Having previously been treated for CD, and have received injections during the treatment plan I'm not sure of the 'long term' benefit. Spasms and cramps are spasms and cramps. There are different degree's whereas I literally had to pull my head over at times while at other times it only hurts. Revance explains their testing protocol below and I can't really say if it would help.
While the shots did help, they were only a band aid until a permanent solution could be found. That was accomplish by fusing C1 through C7.
*Median duration of effect was defined as time from treatment until loss of ≥80% of the peak effect (change from baseline in TWSTRS total score averaged across weeks four and six).