Repetitive Stress Injury is also known as, repetitive strain injury, work related upper limb disorder (WRULD), and occupational overuse syndrome. Specific disorders that may fall under the classification of repeated stress injury include adhesive capsulitis, bursitis, carpal tunnel syndrome, cervical spondylosis, writer’s cramp, cubital tunnel syndrome (ulnar nerve entrapment), epicondylitis, ganglion cyst, peritendonitis, rotator cuff syndrome, tendonitis, trigger finger or thumb, and thoracic outlet syndrome.
Nonspecific disorders may affect muscles, tendons, bursae, or joints of the neck, shoulders, upper back, elbows, wrists, or hands. “Diffuse Repetitive Stress Injury” refers to a nonspecific pain syndrome in which pain is present in several areas, attributed to underlying nerve damage as a result of repetitive motions. Occupations commonly associated with Repetitive Stress Injury disorders include working for long periods of time without rest breaks at a computer, desk, or assembly line.
Causes of repetitive stress injury
Repetitive motion and prolonged tension in muscles that are held in a continuous position are believed to cause micro trauma to underlying tissues, which injures muscles, tendon sheaths, ligaments, nerve sheaths, or other structures, resulting in swelling and pain.
Swelling of muscles or tendon sheaths is believed to reduce blood flow to the affected tissues and the surrounding area, exacerbating the symptoms. Repetitive motions aggravate the underlying micro trauma to tissues and prevent healing.
Risk Factors of repetitive stress injury
Risk factors include an ergonomically unsound work station, poor posture, and excessive workload. Working for long periods without rest and using repetitive movements or repetitive forceful hand motions (twisting or gripping) are also contributing factors, as are prolonged body vibration ( such as from power tools), fatigue, cold work environments, and psychosocial stressors.
Symptoms of repetitive stress injury
Symptoms may accumulate over long periods of time and include recurring sharp or dull pain, soreness, stiffness, tingling and numbness, loss of sensation, limited range of motion, weakness, fatigue, or persistent tension in the neck, shoulders, upper back, elbows, wrists, or hands.
Pain may be referred from one area to another, such as when nerve impingement in the neck or shoulder cause pain in the forearm or hand. Less commonly, pain may also be referred to the back or lower extremities.
Symptoms in the arms or hands may worsen when lying in bed. Routine daily activities such as driving, carrying groceries, housework, or gardening may worsen symptoms. Without treatment, symptoms may becomes continuous and progress to long term injury and disability.
(Victoria J. Fraser, M. d.; Disease and Disorders; 2007; 711-712)
Physical Examination for Repetitive Stress Injury
Repetitive Stress Injury is a diagnosis of exclusion. Typically, there are no objective physical findings. Hence, the physical examination should be comprehensive and focus on ruling out alternative diagnoses. It should include a thorough musculoskeletal examination with inspection, palpation, and testing of passive and active range of motion of the cervical spine, shoulder, elbow, wrist, and fingers.
There is typically no evidence of muscle atrophy or other deformity. There may be pain on active and passive range of motion, but there is generally no restriction of motion when the examiner takes the joint through a full arc. There may be diffuse myofascial pain with palpation over the symptomatic region. In addition, there may be evidence of one or more focal fibro-myalgia tender points on the symptomatic as well as on the asymptomatic arm.
Neurologic assessment can rule out localized nerve disease by investigating for dermatomal, myotomal, or peripheral nerve abnormalities. In Repetitive Stress Injury, deep tendon reflexes are normal and symmetric. Manual muscle strength testing should be performed but is generally inconsistent, depending on the patient’s effort and pain level with exertion. Objective and reproducible strength tests can be performed with a hand or pinch dynamometer if level of strength is uncertain with examiner resistance.
Provocative test that reproduce specific pain patterns can help rule out alternative diagnoses.
Diagnostic tests are ordered if the diagnosis is not clear after the history and physical examination, if the results of the testing will change management, or if the testing is needed for medico legal reasons.
The tests are used to exclude other definitive conditions that may remain in the differential diagnosis after examination. Needle electromyography and nerve conductions studies are often necessary to rule out a peripheral nerve lesion, such as median nerve entrapment at the wrist. Electro-diagnostic studies provide the distinct advantage of offering objective data by quantifying the degree of nerve impairment in a manner that is independent of the patient’s pain behaviors. This can be very important when injured workers have interest in substantial secondary gain and may not be reliable in their effort or honesty when motor and sensory nerve function is tested on physical examination.
Imaging is likely to be normal in Repetitive Stress Injury. Plain radiographs of the suspected site of disease will generally not reveal a fracture, the absence of blunt trauma but may reveal underlying degenerative changes that may or may not account for the patient’s symptoms.
Magnetic resonance imaging of the cervical spine and shoulder is often ordered to rule out disc herniation, neuroforaminal stenosis, and rotator cuff disease. This study may be useful only if there is concern for one of these diagnoses based on physical examination. Magnetic resonance imaging is expensive, and abnormalities such as disc bulging and degenerative spondylosis are often found in asymptomatic individuals and may not explain the current symptom complex.
Laboratory work is seldom necessary at the time of initial evaluation unless an underlying systemic illness is suspected.