If it was serialized, it'd likely be base64 encoded afterwards; why it was stored as a blob well, that's kind of dumb. Try print_r($result) to see what's in your array.
Or, you can always:
PHP Code:
foreach ($result as $arg=>$val) {
echo "$arg is $val<br>";
}
How do you know its base64? Is it terminating with a few =? If not, it may not be base64.