Penetrating orbitocranial injury to the sella: case report and review of the literature.

UNLABELLED: A 39-year-old woman sustained a self-inflicted transorbital penetrating injury that resulted in direct pituitary injury with hypopituitarism and decreased vision in the opposite eye. Several hormone deficiencies were detected. Even though this patient did not develop any other complications from her injury (abscess, cerebrospinal fluid fistula or pseudoaneurysm), after two years of follow-up no recovery of pituitary or visual function has occurred. CONCLUSION: From our experience in this case, we propose a conservative multidisciplinary approach when dealing with this type of lesion. Broad spectrum antibiotic coverage and early detection and replacement of any hormone deficiency should be instituted.

Occipito-atlantal dislocation: an uncommon case of cervical spine injury.

Occipito-atlantal dislocation (OAD) is a rare but often lethal type of spinal injury that can be found in up to 35% of traffic fatalities. Improved pre-hospital care, diagnosis, and immobilization of these patients have led to an increase in reported cases of survivors. Significant ligamentous disruption in OAD results in craniocervical instability. While the vast majority of patients will not survive, those who do present with a wide variety of neurological findings ranging from no deficit to quadriparesis with cranial nerve palsies. When the appropriate landmarks can be identified OAD can be identified on plain lateral cervical spine radiographs by using the basion-axial interval and basion-dental interval (or BAI-BDI) method. When this measurement is normal, but prevertebral soft tissue swelling is present, additional imaging such as magnetic resonance imaging and computerized tomography are useful to aid in making the diagnosis. Once this is established, immobilization followed by occipitocervical fusion is recommended. We present a case of a patient who survived for a brief period of time after being hit by a vehicle and who was found to have OAD. We discuss the pathophysiology, imaging, clinical findings, and treatment for this type of spinal injury.

Comparison of allograft bone and titanium cages for vertebral body replacement in the thoracolumbar spine: a biomechanical study.

BACKGROUND: When an anterior approach to repair a burst fracture is indicated, several devices can be used to restore spinal stability (eg, bone graft, free-standing titanium cage, and expandable titanium cage). OBJECTIVE: We compare the biomechanical stability and prices of each of these systems. MATERIALS AND METHODS: Eight fresh human cadaver T11 through L3 vertebral specimens were harvested and cleaned of soft tissues. T11-T12 and L2-L3 were fixed by screws. The fixed ends were then set in automotive body filler (Bondo). The prepared specimens were tested in the Biaxial Instron tester (8874, Norwood, MA) after a sequence of the following: intact, after the creation of an anterior corpectomy at L1, and after insertion of both of the 2 different titanium cages and the fibular graft. A titanium screw-and-plate anterolateral system was used to secure the construct (VANTAGE, Medtronic Sofamor Danek, Memphis, TN). The conditions of displacement testing were as follows: rotation (+/- 3.5 degrees ), flexion and extension, and left and right bending (+/- 3.5 mm). For each mode of testing, the stiffness was calculated. RESULTS: The stiffness data, when statistically analyzed by repeated-measures analysis of variance (at P = .05 and power > 0.9), indicated no significant differences among these devices. CONCLUSION: On the basis of this biomechanical study, the stiffness of the fibular graft was similar to that of the other metallic devices in this cadaver model.

Accuracy of pedicle screw placement for lumbar fusion using anatomic landmarks versus open laminectomy: a comparison of two surgical techniques in cadaveric specimens.

OBJECTIVE: We determined whether the accuracy of lumbar pedicle screw placement is optimized by performing a laminectomy before screw placement with screw entry point and trajectory being guided by pedicle visualization and palpation (Technique 1). This technique was compared with a technique using anatomic landmarks for pedicle screw placement (Technique 2). The biomechanical stability of the instrumented constructs, in the absence and presence of a laminectomy, was also compared. METHODS: Twelve L1-L3 specimens were harvested from fresh cadavers. The intact laminectomy and instrumented spines were biomechanically tested in flexion and extension, lateral bending, and axial rotation. Laminectomies were performed in six of the 12 specimens before pedicle screw placement using Technique 1. The remaining six specimens underwent pedicle screw and rod fixation using Technique 2. Computed tomographic images were obtained for all instrumented specimens. Deviation of the screws from the ideal entry point or trajectory was analyzed to quantitatively compare the two techniques. RESULTS: Computed tomographic analysis of the specimens showed that all screw placements were within the pedicles. Scatter plot analysis demonstrated that screws placed using Technique 2 were more likely to have the combination of entry points and trajectories medial to the ideal entry point and trajectory. Laminectomy did not weaken the final pedicle screw and rod-fixated constructs. CONCLUSION: All screw placements were grossly within the confines of the pedicles, regardless of technique, as evidenced by computed tomographic analysis. Furthermore, the anatomic landmark technique and the open laminectomy technique yielded biomechanically equivalent pedicle screw and rod-fixated constructs.

Augmentation of anterior lumbar interbody fusion with anterior pedicle screw fixation: demonstration of novel constructs and evaluation of biomechanical stability in cadaveric specimens.

OBJECTIVE: Anterior lumbar interbody fusion (ALIF) has proven effective for indications including discogenic back pain, nonunion, and instability. Current practice involves posterior pedicle screw augmentation of the ALIF procedure (ALIF-PPS). This approach requires intraoperative repositioning of the patient for percutaneous posterior pedicle screw placement. We have developed a novel technique in which the ALIF procedure is augmented with anterior pedicle screws (APS; ALIF-APS). In this study, we introduce this new technique and compare the biomechanical stability of the novel ALIF-APS with the current standard ALIF-PPS. METHODS: The technique was demonstrated in a cadaveric L4-S1 specimen using neuronavigation and fluoroscopy. Plain radiographs and computed tomographic scans of the construct were obtained. Twelve cadaveric spines (7 men and 5 women) from donors with an average age of 81 years (range, 64-93 yr) were then harvested from L4-S1. Six specimens were dedicated to ALIF-APS constructs, and the remaining six were dedicated to ALIF-PPS constructs. The specimens were then studied at L5-S1 in the following steps: 1) intact form, 2) after anterior discectomy, 3) after implantation of titanium cages (ALIF), and 4) after APS or PPS fixation in conjunction with the ALIF. Measurements were obtained in axial rotation and left and right lateral bending flexion-extension. Data were normalized by calculating the ratio of the stiffness of the instrumented to the intact spine. Statistical analyses were then performed on the data. RESULTS: Radiographs and computed tomographic scans of the construct showed accurate placement of the APS at L5 and S1. The normalized data showed that ALIF-APS and ALIF-PPS had approximately equal stability in axial rotation (1.17 +/- 0.43 versus 0.85 +/- 0.14), lateral bending (0.93 +/- 0.22 versus 0.95 +/- 0.16), and flexion- extension (0.77 +/- 0.13 versus 0.84 +/- 0.2). Paired t test analysis did not show a significant difference between the biomechanical stiffness of ALIF-APS and ALIF-PPS in axial rotation, lateral bending, and flexion-extension. CONCLUSION: We demonstrate a new technique in a cadaveric specimen whereby the ALIF procedure is augmented with APS fixation using neuronavigation and fluoroscopy. Biomechanical evaluation of the constructs suggests that the ALIF-APS has comparable stability with ALIF-PPS. APS augmentation of ALIF has potential advantages over the current standard ALIF-PPS because it can 1) eliminate the patient repositioning step, 2) minimize the total number of incisions and the total operative time, and 3) protect against dislocation of the ALIF interbody graft or cage. Work is in progress to develop a low-profile system for the novel APS constructs described here.