Botulinum Toxin A for the Treatment of Chronic Lumbar Back Pain

One hundred sixty subjects will be randomly assigned to one of four arms (placebo/placebo, placebo/Botox, Botox/placebo, Botox/Botox). In the first of two phases, randomized subjects will blindly receive either Botox® (study arms Botox/placebo and Botox/Botox) or placebo (study arms placebo/placebo and placebo/Botox) injection into the lumbar paraspinal muscles. The subjects will be assessed using validated scales for pain and disability prior to injection and monthly thereafter for four months. In the second phase, a second set of lumbar injections will be administered based on the initial randomization and will blindly receive either Botox® (study arms placebo/Botox and Botox/Botox) or placebo (study arms placebo/placebo and Botox/placebo) injection into the lumbar paraspinal muscles. The subjects will again be assessed using the same validated scales for pain and disability, prior to injection and monthly thereafter, but for six months to extend the monitoring period to better define the limits of duration of effect. This will result in half of the subjects being crossed-over from Botox® to placebo (study arm Botox/placebo) or vice versa (study arm placebo/Botox) and one quarter of subjects receiving two courses of either Botox® alone (Botox/Botox) or placebo alone (placebo/placebo). All subjects will continue to receive medication and/or physiotherapy per standard of care but those treatments will be recorded and controlled for in the data analysis.