Intra-cerebral haemorrhages may be primary (i.e. occurring at the time of the trauma) or secondary, due to the effects of raised intra-cranial pressure and cerebral oedema.
When an intra-cerebral haemorrhage has been caused by natural disease (such as systemic hypertension, for example), the haemorrhage is usually single, and located in the deep grey matter (e.g. thalamus), pons or cerebellum. A careful search for supporting evidence of hypertension should be made, such as left ventricular hypertrophy.
The phenomenon of delayed traumatic haemorrhage - identified in 1891 by Bollinger - is a relatively rare event. Case reports had identified haemorrhages predominantly occurring in the frontal and temporal lobes, but occasionally they were multiple, and located in the basal ganglia, parietal cortex and cerebellum.
The pathogenesis of such bleeds is incompletely understood, but may relate to localised intra-vascular coagulation following trauma, localised infarction and necrosis, subsequent fibrinolysis and gradual haemorrhage formation. Treatment of head injury, including the reduction of cerebral oedema and the use of diuretics may also contribute to their formation.