Search

Background: The protective effectiveness of bicycle helmets has been demonstrated in several epidemiologic studies. However, the temple region is only minimally covered by most helmet models. Impact tests were performed on human cadavers to investigate whether current bicycle helmets are capable of preventing direct contact on the temporal area in side impacts., Methods: Lateral head impacts, corresponding to a force load of 15,000 N on an nonhelmeted head, were applied on 11 helmeted cadavers by a steel pendulum with a flat impact surface, and the contact between the impactor plate and the temporal and zygomatic area was investigated by means of paint transfer. In eight tests, a common design bicycle helmet was used, whereas in three tests the helmets provided larger temporal coverage (temporal helmet edge <10 mm above Frankfort plane). The skulls were inspected for fractures., Results: In seven of the eight tests with common design bicycle helmets, contact had occurred and in one of these a skull fracture was seen. The helmets with a larger temporal coverage consistently prevented such contact loading., Conclusions: The common designs of commercially available bicycle helmets do not prevent direct contact loading on the temporal and zygomatic arch region and this contact loading is potentially harmful. The present preliminary study strongly questions the effectiveness of these helmets in providing accurate protection of the temporal and zygomatic area.

Object: Endoscopy is a useful technique for obtaining biopsy samples of intraventricular tumors, and it offers the advantage of simultaneous treatment of obstructive hydrocephalus through endoscopic third ventriculostomy (ETV). Figures in the literature on the diagnostic yield of endoscopic biopsy, its complication rate, and the success rate of ETV in this context vary significantly. The authors performed a retrospective analysis of biopsy accuracy, complication rate, and success rate of ETV in a series of 31 endoscopic biopsy procedures., Methods: All data regarding tissue and cerebrospinal fluid sampling, endoscopy-related complications, procedures performed for hydrocephalus treatment, tissue diagnosis, and further management were reviewed. The accuracy of the biopsy findings was graded on a four-level scale: Level I, fully diagnostic; Level II, diagnostic with some reservation; Level III, pathological categorization problematic; and Level IV, not interpretable. Failure of ETV was defined as the need for any further operation for the treatment of hydrocephalus. Tissue diagnosis was graded as Level I or II in 23 cases. One Level I diagnosis differed from the diagnosis made following craniotomy. During the study period one patient underwent endoscopy without biopsy because the tumor could not be visualized. Consequently, the percentage of successful biopsies was 69% (22 of 32 endoscopic procedures). Complications occurred in six cases (19%), of which two (6%) were significant. Three patients (10%) suffered hemorrhagic complications. When combined with biopsy, the ETV procedure was successful in nine (64%) of 14 patients., Conclusions: Endoscopic biopsy of intraventricular tumors is a useful technique for establishing a tissue diagnosis and is associated with an acceptable complication rate. The biopsy does not affect the success rate of simultaneous ETV.

Skull fracture is a frequently observed type of severe head injury. Historically, a variety of impact test set-ups and techniques have been used for investigating skull fracture. The most frequently used are the free-fall technique, the guided fall or drop tower set-up and the piston-driven impactor set-up. This document proposes a new type of set-up for cadaver head impact testing which combines the strengths of the most frequently used techniques and devices. The set-up consists of two pendulums, which allow for a 1 degree of freedom rotational motion. The first pendulum is the impactor and is used to strike the blow. The head is attached to the second pendulum using a polyester resin. Local skull deformation and impact force are measured with a sample frequency of 65 kHz. From these data, absorbed energy until skull fracture is calculated. A set-up evaluation consisting of 14 frontal skull and head impact tests shows an accurate measurement of both force and local skull deformation until fracture of the skull. Simplified mechanical models are used to analyse the different impacting techniques from literature as well as the new proposed set-up. It is concluded that the proposed test set-up is able to accurately calculate the energy absorbed by the skull until fracture with an uncertainty interval of 10%. Second, it is concluded that skull fracture caused by blunt impact occurs before any significant motion of the head. The two-pendulum set-up is the first head impact device to allow a well-controlled measurement environment without altering the skull stress distribution.

