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| IMAGE QUIZ ARCHIVE | ||||||
| Image Quiz | ||
| Acute Severe Hip and Thigh Pain in a Five-Year-Old Girl1 (continued) |
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| Answer: Streptococcal necrotizing myositis | ||
| Discussion | ||
| At surgery, the gluteus maximus appeared normal, but the gluteus medius and gluteus minimus were grossly swollen and a dull red color. Normal contractility and capillary bleeding of these two muscles were absent. No abscess was found. A radical excision of the gluteus medius and gluteus minimus was performed. Neither arthrotomy nor aspiration of the left hip joint was performed because the hip had appeared normal on magnetic resonance imaging. Following débridement, the blood pressure improved slightly to 85/45 mm Hg, and the patient was transferred to the intensive-care unit, where she required ventilator and vasopressor support. | ||
| A pure growth of Streptococcus pyogenes that was sensitive to penicillin G and clindamycin grew on culture of muscle specimens and blood. Specimens obtained with swabs from the throat and nose of the patient and the other family members were negative for Streptococcus pyogenes. Histological examination of the excised muscles showed extensive tissue necrosis and heavy suppurative inflammation, mainly affecting the fibrous septa between the muscle bundles and in the fascial tissue. | ||
| In contrast to pyomyositis, an infection of skeletal muscle that is caused predominantly by Staphylococcus aureus and is associated with a mortality rate of <1%2,3, streptococcal necrotizing myositis is a rare but much more severe infection that is associated with a mortality rate between 50% and 100%4-11. In the literature, this severe infection usually has been referred to as streptococcal myositis; however, we prefer to use the term streptococcal necrotizing myositis because extensive muscle necrosis is common, even in the early stages of the disease12. | ||
| Infective myositis, including streptococcal necrotizing myositis and pyomyositis, poses a diagnostic challenge to the clinician8. The symptoms and signs of myositis can be nonspecific and misleading, not clearly revealing the involvement of deep skeletal muscle. The skin overlying the infected muscles usually appears normal until a very late stage. This "silent" external appearance is in contrast to the severe pain and extreme tenderness of the affected area. Pain that is out of proportion to the physical appearance typically has been described with this condition2,8,13. The clinical presentation may be confused with that of other conditions, such as septic arthritis and deep-vein thrombosis. In this five-year-old girl, the severe pain and tenderness, the global decrease in the range of motion of the left hip, and the diffuse soft-tissue swelling made a diagnosis of septic arthritis unlikely. These physical findings, together with the toxic appearance of the patient and the findings on the anteroposterior radiographs, resulted in the diagnosis of streptococcal necrotizing myositis. | ||
| It is important to differentiate streptococcal necrotizing myositis from pyomyositis because urgent surgical exploration can be lifesaving for the patient with streptococcal infection, whereas more conservative methods can be used for the patient with pyomyositis. Clinically, the early and rapid development of severe pain and tenderness is more suggestive of streptococcal necrotizing myositis. The rapid downhill course is in contrast to that seen in pyomyositis, which can take up to three weeks to progress from the initial "invasive stage" to the "late stage."2 The early development of toxic systemic involvement (streptococcal toxic-shock syndrome14) is typical of streptococcal necrotizing myositis. It is important to note, however, that children are able to compensate well initially but that their condition may deteriorate suddenly. | ||
| With our patient, the involvement of muscles was seen on the plain radiographs. To delineate the exact extent of muscle involvement, we performed an emergent magnetic resonance imaging scan. While other imaging techniques such as computed tomography and ultrasonography are more readily available and can provide similar information more quickly15, their smaller field of view does not give the surgeon as extensive a view of the infected area. The interpretation of ultrasound images is also more operator-dependent. Moreover, the use of a scanning probe on an exquisitely tender area is usually unacceptable to the patient, especially a child. Compared with computerized tomography magnetic resonance imaging offers certain advantages, such as the ability to perform multiplanar imaging and to obtain better resolution and contrast in delineating soft-tissue lesions16,17. | ||
