Muscle Musculoskeletal

The mode of action of many skeletal muscle relaxants, for example carisoprodol (Soma), baclofen (Lioresal), and chlorzoxazone (Paraflex), is not clearly understood. Many of tiiese dragp do not directly relax skeletal muscles, but dieir ability to relieve acute painful musculoskeletal conditions may be due to their sedative action. Cyclobenzaprine (Flexeril) appears to have an effect on muscle tone, tiius reducing muscle spasm. 

The exact mode of action of diazepam (Valium), an antianxiety drug (see Chap. 30), in die relief of painful musculoskeletal conditions is unknown. The drug does have a sedative action, which may account for some of its ability to relieve muscle spasm and pain. 

Skeletal muscle relaxants are used in various acute, painful musculoskeletal conditions, such as muscle strains and back pain. 

Drowsiness is the most common reaction seen with the use of skeletal muscle relaxants. Additional adverse reactions are given in die Summary Drug Table Drugp Used to Treat Musculoskeletal Disorders. Some of the adverse reactions tiiat may be seen with the administration of diazepam include drowsiness, sedation, sleepiness, letiiargy, constipation or diarrhea, bradycardia or tachycardia, and rash. 

The musculoskeletal system consists of bones, blood vessels, nerves, ligaments, tendons, muscles, and cartilage, which work together to perform the structural and kinematic functions of the organism. These musculoskeletal tissues all have a composite structure of cells embedded in a matrix produced by the cells themselves. 

Musculoskeletal Effects. No studies were located regarding musculoskeletal effects in humans after inhalation exposure to trichloroethylene. Trichloroethylene exposure can result in nervous system effects that result in secondary effects on muscle strength, especially in the face (Leandri et al. 1995). See Section 2.2.1.4 for further discussion of nervous system effects following trichloroethylene exposure. 

Cardiovascular Increased stroke index, heart rate, and diastolic and mean arterial pressures Musculoskeletal Bone pain, muscle weakness Dermatologic Pruritus... 

The musculoskeletal system consists of the muscles, bones, joints, tendons, and ligaments. Disorders related to the musculoskeletal system often are classified by etiology. Acute soft-tissue injuries include strains and sprains of muscles and ligaments. Repeated movements in sports, exercise, work, or activities of daily living may lead to repetitive strain injury, where cumulative damage occurs to the muscles, ligaments, or tendons.1-3 While tendonitis and bursitis can arise from acute injury, more commonly these conditions occur as a result of chronic stress.3,4 Other forms of chronic musculoskeletal pain, such as pain from rheumatoid arthritis (see Chap. 54) or osteoarthritis (see Chap. 55), are discussed elsewhere in this text. 

Where pain is worsened by muscle spasm, oral muscle relaxants may serve as a useful adjunct to therapy.25 These agents include baclofen, metaxalone, methocarbamol, carisoprodol, and cyclobenzaprine. Muscle relaxants may decrease spasm and stiffness associated with either acute or chronic musculoskeletal disorders. These agents should be used with caution because they all may cause sedation, especially in combination with alcohol or narcotic analgesics. 

Physical examination of the musculoskeletal system (e.g., biceps, triceps, quadriceps, temporalis, deltoid, and interosseus muscles) for loss of muscle mass, and examination of the skin and mucous membranes for abnormalities (e.g., noting dry or flaky skin, bruising, edema, ascites, poorly healing wounds) and loss of subcutaneous fat... 

No gross or histological alterations in skeletal muscle were observed in rabbits exposed to 1,000 mg/kg/day of cyclotriphosphazene (Kinkead et al. 1989c, 1990) or in rabbits exposed to an unspecified amount of Cellulube 220 (Carpenter et al. 1959). Both of these studies were intermediate-duration dermal exposure studies. Studies examining musculoskeletal end points following acute- or chronic-duration exposure were not located. 

