The treatment of unstable thoracic spine fractures with transpedicular screw instrumentation: a 3-year consecutive series.

STUDY DESIGN: The treatment of unstable thoracic spine fractures remains controversial. Theoretical biomechanical advantages of transpedicular screw fixation include three-column control of vertebral segments and fixation of a vertebral segment in the absence of intact posterior elements. Additionally, pedicle screw constructs may obviate the need for neural canal dissection and potential neural element impingement by intracanal instrumentation. A 3-year consecutive series was performed to evaluate the use of transpedicular screw fixation in the treatment of unstable thoracic spine injuries. OBJECTIVE: This study was performed to evaluate the efficacy of transpedicular screw fixation in the upper, middle, and lower thoracic spine. SUMMARY OF BACKGROUND DATA: The use of rod/hook and rod/wiring techniques has been evaluated in the treatment of thoracic spine injuries. To date, a study evaluating the safety and efficacy of pedicle screw instrumentation in the upper, middle, and lower thoracic spine has not been reported. METHODS: Thirty-two patients with 79 individual vertebral injury levels (T2-L1) treated with transpedicular spinal stabilization and bone fusion were evaluated during a 3-year consecutive series from 1998 to 2001. Patient charts, operative reports, preoperative and postoperative radiographs, computed tomography scans, and postoperative follow-up examinations and radiographs were reviewed from the time of surgery to final follow-up assessment. Radiographic measurements included: sagittal index, Gardner segmental kyphotic deformity, and compression percentage. RESULTS: A total of 252 pedicle screws were placed, of which 222 were placed in segments T2-L1. Clinical examination and plain radiographs were used to determine the presence of a solid fusion. Fracture healing and radiographic stabilization occurred at an average of 4.8 months after the initial operation. There were no reported cases of hardware failure, loss of reduction, or painful hardware removal. Two hundred fifty-two transpedicular screws were successfully placed without intraoperative complications. The mean preoperative sagittal index was 13.9 degrees, whereas the mean follow-up was 5.25 degrees (P < 0.001). The mean final correction of sagittal index achieved was 8.65 degrees, or a 62.2% improvement. The mean Gardner segmental kyphotic angle was 15.9 degrees, whereas the mean follow-up angle was 10.6 degrees (P < 0.0005). The mean compression percentage was 35.4, and at follow-up was 27.4 (P < 0.07). CONCLUSIONS: In carefully selected instances, pedicle screw fixation of upper, middle, and lower thoracic and upper thoracolumbar spinal injuries is a reliable and safe method of posterior spinal stabilization. Transpedicular screw fixation may offer superior three-column control in the absence of posterior element integrity and obviates the need for intracanal placement of hardware. Transpedicular instrumentation provides rigid fixation for upper, middle, and lower unstable thoracic spine injuries and produces early pain-free fusion results. These results provide evidence that with appropriate preoperative radiographic evaluation of pedicular size and orientation using computed tomography as well as radiograph assessment, transpedicular instrumentation is a safe and effective alternative in the treatment of unstable thoracic (T2-L1) spinal injuries.

Clinical protocol. Gene therapy of Canavan disease: AAV-2 vector for neurosurgical delivery of aspartoacylase gene (ASPA) to the human brain.

This clinical protocol describes virus-based gene transfer for Canavan disease, a childhood leukodystrophy. Canavan disease, also known as Van Bogaert-Bertrand disease, is a monogeneic, autosomal recessive disease in which the gene coding for the enzyme aspartoacylase (ASPA) is defective. The lack of functional enzyme leads to an increase in the central nervous system of the substrate molecule, N-acetyl-aspartate (NAA), which impairs normal myelination and results in spongiform degeneration of the brain. No effective treatment currently exists; however, virus-based gene transfer has the potential to arrest or reverse the course of this otherwise fatal condition. This procedure involves neurosurgical administration of approximately 900 billion genomic particles (approximately 10 billion infectious particles) of recombinant adeno-associated virus (AAV) containing the aspartoacylase gene (ASPA) directly to affected regions of the brain in each of 21 patients with Canavan disease. Pre- and post-delivery assessments include a battery of noninvasive biochemical, radiological, and neurological tests. This gene transfer study represents the first clinical use of AAV in the human brain and the first instance of viral gene transfer for a neurodegenerative disease.