collar was applied for 12 weeks postoperatively in all cases. No intraoperative image guidance was used for insertion of the translaminar screws. RESULTS: All patients had a postoperative computed tomographic scan. Two patients underwent placement of bilateral crossing C2 translaminar screws. Two patients had subaxial translaminar screw placement at C3 and the upper thoracic spine, respectively. Hybrid constructs (a C2 translaminar screw combined with a C2 pars screw) were incorporated in 3 patients. No patients were found to have a breach of the ventral laminar cortex. All patients achieved solid fusion. One patient had a perioperative complication: prolonged dysphagia probably related to C1 lateral mass screw insertion rather than C2 translaminar screw placement. CONCLUSION: To our knowledge, this report represents the only series of pediatric patients treated with axial and subaxial translaminar screws. This series shows that axial and subaxial translaminar screw fixation is a viable option for upper cervical spinal fusion in children. The technique is safe and results in adequate fixation with high fusion rates and minimal complications.

Transtubular microendoscopic approach for resection of a choroidal arteriovenous malformation.

The authors describe the novel use of a table-mounted tubular retractor system (MetRx) originally designed for minimally invasive spine surgery, in the resection of an intraventricular arteriovenous malformation (AVM) in a 12-year-old child. The tubular retractor system may have several advantages over traditional Greenberg or Leyla retractors in selected intracranial procedures. In our case, the low-profile 4x22-mm tube and fixed table attachment offered excellent exposure of the trigone of the lateral ventricle where the choroidal AVM was located and from which it was completely resected. Immediate postoperative cerebral angiography confirmed that the entire AVM had been resected. The patient suffered no new neurological deficits as a result of the retractor system or the exposure that it afforded. Although the good clinical results of a single case cannot be directly compared with those obtained using other open techniques of intracranial surgery in larger series, microendoscopic surgery of the brain is an alternative to the other techniques and may be recommended as a time-saving, trauma-reducing procedure with the potential to improve postoperative outcomes.

Pneumothorax complicating "in-out-in" thoracic pedicle screw placement for kyphotic deformity correction in a child.

The authors describe a rare case of pneumothorax as a complication of thoracic pedicle screw placement in an 11-year-old girl undergoing posterior segmental instrumentation for a kyphotic deformity. Spontaneous pneumothorax after posterior fusion for adolescent idiopathic scoliosis has been reported in the orthopedic literature; however, to the best of the authors' knowledge, pneumothorax directly related to pedicle screw placement for spinal deformity has not been previously described. The authors discuss the anatomical and technical aspects leading to this complication and the lessons learned from it.