Eighteen trials (n=1,362) were included: 9 double-blind RCTs (n=640), 2 single-blind RCTs (n=101) and 7 open trials (n=621).
All 5 placebo-controlled double-blind trials showed a statistically significant clinical benefit with a single injection of SCS, lasting from within the first day to approximately 4 weeks.
A superior effect was found with i.m. SCS compared with nasal steroids in one of 2 trials comparing these treatments.
One trial found i.m. SCS to be of equal good benefit to oral steroids in relieving symptoms for more than 3 weeks.
Six of the 7 open trials showed benefits of i.m. SCS.
None of the trials reported statistically significant differences between the SCS formulations with respect to efficacy, onset and duration.
There was no statistically significant difference in side-effects reported in the double-blind placebo-controlled trials. Minor clinical side-effects were reported in the comparative studies, with similar effects observed across different SCS formulae.
The trials that reported physiological side-effects found only a few for i.m. SCS.
All trials were published pre-1988.