Carpal Tunnel Release: Brown Two Portal Technique

Abstract

Carpal tunnel syndrome was first used in the 1930s to describe entrapment neuropathy of the median nerve at the wrist. The carpal tunnel is bounded on three sides by the carpal bones and on the volar side by the transverse carpal ligament. The transverse carpal ligament begins at the distal wrist crease that is a transition zone between the volar forearm fascia and transverse carpal ligament. The transverse carpal ligament continues from the distal wrist crease distalward to a point inthe palm 3–3.5 cm distal to the distal wrist crease. The transverse carpal ligament has an air foile configuration, thick in the middle and tapering on each end. Through the carpal tunnel pass, nine flexor tendons, the median nerve, and the flexor tenosynovium investing the tendons. The carpal tunnel is a defined space and cannot enlarge. The median nerve itself does not typically enlarge nor do the tendons and therefore the third structure, the flexor tenosynovium, is the structure that becomes enlarged and results in increased pressure on the median nerve. The flexor tenosynovium may become enlarged for a variety of reasons. Although repetitive type work activities can result in tenosynovial proliferation and carpal tunnel syndrome, it is not a prerequisite to be involved in this type of activity to develop carpal tunnel syndrome. In fact, a great many patients present wondering why they have carpal tunnel syndrome when are not computer operators, assembly line workers, cake decorators, or meat packers or processors, etc. Probably the second most common cause of carpal tunnel syndrome following repetitive type work activities is the gradual and continual weight gain of a pound per year to which most Americans are prone, thereby resulting in a fairly overweight, middle-aged male or female. And indeed the highest incidence of carpal tunnel syndrome onset is 35–45 years of age. Cyclic fluctuations of edema can also leave residual fibrotic tissue in the tenosynvium.