Pyogenic Epidural Abscess with Primary Erector Spinae Pyomyositis –Case Report

ABSTRACT

Pyogenic epidural abscess associated with primary pyomyositis of erector spinae in an immunocompetent individual is extremely rare. Here we report such a case which has been successfully managed.

A 26 year old man presented with severe pain in the low back region radiating to both the legs of 3 weeks duration. He was initially suspected to have prolapsed lumbar disc and treated conservatively without relief of symptoms. He had low grade fever on admission with no obvious systemic source of sepsis. Examination revealed only a positive straight leg raising test on both the sides with paravertebral muscle spasm and tenderness over the lumbar region without any other neurological deficit.

Laboratory results showed leucocytosis, neutrophilia, elevated erythrocyte sedimentation rate and C-reactive protein. Magnetic resonance imaging (MRI) of the spine with contrast revealed an extensive L3 –S1 epidural abscess with multiple loculated collection of pus in the erector spinae muscles suggestive of pyomyositis. Abscess from the lumbar paravertebral muscles was drained, L5 bilateral laminectomy was performed and extradural abscess was completely evacuated. Pain was completely relieved in the immediate post operative period. Culture revealed growth of staphylococcus aureus which was sensitive to most of the antibiotics except oxacillin. Patient was treated with intravenous vancomycin for 3 weeks which was followed by oral linezolid for 3 weeks combined with oral ofloxacin for 6 weeks. Follow up spinal MRI scan with contrast performed after 6 months was normal. There was no recurrence of symptoms even at the end of 7 months.

Pyogenic spinal infection associated with paraspinal muscle abscess must always be considered when back pain with leg pain is associated with fever, leucocytosis and elevated ESR. Staphylococcus aureus is the most common pathogen in these cases. Hematogenous spread of infection through the venous communication between the external vertebral venous plexus with the internal vertebral veins, resulting in simultaneous abscess formation in both the sites is the probable pathogenesis in our case. Early surgical drainage of the abscess from both the sites, with concurrent use of antibiotic therapy for 6 weeks based upon the sensitivity of the organism is required to achieve an excellent outcome.

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