Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Pronator Syndrome


Differential Diagnosis

Specialists

  • Family Physician
  • Neurologist
  • Occupational Therapist
  • Orthopedic (Orthopaedic) Surgeon
  • Physiatrist (Physical Medicine and Rehabilitation Specialist)
  • Physical Therapist
  • Sports Medicine Physician

Comorbid Conditions

Factors Influencing Duration

Length of disability depends on the severity of nerve compression, whether the dominant or nondominant extremity is affected, whether surgery was required, and the individual’s job requirements. If pain medication is needed after return to work, company policy on medication use should be reviewed to determine if it is compatible with job safety and function.

Medical Codes

ICD-9-CM:
354.1 - Lesion of Median Nerve, Other; Median Nerve Neuritis

Overview

Pronator syndrome is a condition in which the median nerve becomes compressed in the forearm below (distal to) the elbow, causing pain, as well as tingling and numbness (paresthesia). Nerve compression may occur from direct forearm trauma, bony abnormalities, restrictive fibrous bands of scar tissue, or tumors. Repetitive or forceful twisting or gripping movements result in increased muscle bulk of the pronator teres muscle in the anterior forearm. This additional bulk may compress the median nerve passing between the two heads of the muscle. Pronator syndrome can mimic carpal tunnel syndrome and anterior interosseous nerve syndrome, and may be difficult to identify.

Incidence and Prevalence: Pronator syndrome is rare, but is the second most common cause of median nerve compression after carpal tunnel syndrome (Lee). Pronator syndrome is responsible for less than 1% of all median nerve entrapment disorders (Mercier).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Increased risk for pronator syndrome may be associated with individuals involved in repetitive elbow, wrist, and hand movements such as chopping wood, playing racquet sports, rowing, weight lifting, or throwing. However, pronator syndrome is four times more likely to affect women than men, suggesting that anatomic anomalies (structural variations) and not overuse is the dominant risk factor. The dominant arm is most likely to be affected, particularly if the individual is heavily muscled (muscular hypertrophy).

Pronator syndrome is most commonly diagnosed in individuals between the ages of 40 and 50 (Lee).

Source: Medical Disability Advisor



Diagnosis

History: The individual may report a diffuse, aching pain and a feeling of clumsiness and fatigue in the forearm after prolonged or repetitive activity. Pain may radiate down to the wrist or up the arm above the elbow. There may be instances of paresthesia in the thumb and index finger, and the individual may report loss of dexterity in the hand. Symptoms typically worsen with activity, especially forceful gripping or twisting movements; symptoms generally improve with rest. Unlike median nerve compression at the carpal tunnel, nighttime symptoms are rarely reported.

Physical exam: The individual's involved forearm may appear thicker (hypertrophied) than the uninvolved side. There may be tenderness on the flexor surface of the forearm in response to the examiner touching (palpating) the point where the median nerve enters the pronator teres muscle near the elbow. Like carpal tunnel syndrome, compression of the median nerve from pronator syndrome may result in pain or paresthesia at the thenar muscles of the thumb (Disabella).

Muscle testing may reveal weakness in the forearm and hand intrinsic muscles supplied by the median nerve (e.g., forearm pronators, wrist flexors, and finger flexors). Pinch strength may be diminished, and there may be weakness with resisted middle finger flexion. Resisted forearm pronation, during which the elbow is extended and the wrist flexed (pronator syndrome test), may reproduce painful symptoms. Resisting elbow flexion at 120 to 130 degrees while the forearm is facing downward (in a position of maximal supination) also may reproduce symptoms. Tapping of the median nerve at the elbow may elicit pain and tingling (Tinel sign); conversely, tapping of the median nerve at the wrist will not elicit symptoms. A complete neurological examination should be performed to rule out spinal sources of neuropathy. Physical exam findings alone are not diagnostic.

Tests: Laboratory blood tests (complete blood count [CBC], uric acid, erythrocyte sedimentation rate [ESR], and antinuclear antibody [ANA] testing) are typically not useful in establishing this diagnosis. Electromyography (EMG) and nerve conduction velocity (NCV) testing may be performed to confirm the diagnosis and rule out other causes of median nerve entrapment (e.g., carpal tunnel syndrome, cervical radiculopathy, thoracic outlet syndrome).

False positive nerve conduction test results are common for this condition. The traditional median nerve motor conduction test records the response from the abductor pollicis muscle in the palm. This muscle is affected by carpal tunnel syndrome. Median nerve motor conduction tests results showing slow conduction of the median nerve in the forearm and reduced amplitude of the motor response in the palm with median nerve stimulation at the elbow most commonly represent moderate or severe carpal tunnel syndrome with conduction block at the wrist of the fastest axons, and not pronator syndrome. Needle EMG evidence of denervation in forearm muscles innervated by the median nerve should be observed before pronator syndrome is diagnosed.

