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.

Nerve Injury


Related Terms

  • Nerve Transection
  • Nerve Trauma

Differential Diagnosis

Specialists

  • Neurologist
  • Neurosurgeon
  • Occupational Therapist
  • Physiatrist (Physical Medicine and Rehabilitation Specialist)
  • Physical Therapist

Comorbid Conditions

Factors Influencing Duration

Duration depends on the site and severity of the nerve injury. The severity of associated injuries to bones, blood vessels, muscles, and tendons may influence functional outcome and contribute to disability. Disability depends on specific job duties and specific nerves injured; it is not only related to grade of nerve injury but also to specific loss of function related to job requirements. Elderly individuals have poorer outcomes with surgical nerve repair.

Medical Codes

ICD-9-CM:
951 - Injury to Other Cranial Nerve(s)
951.0 - Injury to Oculomotor Nerve; Third Cranial Nerve
951.1 - Injury to Trochlear Nerve; Fourth Cranial Nerve
951.2 - Injury to Trigeminal Nerve; Fifth Cranial Nerve
951.3 - Injury to Abducens Nerve; Sixth Cranial Nerve
951.4 - Injury to Facial Nerve; Seventh Cranial Nerve
951.5 - Injury to Acoustic Nerve; Auditory Nerve; Eighth Cranial Nerve
951.6 - Injury to Accessory Nerve; Eleventh Cranial Nerve
951.7 - Injury to Hypoglossal Nerve; Twelfth Cranial Nerve
951.8 - Injury to Other Specified Cranial Nerves; Glossopharyngeal [9th Cranial] Nerve; Olfactory [1st Cranial] Nerve; Pneumogastric [10th Cranial] Nerve; Vagus [10th Cranial] Nerve
951.9 - Injury to Unspecified Cranial Nerve
953 - Injury to Nerve Roots and Spinal Plexus
953.0 - Injury to Nerve Roots and Spinal Plexus; Cervical Root
953.1 - Injury to Nerve Roots and Spinal Plexus; Dorsal Root
953.2 - Injury to Nerve Roots and Spinal Plexus; Lumbar Root
953.3 - Injury to Nerve Roots and Spinal Plexus; Sacral Root
953.4 - Injury to Nerve Roots and Spinal Plexus; Brachial Plexus Injury
953.5 - Injury to Nerve Roots and Spinal Plexus; Lumbosacral Plexus
953.8 - Injury to Nerve Roots and Spinal Plexus; Multiple Sites
953.9 - Injury to Nerve Roots and Spinal Plexus; Unspecified Site
954 - Injury to Other Nerve(s) of Trunk, Excluding Shoulder and Pelvic Girdles
954.0 - Injury to Other Nerve(s) of Trunk, Excluding Shoulder and Pelvic Girdles; Cervical Sympathetic
954.1 - Injury to Other Nerve(s) of Trunk, Excluding Shoulder and Pelvic Girdles; Other Sympathetic; Celiac Ganglion or Plexus; Inferior Mesenteric Plexus; Splanchnic Nerve(s); Stellate Ganglion
954.8 - Injury to Other Nerve(s) of Trunk, Excluding Shoulder and Pelvic Girdles; Other Specified Nerve(s) of Trunk
954.9 - Injury to Other Nerve(s) of Trunk, Excluding Shoulder and Pelvic Girdles; Unspecified Nerve of Trunk
955 - Injury to Peripheral Nerve(s) of Shoulder Girdle and Upper Limb
955.0 - Injury to Axillary Nerve
955.1 - Injury to Median Nerve
955.2 - Injury to Ulnar Nerve
955.3 - Injury to Radial Nerve
955.4 - Injury to Musculocutaneous Nerve
955.5 - Injury to Cutaneous Sensory Nerve, Upper Limb
955.6 - Injury to Digital Nerve
955.7 - Other Specified Nerve(s) of Shoulder Girdle and Upper Limb
955.8 - Multiple Nerves of Shoulder Girdle and Upper Limb
955.9 - Unspecified Nerve of Shoulder Girdle and Upper Limb
956 - Injury to Peripheral Nerve(s) of Pelvic Girdle and Lower Limb
956.0 - Injury to Sciatic Nerve
956.1 - Injury to Femoral Nerve
956.2 - Injury to Posterior Tibial Nerve
956.3 - Injury to Peroneal Nerve
956.4 - Injury to Peripheral Nerve(s) of Pelvic Girdle and Lower Limb; Cutaneous Sensory Nerve, Lower Limb
956.5 - Other Specified Nerve(s) of Pelvic Girdle and Lower Limb
956.8 - Injury to Peripheral Nerve(s) of Pelvic Girdle and Lower Limb; Multiple Nerves of Pelvic Girdle and Lower Limb
956.9 - Injury to Peripheral Nerve(s) of Pelvic Girdle and Lower Limb; Unspecified Nerve of Pelvic Girdle and Lower Limb
957 - Injury to Other and Unspecified Nerves
957.0 - Injury to Superficial Nerves of Head and Neck
957.1 - Injury to Other Specified Nerve(s)
957.8 - Injury to Multiple Nerves in Several Parts
957.9 - Nerve Injury, Unspecified; Nerve Injury NOS

