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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.

Tetanus


Text Only Home | Graphic-Rich Site | Overview | Risk and Causation | Diagnosis | Treatment | Prognosis | Differential Diagnosis | Specialists | Comorbid Conditions | Complications | Factors Influencing Duration | Length of Disability | Ability to Work | Maximum Medical Improvement | Failure to Recover | Medical Codes | References

Medical Codes

ICD-9-CM:
037 - Tetanus

Related Terms

  • Lockjaw
  • Pott’s Disease

Overview

Tetanus is a serious, potentially fatal disease of the central nervous system caused when a wound becomes infected by the bacteria Clostridium tetani, which releases a potent neurotoxin. The disease is characterized by muscle rigidity (hypertonia) and numerous muscle spasms, and autonomic nervous system dysfunction. Often, the first sign is stiffness of the jaw muscles (trismus), hence the synonym lockjaw. Tetanus has an incubation period of 1 to 55 days, with more than 80% of cases reporting symptoms within 14 days. The shorter the incubation period, the more serious and life-threatening the disease.

C. tetani spores are commonly found in the soil. These bacteria are also found in the intestines of domestic animals. As a result, soil contaminated with manure is especially likely to contain these spores. The spores enter the body through breaks in the skin or wounds, particularly deep puncture wounds. They multiply in wounds where little oxygen is available, producing a poison (neurotoxin) that travels to the central nervous system. There it interferes with the functioning of the nerves that control muscle activity, causing severe muscle spasms. Tetanus has become a rare disease in industrialized countries since the introduction of widespread immunization.

Incidence and Prevalence: In the US, during 2001-2008, 233 cases were reported; there were 26 deaths among the 197 cases with reported outcome (13.2%); 29 cases of tetanus are reported each year (range: 19-40) ("Tetanus Surveillance"). Worldwide, tetanus is predominantly a disease of underdeveloped countries in warm, damp climates. Contributing factors include a very low rate of immunization, poor waste treatment, poor hygiene and wound care, and use of untreated animal manure for fertilizer. Tetanus is one of the target diseases of the World Health Organization Expanded Program on Immunization. Overall annual worldwide incidence is 0.5 million to 1 million cases (Hinfey).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Lack of immunization is the highest risk factor in contracting tetanus. In the US, about 87% of cases occur in individuals who have not been adequately immunized. Tetanus affects all age groups, although the very young and those over age 65 are at higher risk ("Tetanus Surveillance"). In the US, 59% of cases and 75% of deaths occur in individuals over age 60 (Hinfey).

Men and women are affected equally.

Farmers and other individuals who live in rural areas of the South where they are more likely to come into contact with animal manure are at higher risk. Tetanus is much rarer in cold climates than in warm, humid environments. Intravenous drug use, frostbite, skin ulcers, surgical wounds, traumatic wounds, and burns increase one's risk of contracting tetanus.

Source: Medical Disability Advisor



Diagnosis

History: Early symptoms are sore throat with difficulty in swallowing (dysphagia). The hallmark symptoms of tetanus are spasms and stiffness of the jaw (trismus or lockjaw) (50-75% of cases (Hinfey)), making it difficult or even impossible to open the mouth. Other symptoms include restlessness, stiff neck, drooling, stiffness in abdominal and back muscles, reflex spasms, and contraction of facial muscles into a fixed, excited expression, with elevation of eyebrows (risus sardonicus). There may also be a fever, profuse sweating, restlessness, headaches, and painful muscle spasms. Seizures often occur in response to sensory stimuli (noise, light, changes in temperature). Spasms of the respiratory muscles may inhibit normal breathing.

Physical exam: The exam may reveal a painful or tender wound. However, a wound may not be apparent in as many as 35% of cases (Hinfey). Muscle rigidity and spasm, increased heart rate (tachycardia) or slow heart rate (bradycardia), irregular heartbeat (arrhythmia), drooling, irritability, and increased blood pressure (hypertension) alternating with hypotension may be noted. Spasm of the muscles along the spine causes a posture of arching of the back and neck called opisthotonos. The individual's color may appear bluish or gray (cyanosis) as a result of inadequate oxygen. The individual remains awake and alert throughout the illness.

Tests: Tetanus is diagnosed on the basis of presenting symptoms. No specific laboratory test exists. Although the organism can sometimes be cultured from a wound, false negative cultures occur about one-third of the time. Electromyography (EMG) may be used to analyze the electrical activity of the muscles. Lumbar puncture may be done to eliminate a diagnosis of meningitis. A computed tomography (CT) scan may be used to eliminate a diagnosis of brain abnormalities, and a serum calcium level can rule out the diagnosis of hypocalcemia.

Source: Medical Disability Advisor



Treatment

Tetanus infection is serious and life-threatening. Treatment is usually administered in the intensive care unit (ICU) of a hospital and has four goals: stabilization and support of the patient as symptoms develop, administration of tetanus immunoglobulin (TIG) to help moderate the effects of the toxin, administration of antibiotics to kill the C. tetani bacteria, and prophylactic immunization to prevent future occurrence.