Object: Based on data from primate experiments it is known that rotational acceleration in the sagittal plane and in a forward direction is most likely to produce acute subdural hematomas due to bridging vein rupture. For protection against these lesions, knowledge of rotational acceleration tolerance levels in humans is required. In the present study the authors analyze human tolerance levels for bridging vein rupture by performing head impact tests in cadavers., Methods: Ten unembalmed cadavers were subjected to 18 occipital impacts producing head rotation in the sagittal plane with varying rotational acceleration magnitudes and pulse durations. Rotational acceleration was calculated from the linear acceleration histories recorded by three uniaxial accelerometers mounted on the side of the head. Bridging vein ruptures were detected by injecting contrast dye into the superior sagittal sinus under fluoroscopy and by autopsy procedures. Bridging vein ruptures were produced in six head impact tests: one test with a pulse duration of 5.2 msec and a peak rotational acceleration of 13,411 rad/second2; three tests with a pulse duration between 7 and 8 msec and a peak rotational acceleration of 12,558, 10,607, and 8567 rad/second2; and two tests with a pulse duration longer than 10 msec and a peak rotational acceleration as low as 5267 rad/second2., Conclusions: This is the only cadaveric study of bridging vein rupture focused on short pulse durations, which are usually associated with falls. The data suggest a tolerance level of approximately 10,000 rad/second2 for pulse durations shorter than 10 msec, which seems to decrease for longer pulse durations.

Within the framework of a bicycle helmet research program, we have set up a database of bicycle accident victims, containing both accident and clinical data. The database consists of a consecutive series of 86 victims of bicycle accidents who underwent a neurosurgical intervention in our hospital between 1990 and 2000. Data were obtained from police files, medical records, computed tomography head scans and a patient questionnaire. In only three victims, the wearing of a helmet was documented. In this study, the head injuries are analysed and the relation between the different types of head injuries and outcome is assessed. Forty-four accidents were collisions with a motor vehicle and 42 accidents were falls. Most impacts occurred at the side (57%) or at the front (27%) of the head. The most frequent injuries were skull fractures (86%) and cerebral contusions (73%). Age was negatively correlated with outcome (P = 0.0002 ) and positively correlated with the number (P = 0.00002) and volume (P = 0.00005) of contusions and the presence of subdural haematomas (P = 0.000001). The injuries with the strongest negative effect on outcome were: subarachnoid haemorrhage (P = 0.000001), multiple (P = 0.000005) or large ( P 0.0007) contusions, subdural haematoma (P = 0.001) and brain swelling (P = 0.002). A significant coexistence of these four injuries was found. We hypothesise that in many patients the contusions may have been the primary injuries of this complex and should therefore be considered as a main injury determining outcome in this study. We believe that such findings may support a rational approach to optimising pedal cyclist head protection.

The aim of this work was to add to the body of data on the frequency and severity of degenerative radiographic findings at adjacent levels after anterior cervical interbody fusion and on their clinical impact and to contribute to the insights about their pathogenesis. One hundred eighty patients who were treated by anterior cervical interbody fusion and who had a follow-up of >60 months were clinically and radiologically examined by independent investigators. For all patients, the long-term Odom score was compared with the score as obtained 6 weeks after surgery. For myelopathic cases, both the late Nurick and the Odom score were compared with the initial postoperative situation. For the adjacent disc levels, a radiologic "degeneration score" was defined and assessed both initially and at long-term follow-up. At late follow-up after anterior cervical interbody fusion, additional radiologic degeneration at the adjacent disc levels was found in 92% of the cases, often reflecting a clinical deterioration. The severity of this additional degeneration correlated with the time interval since surgery. The similarity of progression to degeneration between younger trauma patients and older nontrauma patients suggests that both the biomechanical impact of the interbody fusion and the natural progression of pre-existing degenerative disease act as triggering factors for adjacent level degeneration.

