Non-specific arm pain

Non-specific arm pain (NSAP) is a common chronic upper limb pain disorder that has previously been referred to as repetitive strain injury. NSAP is frequently associated with tasks that involve repetitive upper limb activities, such as intense computer use and light production work. What differentiates NSAP from other specific upper limb conditions is the lack of obvious tissue injury on clinical testing. It is only recently that the complex mechanisms underlying NSAP are beginning to be revealed. Although psychosocial stressors contribute to symptoms, the underlying pathophysiology appears to be one of subtle neuro-musculoskeletal injury that involves inflammation and tissue ischemia. Such features are likely to be a consequence of frequent low force, highly repetitive muscle activity that is carried out in constrained and sustained working postures. Patients consistently show features of a minor neuropathy, with clear signs of nerve trunk mechanical sensitivity and changes in peripheral nerve function. The consequences of such a minor nerve injury have been underestimated. It is now apparent that peripheral nerve inflammation in the absence of axonal degeneration is sufficient to drive abnormal nociceptive activity (e.g. axonal mechanical sensitivity). These changes would contribute to symptoms and also lead to chronicity. Simple analgesics and non-steroidal medication are usually ineffective in treating NSAP. However, where there are signs of peripheral nervous system involvement, neuropathic pain medications should be considered. Preventing the onset of NSAP will involve attention to the work environment and how the individual interacts within that environment, for example by reducing psychological and ergonomic stressors.