Biomechanical comparison of two different compression screws for the treatment of odontoid fractures in human dens axis specimen.

BACKGROUND: Lag screw osteosynthesis for odontoid fractures has a high rate of pseudoarthrosis, especially in elderly patients. Besides biomechanical properties of the different screw types, insufficient fragment compression or unnoticed screw stripping may be the main causing factors for this adverse event. The aim of the study was to compare two screws in clinical use with different design principles in terms of compression force and stability against screw stripping. METHODS: Twelve human cadaveric C2 vertebral bodies were considered. Bone density was determined. The specimens were matched according to bone density and randomly assigned to two experimental groups. An odontoid fracture was induced, which were fixed either with a 3.5 mm standard compression screw or with a 5 mm sleeve nut screw. Both screws are certified for the treatment of odontoid fractures. The bone samples were fixed in a measuring device. The screwdriver was driven mechanically. The tests were analyzed for peak interfragmentary compression and screw-in torque with a frequency of 20 Hz. FINDINGS: The maximum fragment compression was significantly higher with screw with sleeve nut at 346.13(SD ±72.35) N compared with classic compression screw at 162.68(SD ±114.13) N (p = 0.025). Screw stripping occurred significantly earlier in classic compression screw at 255.5(SD ±192.0)° rotation after reaching maximum compression than in screw with sleeve nut at 1005.2(SD ±341.1)° (p = 0.0039). INTERPRETATION: Screw with sleeve nut achieves greater fragment compression and is more robust to screw stripping compared to classic compression screw. Whether the better biomechanical properties lead to a reduction of pseudoarthrosis has to be proven in clinical studies.

Olfactory Groove Meningiomas: Comprehensive assessment between the different microsurgical transcranial approaches and the Endoscopic Endonasal Approaches, systematic review and metanalysis on behalf of the EANS skull base section.

•OGM surgery is much more complex than a simple debate of "from above or from below" (transcranial vs endoscopic).•Lateral Sub-frontal and Superior Interhemispheric seem the most effective, superior and versatile approaches for OGM.•Minimally Invasive Transcranial approaches showed no inferiority in OGM sized <4 â€‹cm.•Endoscopic Endonasal Approaches showed inferior results in surgical and in functional outcomes for OGM.

Biomechanical comparison of three different compression screws for treatment of odontoid fractures evaluation of a new screw design.

BACKGROUND: Lag screw osteosynthesis in odontoid fractures shows a high rate of pseudarthrosis. Biomechanical properties may play a role with insufficient fragment compression or unnoticed screw stripping. A biomechanical comparison of different constructed lag-screws was carried out and the biomechanical properties determined. METHODS: Two identical compression screws with different pilot holes (1.25 and 2.5 mm), a double-threaded screw and one sleeve-nut-screw were tested on artificial bone (Sawbone, densities 10-30pcf). Fragment compression and torque were continuously measured using thin-film force sensors (Flexiforce A201, Tekscan) and torque sensors (PCE-TM 80, PCE GmbH). FINDINGS: The lowest compression reached the double-threaded screw. Compression and sleeve-nut-screw achieved 214-298% and 325-546%, respectively, of the compression force of double-threaded-screw, depending on the test material. The pilot hole optimization led to a significant improvement in compression only in the densest test material. Screw stripping took place significantly later with increasing density of the test material on all screws. In compression screws this was done at a screw rotation of 180-270°, in sleeve nut screw at 270-720° and in double-threaded screws at 300-600° after reaching the maximum compression. INTERPRETATION: Double-threaded screw is robust against screw stripping, but achieves only low fragment compression. The classic compression screws achieve better compression, but are sensitive to screw stripping. Sleeve-nut screw is superior in compression and as robust as double-threaded screw against screw stripping. Whether the better biomechanical properties lead to a reduction in pseudarthrosis must be proven in clinical trials.

Prevalence of hypopituitarism after intracranial operations not directly associated with the pituitary gland.

BACKGROUND: Over the last few years, awareness and detection rates of hypopituitarism following traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) has steadily increased. Moreover, recent studies have found that a clinically relevant number of patients develop pituitary insufficiency after intracranial operations and radiation treatment for non-pituitary tumors. But, in a substantial portion of more than 40%, the hypopituitarism already exists before surgery. We sought to determine the frequency, pattern, and severity of endocrine disturbances using basal and advanced dynamic pituitary testing following non-pituitary intracranial procedures. METHODS: 51 patients (29 women, 22 men) with a mean age of 55 years (range of 20 to 75 years) underwent prospective evaluation of basal parameters and pituitary function testing (combined growth hormone releasing hormone (GHRH)/arginine test, insulin tolerance test (ITT), low dose adrenocorticotropic hormone (ACTH) test), performed 5 to 168 months (median 47.2 months) after intracranial operation (4 patients had additional radiation and 2 patients received additional radiation combined with chemotherapy). RESULTS: We discovered an overall rate of hypopituitarism with distinct magnitude in 64.7% (solitary in 45.1%, multiple in 19.6%, complete in 0%). Adrenocorticotropic hormone insufficiency was found in 51.0% (partial in 41.2%, complete in 9.8%) and growth hormone deficiency (GHD) occurred in 31.4% (partial in 25.5%, severe in 5.9%). Thyrotropic hormone deficiency was not identified. The frequency of hypogonadism was 9.1% in men. Pituitary deficits were associated with operations both in close proximity to the sella turcica and more distant regions (p = 0.91). Age (p = 0.76) and gender (p = 0.24) did not significantly differ across patients with versus those without hormonal deficiencies. Groups did not significantly differ across pathology and operation type (p = 0.07). CONCLUSION: Hypopituitarism occurs more frequently than expected in patients who have undergone neurosurgical intracranial procedures for conditions other then pituitary tumors or may already exists in a neurosurgical population before surgery. Pituitary function testing and adequate substitution may be warranted for neurosurgical patients with intracranial pathologies at least if unexplained symptoms like fatigue, weakness, altered mental activity, and decreased exercise tolerance are present.