Overview

Nerve injury includes total or partial transection of the nerve from stretching, cutting (laceration), compression, shearing, or crushing injuries.

Nerve injury may complicate injury from accidents, altercations, or other acute trauma, or it may develop more slowly from gradual compression caused by repetitive movements, as in carpal tunnel syndrome, or by sustained positions, as in radial nerve palsy. It may occur during or after surgery from traction or casting putting pressure on a nerve or because of incidental injury to a nerve located in the operative field.

Nerve injuries are classified by the degree of pathological change in the nerve. There are three main grades (Burnett, Hyde). The mildest injury is classified as grade I, and the most severe as grade III. Grade I nerve injury is called neurapraxia and is a minor injury from which full recovery occurs. With neurapraxia, there is no loss of nerve continuity, and functional loss is temporary. Grade II nerve injury, called axonotmesis, is a more severe injury, and although some secondary reparative processes occur, recovery can eventually take place. With axonotmesis, there is interruption of the internal nerve fibers (axons), but the external structures covering the nerve remain intact. A situation in which the nerve is severely damaged by crushing, laceration, or complete transection is called neurotmesis. This is a grade III injury, and it results in some degree of permanent impairment. With neurotmesis, there is complete functional loss unless surgery to re-attach the nerve is performed.

If a motor nerve is injured, the muscle(s) that the nerve supplies (innervate) loses function. If a sensory nerve is injured, the area innervated by the nerve loses sensation. The closer the nerve is to its origin in the spinal cord, the lower the chance of recovery. Nerve injury also may affect autonomic nerves, which control temperature regulation, blood pressure, heart rate, and digestion.

Incidence and Prevalence: Because nerves usually are injured along with other structures, there are no good incidence figures for nerve injuries themselves. However, it is estimated that 95% of nerve injuries that occur with a fracture are located in the upper extremity (Sharon). Nerve injuries occur with 48% of shoulder dislocations, 18% of knee dislocations, and 13% of hip dislocations (Sharon).

Source: Medical Disability Advisor



Causation and Known Risk Factors

There are no gender, racial, or ethnic predilections for nerve injuries. Certain occupations may predispose individuals to nerve injuries, as can some sports activities.

Source: Medical Disability Advisor



Diagnosis

History: The individual may complain of pain, tingling sensations (paresthesias), reduced sensation (hypoesthesia), or weakness of an extremity after trauma. Sometimes, no specific trauma is revealed.