Musculoskeletal Effects. Individuals who have had high exposures to lead, either occupationally or by the consumption of alcohol from lead stills, have been reported to exhibit a bluish-tinged line in the gums (i.e., the "lead line"). In addition, case reports of high occupational exposure to lead have described the occurrence of muscle weakness, cramps, and joint pain. 

Musculoskeletal Effects. Neither inhalation nor oral exposures to hexachloroethane were associated with histopathological changes in skeletal muscle or bone in rats following acute-, intermediate-, or chronic-duration exposures with inhalation exposure concentrations of 15-5,900 ppm or oral exposure doses of... 

Musculoskeletal Effects. Muscle wasting and atrophy have been reported in humans occupationally exposed to n-hexane (Yamamura 1969). These effects occurred in individuals with severe neurotoxicity. 

Musculoskeletal Effects. Muscle wasting and atrophy have been reported in humans occupationally exposed to -hexane (Yamamura 1969). These effects occurred in individuals with severe neurotoxicity. Muscle atrophy is a common finding after intermediate-duration inhalation exposure to n-hcxanc in experimental animals. This atrophy is secondary to i -hexane-induccd neurotoxicity which results in... 

Musculoskeletal Effects. Muscular rigidity was observed in humans after acute cyanide poisoning (Grandas et al. 1989) and rhabdomyolysis, a clinical syndrome characterized by skeletal muscle injury, was observed in a man who ingested 0.57 mg CNVkg in a suicide attempt (Saincher et al. 1994). 

Musculoskeletal Effects. No gross or histological lesions were found in bones or skeletal muscle of rats exposed intermittently to <1.4 mg/m for 13 weeks (Shiotsuka 1989). 

Musculoskeletal Effects. A case of muscle pain and weakness was described in an individual after intermittent chronic inhalation and dermal exposure to vapors and solutions of phenol, cresol, and xylenol (Merliss 1972). The symptoms lessened when the subject was removed from exposure. 

Musculoskeletal Effects. Muscle pain in the arms and legs was reported in a case of chronic phenol poisoning (Merliss 1972). The man worked in a laboratory for 13.5 years where he distilled phenol several times a day. During the process, heavy odors were detectable, phenol was often spilled on his clothes, and he noted skin irritation. The man recovered after 2-3 months away from the exposure. 

Musculoskeletal Effects. Both patients described by Letz et al. (1984) (see Section 2.2.3.1) had greatly elevated levels of serum creatinine phosphokinase after 1,2-dibromoethane exposure this enzyme increases in the event of skeletal muscle necrosis. There was no report of skeletal muscle being examined at necropsy or histologically in either individual. 

Musculoskeletal Effects. Dramatic musculoskeletal effects as evidenced by elevated muscle enzymes in serum occurred in two patients exposed by the dermal and inhalation routes (Letz et al. 1984). No musculoskeletal effects were reported in humans exposed by other routes or in experimental animals. Risks appear to be negligible for adverse musculoskeletal effects in humans exposed to low levels of 1,2-dibromoethane. 

Gastrointestinal Nausea, vomiting, diarrhea, dry mouth, lump in throat, butterflies Musculoskeletal Restlessness, muscle tension, pacing, muscle pain Neurological Dizziness, lightheadedness, fainting, headache, tremulousness, tingling... 

One study was located which examined the musculoskeletal effects in laboratory animals after inhalation exposure to 1,4-diehlorobenzene. No gross or histological alterations in skeletal muscle (unspecified parameters) were detected in rats exposed to 1,4-diehlorobenzene at air concentrations of up to 490-499 ppm, 5 hours a day, 5 days a week for 76 weeks (Riley et al. 1980). 

Musculoskeletal/Cardiac effects When serum sodium or calcium concentration is reduced, moderate elevation of serum potassium may cause toxic effects on the heart and skeletal muscle. Weakness and later paralysis of voluntary muscles, with consequent respiratory distress and dysphagia, are generally late signs, sometimes significantly preceding dangerous or fatal cardiac toxicity. 

---