Fibrositic myofascial pain in intermittent claudication. Effect of anesthetic block of trigger points on exercise tolerance.

The blocking of trigger points in the calf by the local injection of an anesthetic agent was performed in 15 patients with intermittent claudication. Reactive and exercise hyperemia, work load and duration of exercise were recorded before and after infiltration of the trigger points. Reactive hyperemia does not change, but the exercise tolerance of the leg significantly improves after local blocking of the trigger areas and the exercise hyperemia increases because of the higher work load. The pain pattern of intermittent claudication can be activated by the summation of abnormal input from muscles, due to contraction in the presence of anoxia, with activity from trigger points. Local infiltration of trigger areas blocks theirir activity. The vicious cycle of pain is interrupted and the exercise tolerance of the leg is increased, without improving blood circulation.