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.   Hand, shoulder, and arm pain, with varied and additional symptoms described later in the “Symptoms” section, is of nerve origin and has been described in the medical literature for well over one hundred years. Until the post-WWII era, the cause was thought to be due entirely to anatomical abnormalities or direct trauma to the nerves lying above the collarbone. This is intuitively more understandable and another cause for continued controversy, since currently, in the majority of cases, there is a lack of an obvious and dramatic compressive factor in the majority of people afflicted with this disorder. Since WWII, however, there has been a slow recognition that repetitive work activities are increasingly responsible for the dramatic rise in the incidence of this disorder. TOS used to be considered extremely rare; however, in the current work environment, it is found to be increasingly common. Because of the lack of classical findings (blood-vessel disorders, progressive weakness, and electromyographic abnormality), it is usually termed “neurogenic TOS.”   .