Physical exam: General physical examination may reveal associated injuries. A standard neurologic exam may show some of the degree of nerve involvement, with confirmation of the complaints noted above. Peripheral nerve testing should include tests of light touch, pain, temperature, and vibration sensation. Other sensory tests include the ability to distinguish two pinpricks applied closely together (two-point discrimination) and the ability to appreciate small movements of the joint (joint position sense, proprioception). Motor testing includes tests of strength of muscles supplied by the affected nerve. In nerve injuries related to entrapment or compression, lightly tapping over the nerve where it is compressed may cause a painful or tingling, electric shock-like sensation (Tinel's sign). Reflexes typically are depressed or absent in the muscle groups supplied by the affected nerve. Ambulation and balance should be assessed in individuals with lower extremity nerve injuries.

Tests: Electromyography (EMG) helps to differentiate between grade I and higher grades of injury. A nerve conduction study, done by stimulating the nerve using an electrical stimulus on the skin and measuring the nerve response, indicates which motor and sensory nerves are affected. These tests begin to become abnormal within 10 to 21 days after the injury (Hyde, Sharon). A single test cannot distinguish between injuries that will demonstrate eventual recovery (grades I and II) and those that are unlikely to recover (grade III). Nevertheless, repeated tests over time can show whether improvement is occurring. Somatosensory evoked potentials are abnormal immediately following nerve injury; this a useful test for monitoring nerve function during surgery that might compromise the nerve.

Since the nerve fibers that control sweating (sympathetic fibers of peripheral nerves, part of the autonomic nervous system) are most resistant to mechanical trauma, the skin supplied by the injured nerve may be examined using a magnifying lens or light scope (ophthalmoscope) or with the "sweat test" or iodine starch test, to examine for patterns of sweating and to determine whether complete interruption of the nerve has occurred.

If the nerve injury resulted from trauma, x-rays, magnetic resonance imaging (MRI), and computed tomography (CT) scans may be performed to assess associated injury to bones, cartilage, muscles, tendons, and ligaments; this is especially important with nerve injuries originating close to the spine.

Source: Medical Disability Advisor



Treatment

The timing of treatment of open wound nerve injuries is critical. The wound is explored, and if a clean cut of the nerve is found, the proximal and distal nerve ends are matched and brought together so that microneurosurgical repair (neurorrhaphy) can be carried out. The goal of repair is to mend the ends of the nerve covering that contains the blood supply to the nerve (epineurium) so that new axonal nerve fibers can reconnect inside this covering (“Nerve Injuries”).

Repair may be done later; the timing of nerve repair is dictated by the nature of the nerve injury and may be performed after the wound has healed, when some of the swelling and scarring has resolved, and the wound is clean. Delayed repairs usually require nerve grafting using a piece of another nerve to bridge the injured area. Other surgical strategies may involve shortening a nearby bone to create relative length in the injured nerve if the nerve ends have retracted (Sharon).

In a closed injury (crush or shear), there is no indication for immediate surgery. However, the degree of nerve injury should be diagnosed as soon as possible. The individual is examined repeatedly over a 3-month period. During this period, gentle active motion of the involved extremity keeps the joints and soft tissue supple. The individual may be given medications (e.g., analgesics, anticonvulsants, corticosteroids) to control pain. If by 3 months there is some clinical or electrical evidence of recovery, the individual continues to be monitored. However, if there is no clinical or electrical (EMG) evidence of return of function at 3 months, the nerve is explored and tested. If the test indicates any activity across the injury, then corrective nerve surgery is performed. If there is no activity, the injured area is cut out (excised) and a graft is performed. If nerve repair is not possible, the surgeon may choose to alter the course of a tendon (tendon transfer) to improve function in the affected area (Sharon).

Source: Medical Disability Advisor



Prognosis

On average, the rate of axonal regeneration is 1 mm per day (Burnett). With grade I injuries, full recovery eventually will occur, although it may take many weeks (Sharon). During recovery from motor nerve injury, 70% of associated muscle fibers atrophy during the first 8 weeks, causing temporary weakness (Burnett). With grade II injuries, scarring will result in a less than perfect re-innervation with an extremely variable pattern. There is no recovery from grade III nerve injuries without surgical intervention; optimal outcomes are achieved with surgical repair within the first 3 months following injury (Sharon). The outcome also depends on the location and territory supplied by the injured nerve and on whether there is overlap in function with neighboring nerves that are not injured. In some cases, these nerves may be able to take over some functions of the injured nerves. Nerve injuries that occur at or close to the spine have a poor prognosis (Sharon).