Waterjet dissection versus ultrasonic aspiration in epilepsy surgery.

OBJECTIVE: Waterjet dissection is currently under close investigation in neurosurgery. Experimentally, precise brain parenchyma dissection with vessel preservation has been demonstrated. Clinically, the safety of the instrument has already been proved. However, precise data demonstrating that waterjet dissection indeed reduces surgical blood loss are still missing. METHODS: The authors applied the waterjet device in a prospective randomized study in comparison with the ultrasonic aspirator. Because there is little variability in the procedure, 30 patients with temporal lobe epilepsy receiving a tailored temporal lobe resection between December 1999 and October 2002 were selected for this study. Intraoperative vessel preservation, intraoperative blood loss, surgical complications, and epilepsy outcome were evaluated. All patients were followed at 3-month intervals. RESULTS: During surgery, both instruments were easy to handle. Only with the waterjet dissector, however, were even small intraparenchymal blood vessels preserved. Intraoperative blood loss was significantly reduced with the waterjet (mean, 70 +/- 46 ml) compared with the ultrasonic aspirator (mean, 121 +/- 48 ml). However, no difference in the necessity for blood transfusion occurred. No difference was observed with respect to operation time (238.6 +/- 37.0 min with the waterjet, 247.5 +/- 41.5 min with the ultrasonic aspirator), surgical complications, and outcome. CONCLUSION: The waterjet dissector enables a significant reduction of intraoperative blood loss in the investigated setting. However, further studies are needed to confirm these results with a larger number of patients. Studies also are needed to prove that the reduction of blood loss is of clinical relevance for the outcome of the patients.

Prognosis of gliomas in the 1970s and today.

The benefit of the current strategy for diagnosis (magnetic resonance, [MR] imaging) and treatment (surgery, chemotherapy, radiotherapy) of gliomas, in contrast to the standard treatment in use before MR imaging and the microsurgical era, has not yet been determined. A retrospective statistical analysis was performed for all patients with glioma who underwent surgery at a single institution between 1965 and 1974 (Group I, 88 patients) or 1986 and 1995 (Group II, 249 patients). There were no major differences in symptomatology, tumor localization, and number of surgical procedures. The mean time until tumor diagnosis was significantly shorter in Group II (Group I, 48 weeks; Group II, 19.5 weeks). Also, the mean time from initial symptoms to surgery was significantly shorter for high-grade gliomas in Group II (Group I, 16.3 weeks; Group II, 11.7 weeks). For high- as well as low-grade gliomas, there was a clear reduction of the perioperative morbidity and mortality rates in Group II. Nevertheless, for the postoperative duration of survival, no significant differences were demonstrated for high- or low-grade gliomas. Based on the results of this study, the perioperative morbidity and mortality rate as well as the time from diagnosis to treatment have been remarkably reduced within the last 30 years. Nevertheless, the overall prognosis for patients with gliomas has not changed from the 1970s until today. Thus, the introduction of modern diagnostic modalities and surgical procedures has not improved the outcome in patients with glioma. Further research to improve the treatment of this disease is urgently needed.

Neuronavigation and complication rate in epilepsy surgery.

The role of neuronavigation for complications in temporal lobe epilepsy surgery was evaluated. Thirty-seven patients operated on with neuronavigation (group N: 38 operations; mean age 33.9 years; etiology: cryptogenetic 31, symptomatic 7; lateralization: 22 right, 16 left) and 22 patients operated on without neuronavigation (group NN: 23 operations; mean age 29.7 years; etiology: cryptogenetic 9, symptomatic 14; lateralization: 13 right; 10 left) were analyzed. The minimal follow-up time was 2 years. There was a clear difference in the number of complications (N 7.9%; NN 21.7%), which consisted of hemiparesis (N: 1; NN: 2), cranial nerve palsy (N: 1; NN: 2), aphasia (N: 1; NN: 0), and postoperative infection (N: 0; NN: 1). In addition, there was a reduced need for temporal re-resection after intraoperative electrocorticography (N 30.6%; NN 47.1%). Operation time (N: 239+/-9.4 min; NN: 208+/-12.1 min), duration of postoperative in-hospital and in-ICU stay [N: 16.9+/-1.1 days (1.0+/-0.0 days); NN: 17.2+/-2.8 days (1.1+/-0.1 days)], extension of temporal lobe resection from polar (N: 41.2+/-1.5 cm; NN: 42.9+/-3.9 cm), and postoperative seizure frequency reduction (N 90.4%; NN 94.7%) were not different. Because of the trend towards a reduction of complications and re-resections after electrocorticography, the authors recommend neuronavigation despite its higher costs as an additional tool in epilepsy surgery.