A MULTIPLICATIVE STATISTICAL-MODEL PREDICTS THE SIZE DISTRIBUTION OF UNRUPTURED INTRACRANIAL ANEURYSMS

A statistical model for characterizing the erratic nature of aneurysm evolution is developed and tested. This model is based upon a multipli cative hypothesis, whereby it is theorized that the progressive change s in the size of a given aneurysm are determined by random multipliers . Such a model would predict that within a large population of aneurys ms, a lognormal histogram for aneurysm sizes would occur (i.e. the log arithms of aneurysm size would have a normal distribution). When appli ed to previously published clinical data of unruptured aneurysms by Cr ompton (1966) and McCormick et al. (1970), the model is found to adequ ately describe both sets of data. The methods introduced in this paper illustrate the utility of incorporating statistical and clinical insi ghts with fundamental biometry for studying the complex phenomena of a neurysm growth and rupture.