Abstract
It has been found in a group of 455 gynaecological patients that not all the voluntary muscles of the body respond to suxamethonium in the same way. One group of muscles (e.g. biceps) which is sensitive to suxamethonium, responds by fasciculating in almost every individual. A second, resistant, group of muscles (e.g. pectoralis major) is almost totally unresponsive to suxamethonium. A third muscle group (e.g. triceps) shows fasciculations in about 60% of cases and appears intimately associated with the development of suxamethonium pains, for if fasciculations do occur then suxamethonium pains are likely to ensue, but not necessarily involving all the fasciculating muscles. A theory to account for these different groups has been proposed involving the known variation in distribution of red and white muscle fibres throughout the body.