tokens: We then compare the prevalence of ET ( 400 - 900 cases per 100,000 ) to that of the other cerebellar degenerations ( ranging from < 0.5 - 9 cases per 100,000 , and in composite likely to be on the order of 20 cases per 100,000 ) and conclude that ET is 20 to 45 times more prevalent than all other forms of cerebellar degeneration combined .