An Uncommon Cause Of Back Pain - Page #4

Working Diagnosis:
MSSA bacteremia with left paraspinous lumbar pyomyositis associated with mild acute renal insufficiency.

The patient was admitted to the hospital for empiric treatment with IV vancomycin, ceftriaxone, and IV fluids. When blood cultures revealed MSSA, antibiotics were changed to oxacillin. Repeat blood cultures were negative. A repeat total spine MRI showed possible abscess formation along the posterior aspect of the left L2-L3 facet joint (1.0 x 0.4 cm) and in the left paraspinal musculature at the L2-L3 level (1.2 x 0.5 cm). The Orthopaedic Surgery team did not recommend drainage. The patient was discharged home on hospital day five with a nafcillin infusion to complete a ten-day course of IV antibiotics. He was pain-free at discharge, but restricted from all football activities initially.

The patient was able to return to playing football a little less than 2 months after his initial injury.

Author's Comments:
This patient, presumably, had a left paraspinous muscle hematoma at the site of helmet trauma that was seeded by a subsequent transient bacteremia resulting in pyomyositis. Pyomyositis is an infection of skeletal muscle that is usually, but not always, associated with abscess formation. The most common pathogen causing pyomyositis is Staphlococcus aureus. Infection is typically spread hematogenously. Skeletal muscle trauma, including irritation from vigorous exercise is a preceeding risk factor. In bacteremic settings, injured muscle cells are at increased risk of becoming infected. This case highlights a rare but potentially life-threatening complication of skeletal muscle injury.

Editor's Comments:
Pyomyositis is more commonly seen in the tropics but can also be seen in adults in more temperate climates. Along with the risk factors of vigorous exercise and trauma seen in this case, it is important to note that the majority of cases seen in temperate climates are associated with immunocompromise. Therefore, patients should be screened for HIV, diabetes, or malignancy. Injection drug use is also a risk factor.
Additionally, because pyomyositis is a disease of hematogenous spread, patients should also be evaluated for other disease processes associated with bacteremia such as endocarditis.

1. Abu Hassan, F. et al. Primary Myositis of the Paraspinal Muscles: A Case Report and Literature Review. Europe Spine Journal. A239-42 (Suppl 2) 2008.

2. Crum, N.F. Bacterial pyomyositis in the United States. American Journal of Medicine. 117(6)420-428. 2004.

3. Jayoussi, R et al. Pyomyositis caused by vigorous exercise in a boy. Acta Paediatrics. 84:226-7. 1995.

5. Lo, T.S. et al. Pyomyositis complicating acute bacterial endocarditis in an intravenous drug user. New England Journal of Medicine. 342: 1614-15. 2000

5. Meehan, J et al. Pyomyositis in an Adolescent Female Athlete. Journal of Pedaitric Surgery. 30(1)127-8. 1995.

6. Spiegel, D et al. Pyomyositis in Children and Adolescents: Report of 12 Cases and Review of the Literature. Journal of Pediatric Orthopaedics. 19(2)143-50. 1999.

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