| The involvement of two adjacent muscles, as seen on magnetic resonance imaging, is more suggestive of an infectious etiology than of other causes of myositis, such as hemorrhage or infarction. Magnetic resonance imaging also helps to differentiate streptococcal necrotizing myositis from pyomyositis. The magnetic resonance imaging criteria for the diagnosis of pyomyositis are well documented3. In our patient, the magnetic resonance imaging features of the involved glutei were different from those described for pyomyositis. With pyomyositis, liquefaction of the infected muscles form an abscess, but this is not a feature of streptococcal necrotizing myositis. The magnetic resonance imaging findings associated with pyomyositis, such as rim enhancement of the infected area on contrast-medium-enhanced T1-weighted images and high-signal-intensity fluid collection on T2-weighted images, are therefore absent on the magnetic resonance images of patients with streptococcal necrotizing myositis. Adjacent reactive joint effusion, another common finding on magnetic resonance images of patients with pyomyositis, was also absent in our patient, probably because of the much shorter duration of the disease process. The emergent magnetic resonance imaging also helped to exclude other diagnoses, especially septic arthritis. Had magnetic resonance imaging not been available, an arthrocentesis might have been required before the diagnosis of septic arthritis could be confidently excluded, and the virulent Streptococcus pyogenes might have been introduced into the sterile hip joint. | ||
| Prompt and radical débridement is the key to the survival of a patient with streptococcal necrotizing myositis9. We recommend surgical exploration after the diagnosis has been made. Because the findings on magnetic resonance imaging clearly showed that the left hip joint was not involved, exploration of the joint was deemed unnecessary and we were able to achieve a complete, radical débridement. The extent of débridement must be guided both by magnetic resonance imaging and intraoperative findings. | ||
| References | ||
| 1. Tang WM, Wong JW, Wong LL, Leong JC. Streptococcal necrotizing myositis: the role of magnetic resonance imaging. A case report. J Bone Joint Surg Am. 2001;83:1723-6. 2. Chiedozi LC. Pyomyositis. Review of 205 cases in 112 patients. Am J Surg. 1979;137:255-9. 3. Gordon BA, Martinez S, Collins AJ. Pyomyositis: characteristics at CT and MR imaging. Radiology. 1995;197:279-86. 4. Adams EM, Gudmundsson S, Yocum DE, Haselby RC, Craig WA, Sundstrom WR. Streptococcal myositis. Arch Intern Med. 1985;145:1020-3. 5. Boyle MF, Singer J. Necrotizing myositis and toxic strep syndrome in a pediatric patient. J Emerg Med. 1992;10:577-9. 6. Hird B, Byrne K. Gangrenous streptococcal myositis: case report. J Trauma. 1994;36:589-91. 7. Jansen JE, Retpen JA. Acute spontaneous streptococcal myositis. Case report. Acta Chir Scand. 1988;154:323-4. 8. Kang N, Antonopoulos D, Khanna A. A case of streptococcal myositis (misdiagnosed as hamstring injury). J Accid Emerg Med. 1998;15:425-6. 9. Marck KW, den Hollander H, Grond AJ, Veenendaal D. Survival after necrotising streptococcal myositis: a matter of hours. Eur J Surg. 1996;162:981-3. 10. Nather A, Wong FY, Balasubramaniam P, Pang M. Streptococcal necrotizing myositis: a rare entity. A report of two cases. Clin Orthop. 1987;215:206-11. 11. Schattner A, Hay E, Lifschitz-Mercer B, Gorbacz S, Bentwich Z. Fulminant streptococcal myositis. Ann Emerg Med. 1989;18:320-2. 12. Stevens DL. Streptococcal toxic shock syndrome associated with necrotizing fasciitis. Annu Rev Med. 2000;51:271-88. 13. Green RJ, Dafoe DC, Raffin TA. Necrotizing fasciitis. Chest. 1996;110:219-29. 14. The Working Group on Severe Streptococcal Infections. Defining the group A streptococcal toxic shock syndrome. Rationale and consensus definition. JAMA. 1993;269:390-1. 15. Jacobson JA, van Holsbeeck MT. Musculoskeletal ultrasonography. Orthop Clin North Am. 1998;29:135-67. 16. Kilcoyne RF, Richardson ML, Porter BA, Olson DO, Greenlee TK, Lanzer W. Magnetic resonance imaging of soft tissue masses. Clin Orthop. 1988;228:13-9. 17. Murphy WA, Totty WG. Musculoskeletal magnetic resonance imaging. Magn Reson Annu. 1986;1-35. |
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