New advances in the mechanisms and etiology of carpal tunnel syndrome.

In recent years, knowledge about the etiological mechanisms of carpal tunnel syndrome (CTS) has evolved significantly, allowing for a better understanding of this pain syndrome. Some studies have demonstrated that patients with CTS exhibit sensory symptoms not only within the areas innervated by the median nerve but also in extra-median regions, i.e., forearm or shoulder. It has also been demonstrated that patients with CTS may exhibit widespread pressure hypersensitivity and generalized thermal hyperalgesia, but not hypoesthesia, which is not related to electro-diagnostic findings. In addition, fine motor control and pinch grip force disturbances have been found to be commonly observed in this patient population. All these data suggest that central sensitization mechanisms are involved in the somato-sensory and motor disturbances found in CTS, probably related to cortical plastic changes. The presence of sensitization mechanisms could play an important role in the development of bilateral sensory symptoms in CTS and also can determine the therapeutic strategies for this condition. We propose that therapeutic interventions applied to individuals with CTS should include approaches that would modulate nociceptive barrage into the central nervous system.