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.
Treatment OF Repetitive Stress Injury
Treatment of Repetitive Stress Injury should focus on conservative measures. The first step is to limit exposure to the particular repetitive activities that may have contributed to the development of the Repetitive Stress Injury and that continue to induce pain. Sick leave should be avoided because it may develop into chronic disability.
Unfortunately, there is little evidence of the effectiveness of any specific medical intervention for Repetitive Stress Injury. Clinical treatment is usually targeted at relief of pain and acute inflammation as well as restoration or range of motion. Inflammatory conditions are often treated with the PRICE regimen: protection (preventing further injury, perhaps by bracing), rest or activity modification , ice, compression, and elevation to minimize swelling.
Icing of the limb for about 20 minutes three times daily in conjunction with wrist or elbow splinting can decrease symptoms. Other modalities that may be helpful in controlling pain symptoms in the acute phase of treatment include ultrasound, iontophoresis, and transcutaneous electrical nerve stimulation. Manual massage, spray and stretch techniques may also alleviate pain in some patients.
Medications may also be used to control pain and inflammation. Nonsteroidal anti-inflammatory drugs (NSAIDs) are usually the first line pharmaceuticals for acute inflammation. Local anesthetic patches can be helpful if they are placed over a localized area of arm pain. Trigger point injections with local anesthetic or dry needling can also be considered to relieve myofascial pain. Oral narcotis should generally be avoided, given the risk of opioids dependency.
Restoration of sleep can be helpful in reducing pain perception as well as in decreasing the risk for development of depression.If signs of depression are present, appropriate antidepressant treatment or referral to psychiatrist or psychologist in indicated.
The rehabilitation of a patient with Repetitive Stress Injury is best achieved by a multidisciplinary approach with the physician overseeing the treatment plan and following the progress of the patient. A referral to skilled physical and occupational therapy is essential. The therapists may provide several modalities (mentioned before) to decrease pain and to facilitate an active stretching and strengthening program. They not only focus on the affected limb but also work on total body biomechanics and postural control at the workstation and at home.
Progressive resistive exercise programs can be used, but worsening of pain symptoms with increasing exertion is often an issue. Progressive resistive exercises can have more benefit if they are introduce with small increments in resistance, allowing the patient to slowly adjust. This approach can improve participation of the patient and thus increase strength gains with treatment.
Further physical conditioning with regimented aerobic training, catered to the patient’s personal interests, and institution of a home exercise program may reduce pain, improve stress management, and increase work capacity. It is important to encourage physical activity as much as possible. General aerobic conditioning can be effective in encouraging a positive health perception.
Relaxation training may also be helpful for chronic, nonspecific regional arm pain. Continued surveillance and treatment of mental health can be imperative in recovery.
Cognitive behavioral therapy techniques can be used to treat the maladaptive beliefs and misconceptions that may accompany upper extremity dysfunction. Moreover, weight reduction, if needed, and smoking cessation should also be included in any plan to improve overall health.
Other rehabilitative measures for Repetitive Stress Injury include the fabrication of splints and the introduction of adaptive equipment that may assist in functional activities at home and in the workplace.
Some therapists are specially trained to perform work site analysis and to suggest ergonomic modifications. Modifications can range from adjustment in chair height and computer mouse position to the substitution of large handled tools, depending on the occupation.