An open airway must be maintained. Depending on the individual's symptoms, this may be done by different methods. A tube may be inserted into the windpipe (trachea) in a procedure called intubation. However intubation is difficult as a consequence of laryngeal muscles spasm, and the presence of an endotracheal tube may be a stimulus for further spasms; hence, in severe cases an artificial opening in the trachea (tracheostomy) may be required. If the individual is unable to breathe independently, ventilation may be required. Nutritional support may need to be provided through a feeding tube or through parenteral (intravenous) nutrition. The wound is cleaned thoroughly; damaged tissue may need to be surgically removed (débridement). Antibiotics such as metronidazole are administered to eradicate the toxin-producing organisms. TIG is also administered to neutralize unbound (free) toxin (antitoxin can't neutralize toxin already bonded to nerve tissue). Anticonvulsants may be necessary to control the seizures. Muscle relaxants and sedatives may also be prescribed.

Prophylaxis against pneumonia, deep-vein thrombosis (DVT), and thromboembolism is essential.

Because having tetanus does not grant further immunity against the infection, after recovery the individual should receive the full series of vaccinations.

Source: Medical Disability Advisor



Prognosis

Acute respiratory failure is the leading cause of death in tetanus infections. A short incubation period is associated with a particularly grim prognosis. The overall mortality rate ranges from less than 10% in cases of mild tetanus to as high as 50% in severe cases with sudden onset (Hinfey). High mortality rates are also associated with early onset of convulsions, individuals who require mechanical ventilation, or delay in treatment. Contaminated wounds located on the head and face are more dangerous than wounds located on other parts of the body. The individual's age and severity of symptoms also affect prognosis. Recovery is complete if the individual survives the infection.

Source: Medical Disability Advisor



Differential Diagnosis

Source: Medical Disability Advisor



Specialists

  • Cardiovascular Internist
  • General Surgeon
  • Infectious Disease Internist
  • Internal Medicine Physician
  • Neurologist
  • Pulmonologist

Source: Medical Disability Advisor



Comorbid Conditions

  • Cardiovascular disease
  • Compromised immune system
  • Pulmonary disease

Source: Medical Disability Advisor



Complications

Complications include inability to breathe (respiratory failure), heart failure, tachycardia, blood clots to the lungs (pulmonary emboli), pulmonary edema, other secondary bacterial infections, dehydration, bone fractures secondary to spasms and/or seizures, airway obstruction, suffocation, urinary retention, kidney failure, constipation, bronchiolitis, destruction of muscle tissue (rhabdomyolysis), coma, and death.

Source: Medical Disability Advisor



Factors Influencing Duration

Length of disability may be influenced by the severity of the illness, location of wounds, promptness and adequacy of treatment, presence of complications, and age of the individual.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Upon returning to work, strenuous activity or work requiring heavy lifting may need to be modified until physical stamina returns.

Risk: Tetanus is not spread from individual to individual; therefore, there is no risk to coworkers from the infected individual. Individuals working in at-risk professions (e.g., farmers, animal handlers) should be regularly immunized against the disease to prevent infection.

Capacity: Capacity is affected by the speed and effectiveness of treatment and whether acute respiratory failure occurs. During treatment, individuals will need an extended leave of absence until the infection resolves.

Tolerance: Tolerance is typically not an issue with this disease. Infected individuals will be treated in the ICU and will be unable to work until recovery is complete. The presence of Pott’s disease could alter capacity and tolerance.

Source: Medical Disability Advisor



Maximum Medical Improvement

90 days.

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:

  • Has diagnosis of tetanus been confirmed?
  • Have other conditions, such as strychnine poisoning, dental infection, acute drug reaction to phenothiazines, meningoencephalitis, hepatic encephalopathy, rabies, subarachnoid hemorrhage, seizure disorder, alcohol withdrawal, peritonsillar abscess, or hypocalcemic tetany, that cause similar symptoms to tetanus been ruled out?
  • Has individual experienced any complications such as respiratory arrest, heart failure, pulmonary emboli, other bacterial infection, dehydration, spine or other bones fracture, airway obstruction, suffocation, urinary retention, constipation, pneumonia, destruction of muscle tissue, or coma?
  • Does individual have an underlying condition such as advanced age or preexisting heart disease that may affect recovery?

Regarding treatment:

  • Was individual hospitalized?
  • Did individual receive prompt administration of tetanus antitoxin or tetanus immune globulin?
  • Were antibiotics and antitoxins given to eradicate the toxin-producing organisms?
  • Were anticonvulsants and muscle relaxants needed to control the seizures?
  • Was intubation, tracheostomy, or mechanical ventilation necessary?
  • Did individual experience any complications related to these procedures?
  • Was surgical débridement of wound required?
  • Is wound now healing adequately? If not, what further procedures may be required?

Regarding prognosis:

  • Are any of these risk factors (a short incubation period, early onset of convulsions, need for mechanical ventilation, or delay in treatment) relevant to individual's case?
  • Where was the wound located?
  • Is individual over 65 years of age?

Source: Medical Disability Advisor



References

Cited

"Tetanus Surveillance --- United States, 2001--2008." CDC. 1 Apr. 2011. Centers for Disease Control and Prevention. 14 Jul. 2015 <http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6012a1.htm>.

Hinfey, Patrick B. "Tetanus." eMedicine. 17 Jun. 2015. Medscape. 14 Jul. 2015 <http://emedicine.medscape.com/article/229594-overview#a0156>.

General

Roper, M. H. "Tetanus Prophylaxis in the Emergency Department." Annals of Emergency Medicine 43 3 (2004): 305-314.

Source: Medical Disability Advisor