Differences in the intracranial pressure caused by a 'blow' and/or a 'fall'--an experimental study using physical models of the head and neck.

In cases of a severe head injury caused by a fall, coup contusions are either absent or very minor, in contrast to presence of extensive contre-coup damage. In cases of a severe blow to head, however, the reverse occurs, with contre-coup lesions a rarity and coup damage extensive. To investigate this further, head injuries caused by a 'blow' or a 'fall' have been studied, using physical human models of the head and neck, both filled with distilled, degassed water and fixed onto a dummy torso. An impact of a constant magnitude was applied to the midoccipital region in 'blow' and 'fall' experiments, and the acceleration of the head and changes in the intracranial pressure were measured, with the resulting data analyzed by a computer. In both experiments, the peak amplitude of the acceleration pulse were almost the same. Similarly, the intracranial pressure curve at the impact site consisted of a positive pulse that hardly differed, nor did the peak amplitude of that pulse vary significantly. In the 'blow' experiment, however, the intracranial pressure curve at the site opposite the impact consisted of a negative pulse, whereas in the 'fall' experiment, the intracranial pressure recorded at the same area was negative but of a longer duration, with an absolute value that was slightly greater. Our results indicate that an impact to the head triggers a different response in the intracranial space, dependent on whether that impact force was caused by a 'blow' or a 'fall'.