Craig N. Kloeden

Extradural haematoma: Trends in outcome over 35 years

We have reviewed 35 years experience of extradural haemorrhage (EDH) in a large neurosurgical unit, based in two university hospitals, one dealing exclusively with children and the other a general hospital. A steady reduction in the mortality rate from 29 to 8.5% occurred during that period. A trend towards earlier diagnosis is noted and an increasing proportion of rural patients has been evident throughout the study period. During the time-period studied there were many significant developments: the establishment of a modern neurosurgical unit, the evolution of an intensive care unit, the availability of CT head scanning and the formal organization of rapid retrieval to service country areas. However, no single feature could be identified as the major contributor to falling mortality results. Clinical awareness and early diagnosis are the keys to successful management of EDH.

Countermeasures to the problem of accidents to intoxicated pedestrians

A substantial part of the pedestrian accident problem arises from intoxicated pedestrians. Possible countermeasures are reviewed, organised into: (a) prevention of high levels of intoxication in pedestrians, (b) minimising pedestrian activity in the intoxicated, and (c) minimising risk of injury among intoxicated pedestrians. It is concluded that improved safety of intoxicated pedestrians is most likely to come about by making the environment safer for all pedestrians, drunk or sober. The measure that would be expected to have the greatest effect quickest is a reduced speed limit, especially in locations where traffic is busy and there are many pedestrians.

A method of estimating linear and angular accelerations in head impacts to pedestrians

In order to investigate the relationship between impact to the head and brain injury, we have developed a method, using information obtained from reconstruction of the collisions, of estimating the peak linear and angular accelerations of the head for pedestrian impacts on a vehicle. This information includes the location of the impact on the head, the impact velocity of the head, and the stiffness of the struck surface. In developing the method we assumed that the velocity of the head on striking the vehicle was the same as the velocity of the vehicle itself, that the force vector was normal to the surface of the skull, that the force-deflection curve characterising the combined response of the impacted surfaces was linear, and that the kinetic energy of the head immediately prior to impact was converted into strain energy in deforming the head and the vehicle structure. Only the loading phase of the impact was considered, there was no assumption of an elastic unloading phase. Using cadavers, the validity of these assumptions and hence the usefulness of the method were tested by comparing the estimates of peak linear acceleration with the results of 18 pedestrian-vehicle impact reconstructions. On average, the method underestimated the experimental values by about 15%, with a range of +/- 35%. The results from the application of this method are currently being used to study the relationship between the magnitude and direction of the impact to the head and the distribution and severity of the brain injury resulting from actual collisions.

Do Full-Face Helmets Offer Greater Protection Against Cervical Spinal Cord Injury than Open-Face Helmets?

In 1979, Yeo (1979a,b) reported a lower likelihood of damage to the cord of the cervical spine (cervical spinal cord injury, or cervical SCI) for wearers of full-face helmets compared with open-face helmets among motorcyclists that had sustained a head impact. However, it appears that the study suffered from factors biasing the results away from the null hypothesis. The present study suggests that there may be no added benefit or harm of the full-face helmet relative to the open-face helmet on cervical SCI.

Safe speed limits for a safe system: The relationship between speed limit and fatal crash rate for different crash types

ABSTRACT Objective: The objective of this article is to provide empirical evidence for safe speed limits that will meet the objectives of the Safe System by examining the relationship between speed limit and injury severity for different crash types, using police-reported crash data. Method: Police-reported crashes from 2 Australian jurisdictions were used to calculate a fatal crash rate by speed limit and crash type. Example safe speed limits were defined using threshold risk levels. Results: A positive exponential relationship between speed limit and fatality rate was found. For an example fatality rate threshold of 1 in 100 crashes it was found that safe speed limits are 40 km/h for pedestrian crashes; 50 km/h for head-on crashes; 60 km/h for hit fixed object crashes; 80 km/h for right angle, right turn, and left road/rollover crashes; and 110 km/h or more for rear-end crashes. Conclusions: The positive exponential relationship between speed limit and fatal crash rate is consistent with prior research into speed and crash risk. The results indicate that speed zones of 100 km/h or more only meet the objectives of the Safe System, with regard to fatal crashes, where all crash types except rear-end crashes are exceedingly rare, such as on a high standard restricted access highway with a safe roadside design.