Because of testing methodology, the rib cage accounted for a greater percentage of thoracic stability than previously estimated. Different rib cage structures resisted motion in different loading planes.

The objective of this study was to investigate the diagnostic value of serum tau protein in determining the severity of traumatic brain injury in patients with mild traumatic brain injury (mTBI) and high-risk patients. Adult patients who presented to our emergency department (ED) with mTBI over 1 year were prospectively enrolled. Patients underwent cranial computed tomography (CT) and were subdivided into high- and low-risk groups, according to the probability of resultant intracranial injury. Serum tau levels of 60 patients and 20 healthy volunteers, who served as a control group, were measured. The mean age of the 60 patients (45 males, 15 females) was 32.5 years (range, 15-66 y). Mean Glasgow Coma Scale (GCS) score was 14+/-0.6. CT scans demonstrated intracranial injury in 11 patients (18.3%) and depressed fracture in 4 patients (6.7%). Serum tau levels of patients (188+/-210 pg/mL), compared with those of controls (86+/-48 pg/mL), were relatively higher; however, differences were not statistically significant (P=.445). Also, serum tau levels of high-risk patients (307+/-246 pg/mL) were significantly higher than those of low-risk patients (77+/-61 pg/mL) (P=.001). A total of 48 patients (80%) were accessible for follow-up after 6 months. Postconcussive syndrome was observed in 8 patients, 5 of whom had serum tau protein levels that were higher than those of the other 3 patients. However, no statistically significant difference was observed (P>.05). Investigators of the present study noted that serum tau levels in patients with mTBI were increased. Therefore, it is believed that this biomarker may prove helpful in identifying high-risk patients with mTBI. However, additional studies are needed to establish the diagnostic value of serum tau in detecting traumatic brain injury in patients with mTBI.

MR imaging can be helpful in revealing DAI lesions in patients with normal CT scan findings after MTBI. FLAIR, GRE and DW sequences are superior to conventional spin-echo images in detecting DAI lesions.

✓There is growing evidence to suggest that pregnancy may increase the risk of hemorrhage from cavernous malformations (CMs). In the present case, a 21-year-old primigravida was admitted to the authors' neurosurgical service after a cesarean section. Three weeks before admission she had experienced rapidly progressive bilateral lower-extremity paresthesias. Spinal magnetic resonance (MR) imaging revealed the presence of an intramedullary thoracic lesion. On T2-weighted MR images, heterogeneous signal intensity with a rim of decreased intensity was demonstrated in the spine. The mass was successfully resected, and 1 year later the patient's symptoms had resolved completely. This is the fourth reported case of a spinal intramedullary CM that became symptomatic during pregnancy. The pathogenesis and management of this entity are reviewed.

A 53-year-old woman presented with a rare case of cavernous hemangioma of the frontal bone manifesting as right frontal stabbing headache and local swelling. Computed tomography revealed an extensive, well-defined, radiolucent, osteolytic lesion in the right frontal bone. The inner and outer tables of the skull were eroded and the lesion had compressed the brain parenchyma. Right frontal craniotomy was performed, and the lesion with a 1 cm-wide margin of surrounding uninvolved bone was removed. The defect was reconstructed with titanium mesh. The patient did well after the operation. The cosmetic results were satisfactory and follow up at 6 months post-surgery revealed no recurrence.

Object An experiment was performed to study the limits of the ability of screws designed to center themselves in the pedicle during insertion, and to study whether straight-ahead versus inward screw insertion trajectories differ in their resistance to pullout. Methods Forty-nine human cadaveric lumbar vertebrae were studied. Pedicle screws were inserted in trajectories starting 0°, 10°, 20°, or 30° from the optimal trajectory, either medially or laterally misdirected. The surgeon then inserted the screw with forward thrust but without resisting the screw's tendency to reorient its own trajectory during insertion. On the opposite pedicle, a control screw was inserted with the more standard inward-angled anatomical trajectory and insertion point. Cortical wall violation during insertion was recorded. Screws were then pulled out at a constant displacement rate while ultimate strength was recorded. Results Lateral misdirection as small as 10° was likely to lead to cortical wall violation (3 of 7 violations). Conversely, medial misdirection usually resulted in safe screw insertion (1 of 21 violations for 10°, 20°, or 30° medial misdirection). The resistance to pullout of screws inserted in a straight-ahead trajectory did not differ significantly from that of screws inserted along an inward trajectory (p = 0.68). Conclusions Self-tapping, self-drilling pedicle screws can redirect themselves to a much greater extent during medial than during lateral misdirection. The cortical wall is more likely to be violated laterally than medially. The strength of straight-ahead and inward trajectories was equivalent.

Posterior fixation at L5-S1 using the low-profile screw-plate system offers stability, resistance to fatigue, and resistance to failure equivalent to fixation using a standard cantilevered pedicle screw-rod system.

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