Source: Medical Disability Advisor



Rehabilitation

Following nerve injury, physical therapy may be indicated to promote gradual recovery of muscle strength and to prevent contractures or stiffening of injured tissues and joints. Occupational therapy may help the individual regain independence in activities of daily living and may assist in selection and use of appropriate adaptive equipment. Vocational rehabilitation may help determine specific work restrictions and assist the individual in retraining for another job or in returning to work with modifications.

Source: Medical Disability Advisor



Complications

Open wounds may be complicated by wound infection and systemic infection (sepsis). Contractures of joints around the affected nerve may complicate motor nerve injury. Loss of sensation may lead to accidental burns or other injuries. Scarring may occur in and around the injured nerve, resulting in the formation of a neuroma. With imperfect healing, there may be paresthesias, changes in hot or cold sensitivity, weakness (paresis), or paralysis.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

The extent of injury, associated motor and sensory disability, and type of work will dictate the type of work restrictions or accommodations necessary. If a nerve injury requires surgery, individuals may need to immobilize the affected area to allow healing for approximately 3 weeks; if nerve grafting is necessary, immobilization will be needed for 4 weeks before initiation of physical therapy and gradual return to function (Sharon). Individuals may need time off for follow-up visits for clinical and electrodiagnostic examination throughout recovery (Sharon).

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Does individual have a history of trauma, surgery, or repetitive task-type injury to the affected area?
  • Does individual have complaints of pain, lack of sensation, increased sensitivity, or unpleasant sensation to the affected area?
  • Did the diagnostic workup include a neurosensory exam of the affected area?
  • Has the nerve injury been identified and quantified using electromyography and/or nerve conduction studies?
  • Were additional diagnostic studies, such as x-ray, MRI, or CT scan, done to rule out blood clot, foreign body, or other mass that could be interfering with nerve function and repair?

Regarding treatment:

  • Has surgical repair been considered? Should it be immediate or delayed?
  • Are associated injuries and underlying conditions being treated appropriately?
  • Might individual benefit from second opinion consultation to consider management strategies?
  • Has individual been receiving physical and occupational therapy? Is individual compliant?

Regarding prognosis:

  • Was there a prolonged time between the initial injury and the surgical repair?
  • Did individual experience any complications such as wound infection following surgery that could affect recovery and prognosis?
  • Has individual experienced associated muscle wasting or muscle contracture that could affect recovery and prognosis?

Source: Medical Disability Advisor



References

Cited

"Pathophysiology of Peripheral Nerve Injury: A Brief Review." Medscape Today. 2004. Medscape. 3 Sep. 2009 <http://www.medscape.com/viewarticle/480071>.

American Academy of Orthopaedic Surgeons. "Nerve Injuries." Your Orthopaedic Connection. Oct. 2007. American Academy of Orthopaedic Surgeons. 25 Aug. 2009 <http://orthoinfo.aaos.org/topic.cfm?topic=A00016>.

Burnett, Mark G., and E. L. Zager. "Pathophysiology of Peripheral Nerve Injury: A Brief Review." Neurosurgery Focus 16 5 (2004): NA. Medscape Today. Medscape. 3 Sep. 2009 <http://www.medscape.com/viewarticle/480071>.

Hyde, Thomas E. "Nerve Injury Classifications; Chapter 7 – Nerve Injuries in Competitive Sports." Conservative Management of Sports Injuries. Eds. Marianne S. Gegenbach, et al. Jones and Bartlett, 2007. 349-353.

Sharon, Idan, and Chaim I. Fishfeld. "Acute Nerve Injury." eMedicine. Eds. Duc Hoang Duong, et al. 14 Nov. 2007. Medscape. 25 Aug. 2009 <http://www.medscape.com/article/249621-overview>.

Source: Medical Disability Advisor






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