Four human skulls were studied in order to determine the energy absorbed corresponding to a fracture due to quasi-static loading on the frontal bone. Using a dedicated experimental set up, the force-deformation characteristics of the specimens were recorded, calculating energy absorption. Mean values of 1975 +/- 703 N, 4.17 +/- 0.81 mm and 3.95 +/- 1.18 J were found for the peak force, maximum deformation and absorbed energy to fracture, respectively. Linear fractures were always seen in the frontal bone, with a similar pattern in three of the four skulls. These results can be used to develop bench-mark skull models to validate analytic models. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 194-9).

Background: Non-traumatic acute subdural haematomas enable study of the morbidity and mortality due to the haematoma without the effect of trauma. Whereas it is known that coagulation disorders worsen the outcome of spontaneous intracerebral haematomas, this has not been studied in non-traumatic acute subdural haematomas., Methods: In a series of 13 non-traumatic acute subdural haematomas admitted to our department between January 1995 and March 2002, we had 9 coagulopathy associated haematomas and 3 haematomas corresponding to the syndrome of 'spontaneous acute subdural haematoma of arterial origin'. Both groups were compared., Findings: Age and gender distribution were comparable. The bleeding source was a cortical artery in 2 of the 2 non-coagulopathy related haematomas operated on, but also in 2 of the 4 coagulopathy associated haematomas that underwent surgery. The average haematoma thickness was higher in the coagulopathy related haematomas. The mean Glasgow Coma Score on admission was 7.7 and the mortality rate was 55.6% in the coagulopathy related group. In the non-coagulopathy related haematomas the mean Glasgow Coma Score was 12.0 and the mortality rate 33.3%. The latter mortality rate corresponds well to that of a historical group of 'spontaneous acute subdural haematomas of arterial origin' collected from the literature., Interpretation: The outcome was worse in the non-traumatic acute subdural haematomas that were associated with a coagulation deficiency. While in all non-traumatic acute subdural haematomas the interval to surgery should be minimized, early recognition and urgent correction of coagulation deficiencies is certainly indicated.

Background: The technique of posterior fossa decompression, nowadays preferred by most neurosurgeons as the first surgical option in the treatment of hindbrain associated syringomyelia, was reintroduced in our center in 1989. We present a retrospective analysis of 22 patients with this pathology who underwent the procedure since then., Methods: In all patients diagnosis was made by MRI of the craniospinal junction. The operation consisted of a suboccipital craniectomy, removal of the posterior arc of C1, laminectomy of C2 or C3 when necessary and a wide duraplasty at the end. The intradural manipulations (opening of the arachnoid membrane, coagulation or resection of the tonsils) were not uniform. Postoperatively short- and long-term clinical outcome and MRI findings were assessed., Results: Sixteen out of 21 patients (76%) experienced an improvement in the early follow-up period. In the late follow-up period 13 out of 19 patients (68%) were improved, whereas five patients (26%) experienced a marked deterioration. There was no unequivocal effect on all symptoms and signs. Postoperative MR images showed a favorable result in 16 out of 20 patients (80%), consisting of syrinx collapse or reduction of the syrinx diameter., Conclusions: We conclude that decompression of the posterior fossa is a safe procedure with a considerable chance of clinical improvement. Although total syrinx collapse is not as frequently seen as in syrinx shunting procedures, the clinical outcome may be better. Moreover, there seemed to be no unequivocal correlation between clinical outcome and postoperative syrinx size in the present study.

Mesenteric venous thrombosis is an infrequent but distinct form of intestinal ischaemia. We report a case of acute mesenteric venous thrombosis diagnosed by computed tomography. Laparoscopy permitted to establish the extent of the ischaemia. Initially, high doses streptokinase were administered for 6 hours, followed by heparinotherapy for 10 hours, with the aim to reduce the length of bowel to be resected. One day later, intestinal resection was carried out, followed by postoperative anticoagulation.