i have a block every 2 weeks (switching off between sgb and sympathetic) i have never had a spread problem. i have learned there is 1 very important factor when having them done...make sure the doc knowns what they are doing. i had a nurse practitioner once do a nerve block and had an awful result...my lower body ended up completely involved. the reality seems to be that in any person even with the best doc the possibility for a problem exists. as for the results following a single block, if you experience even limited positive results the procedure probably needs to be repeated. as someone else said when i first started having them done and in general my doc does 1 then another 7 days later if the improvement lasts longer than she maintains the 7 day cycle for about a month just to get a base line. if however the second in the series is less effective she tries to get patients in in 5-6 days the following time and sees if that works better. also to be considered is the injection that is being done. the ladocaine wears of more quickly...there is a blend injection (sorry dont know the name but i can find out if you would like) that works better...at least for me.
lauren