X-rays and magnetic resonance imaging (MRI) also may be performed to rule out bony or soft tissue causes of compression.

Source: Medical Disability Advisor



Treatment

Pronator syndrome cases associated with heavy arm use are initially treated with protection, rest, ice, compression, elevation, medication, and modalities (PRICEMM). During the acute phase of this condition, the individual should modify activities to avoid movements and forces that increase symptoms. The individual also may benefit from temporary use of a brace or splint to allow the limb to rest; severe cases may require activity modification and splinting for up to 6 months (Kim; Santiago). Nonsteroidal anti-inflammatory drugs (NSAIDs) may be tried during this phase, although in general, they do not affect nerve entrapment syndromes. In some cases, tricyclic antidepressants may be prescribed, particularly if sleep is disturbed. Anticonvulsant medications may be indicated for neuropathic pain. Physical therapy may be helpful to loosen tight musculature and restore strength to the affected limb.

Local injection of an anesthetic agent (median nerve block) or corticosteroids about the median nerve at the elbow may be necessary to provide symptom relief. Rarely, surgery may be needed to release the tight structures about the median nerve (anatomic anomalies).

Source: Medical Disability Advisor



Prognosis

The outcome of pronator syndrome is excellent as long as the individual eliminates the cause of the original injury. Approximately 50% of individuals with pronator syndrome receiving conservative treatment experience resolution of symptoms within 4 months (Lee). Up to 90% of those who undergo median nerve decompression surgery report good to excellent results (Lee).

Source: Medical Disability Advisor



Rehabilitation

The focus of rehabilitation for pronator syndrome is to restore full use of the elbow, wrist, and hand with a painless forearm. The first goal of therapy is to identify the sources of strain and to modify activities to avoid repetitive movements and overuse of the affected extremity. Individuals are advised to avoid forceful gripping or repeated pronation and supination activities. Ice may be used to reduce pain, and the individual may be instructed to perform ice massage on the affected forearm. The therapist may instruct the individual to protect the affected extremity by using an immobilization splint. Other modalities, including ultrasound, electrical stimulation, phonophoresis, and iontophoresis, may be useful to decrease pain, control swelling, and facilitate stretching exercises of tight forearm musculature (Santiago).

After the acute phase, stretching of tight forearm muscles (e.g., pronator teres, forearm flexors) may be facilitated by the application of heat before stretching. Soft tissue mobilization of tight structures may also be helpful. Once painful symptoms are reduced, strengthening exercises may be initiated for the hand, wrist, and elbow, at first isometrically and then against gentle resistance within pain-free ranges of motion, progressing as indicated. It is important to protect against further injury during this time, especially through either too little or too much activity. As strength returns, the individual may begin conditioning exercises with progression to full activity. An ergonomic assessment of the individual’s workplace may be needed to evaluate proper biomechanics with task performance to help reduce the risk of re-injury.

A home program should be taught to complement supervised rehabilitation, and should be continued after the completion of physical therapy.

Source: Medical Disability Advisor



Complications

Unresolved pronator syndrome may result in chronic weakness, pain, and impaired functional use of the hand and wrist. Permanent median nerve damage may result.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

The extent of injury, associated motor and sensory deficits, and type of work will dictate the type of work restrictions or accommodations necessary. Individuals may need to temporarily immobilize the affected extremity to allow healing to fully occur.

Source: Medical Disability Advisor



Regarding diagnosis

Regarding diagnosis:
  • Does individual have a history of repetitive task-type injury to the upper extremity in which repeated or forceful gripping or twisting occurs?
  • Did individual have complaints of diffuse, aching pain and a feeling of clumsiness and fatigue in the forearm with activity?
  • Were there instances of paresthesia in the thumb and index finger? Loss of hand dexterity?
  • Did individual’s symptoms typically worsen with activity, especially forceful gripping or twisting movements, and improve with rest?
  • Was there an absence of nighttime symptoms?
  • Do individual’s forearm flexor muscles appear thickened (hypertrophied)?
  • Did individual experience tenderness at the flexor surface of the forearm in response to the examiner touching (palpating) the muscles near the elbow?
  • Did individual exhibit weakness in the forearm and hand intrinsic muscles supplied by the median nerve (e.g., forearm pronators, wrist flexors, and finger flexors)?
  • Did resisted forearm pronation (pronator syndrome test) reproduce symptoms?
  • Did tapping of the median nerve at the elbow elicit pain and tingling (Tinel sign)?
  • Was EMG and NCV testing used properly to confirm the diagnosis?
  • Were x-rays needed? MRI?
  • Did workup include a complete neurological examination?

Regarding treatment:

  • Was diagnosis of pronator syndrome confirmed by needle EMG?
  • Was individual treated with protection, rest, ice, compression, elevation, medication, and modalities (PRICEMM)? Was this helpful?
  • Is individual modifying activities to avoid movements and forces that bring on symptoms?
  • Is individual using temporary brace or splint to allow the injured limb to rest?
  • Are NSAIDs indicated? Are tricyclic antidepressants or anticonvulsant medications necessary?
  • Is individual receiving physical therapy? Is individual compliant in performing home exercise program as instructed?
  • Was individual’s work environment assessed to facilitate proper biomechanics with task performance? Is ergonomic setup correct?
  • Has individual received median nerve block or injection of corticosteroids into the median nerve? Did this resolve symptoms?
  • Is surgery necessary to release the tight structures from about the median nerve (median nerve decompression surgery)?

Regarding prognosis:

  • Were modifications made to the individual’s job requirements during recovery?
  • Was the dominant or nondominant arm affected?
  • Has physical therapy been completed as recommended? Would additional therapy benefit individual?
  • Did adequate time elapse for full recovery?
  • Was individual able to eliminate the cause of the original injury?
  • Did permanent median nerve damage result?

Source: Medical Disability Advisor



References

Cited

Disabella, Vincent N. "Elbow and Forearm Overuse Injuries." eMedicine. Eds. Joseph P. Garry, et al. 12 Feb. 2008. Medscape. 11 Dec. 2009 <http://emedicine.medscape.com/article/96638-overview>.

Kim, Richard Y., Valerie M. Wolfe, and Melvin Rosenwasser. "Section I – Entrapment Neuropathies Around the Elbow." DeLee and Drez’s Orthopaedic Sports Medicine. Eds. Jesse C. DeLee, David Drez, and Mark D. Miller. 3rd ed. Saunders Elsevier, 2009. MD Consult. Elsevier, Inc. <http://www.mdconsult.com/das/book/body/174984473-6/0/2079/37.html?tocnode=57567697&fromURL=37.html#4-u1.0-B978-1-4160-3143-7.00019-1--sc11_2755>.

Lee, Michael J., and Paul C. LaStayo. "Compressions That Mimic Carpal Tunnel Syndrome." Journal of Orthopadedic Sports Physical Therapy 34 1 (2004): 601-609. PubMed. 11 Dec. 2009 <PMID: 15552706>.

Mercier, Lonnie R. "Pronator Syndrome." Ferri's Clinical Advisor 2010. Ed. Fred Ferri. Mosby Elsevier, 2010. MD Consult. Elsevier, Inc. 10 Dec. 2009 <http://www.mdconsult.com/das/book/body/174984473-4/928098314/2088/531.html#4-u1.0-B978-0-323-05609-0.00025-3--sc0295_10938>.

Santiago, Francisco H., and Ramon Vallarino. "Chapter 20: Median Neuropathy." Essentials of Physical Medicine and Rehabilitation. Eds. Walter R. Frontera, Julie K. Silver, and Thomas Rizzo. 2nd ed. Philadelphia: Saunders, Elsevier, 2008. MD Consult. Elsevier, Inc. 10 Dec. 2009 <http://www.mdconsult.com/das/book/body/174984473-6/928098314/1678/23.html#4-u1.0-B978-1-4160-4007-1.50022-5--cesec5_314>.

General

Chumbley, Eric M., Frrancis G. O'Connor, and Robert P. Nirschi. "Evaluation of Overuse Elbow Injuries." American Family Physician. Feb. 2000. American Academy of Family Physicians (AAFP). 10 Dec. 2009 <http://www.aafp.org/afp/20000201/691.html>.

Tsai, Peter, and David Steinberg. "Median and Radial Nerve Compression About the Elbow." Journal of Bone and Joint Surgery 90 (2008): 420-428.

Waldman, Steven D., ed. "Chapter 66: Entrapment Neuropathies of the Elbow and Forearm." Pain Management. 1st ed. Saunders Elsevier, 2006. MD Consult. Elsevier, Inc. 10 Dec. 2009 <http://www.mdconsult.com/book/player/book.do?method=display&type=bookPage&decorator=header&eid=4-u1.0-B978-0-7216-0334-6.50070-4--cesec7&uniq=174984473&isbn=978-0-7216-0334-6&sid=928098314>.

Source: Medical Disability Advisor






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