A 52-yr-old man presented with right groin and back pain associated with nausea, vomiting, chills, discolored urine, and difficulty voiding. On admission, the patient had a temperature of 99.5° F and a white blood cell count of 17,900. A computed tomographic urogram showed multiple bilateral small renal calculi with associated hydronephrosis. He subsequently had a right ureteric stone removal with stent placement.
The day after surgery, the patient complained of numbness in his legs, generalized weakness, and difficulty ambulating. He continued to complain of significant back pain and difficulty voiding. On neurologic evaluation, he was found to have mild bilateral lower limb weakness. The patient had a history of recent intravenous drug abuse, and an magnetic resonance imaging of the brain and lumbar spine were performed to rule out any central pathology. Magnetic resonance imaging of the lumbar spine with and without contrast revealed an infectious process, including abscesses in the right psoas and right erector spinae musculature with epidural phlegmon extending from L2 through S1. There was severe spinal canal stenosis with compression of the cauda equina at levels L2–S1 (Fig. 1).
The patient underwent L2–L5 bilateral decompressive laminectomies, bilateral foraminectomies and evacuation of the epidural/paraspinal abscesses. Cultures obtained from the abscess grew methicillin-sensitive Staphylococcus aureus. After 4 wks of antibiotic treatment, the patient’s symptoms improved, and he was able to ambulate 100 ft during his physical therapy session.
Psoas abscesses, spinal epidural abscesses, and vertebral osteomyelitis are interrelated infections. Each shares the same risk factors and may result from a local contiguous source or from hematogenous dissemination.1 Ten percent to 30% of spinal epidural abscesses result from direct extension of local infection, and in this case, from a psoas abscess.2 The thoracic and lumbar areas are the most likely sites of involvement.3 Risk factors for psoas abscesses are intravenous drug use, vascular catheters, and immunosuppression.2 The most commonly cultured organism is S. aureus.3
Patients with psoas and epidural abscesses frequently present with fever, back pain, and neurologic deficits.4 Patients may complain of pain in the hip and thigh because the psoas muscle is innervated by L1, L2, and L3 nerve roots. Imaging investigations such as computed tomography and magnetic resonance imaging are helpful in making a definitive diagnosis. Treatment includes surgical drainage and theadministration of an antibiotic regimen directed at the inciting organisms.1
1. Baron MJ, Kasper DL: Intraabdominal infections and abscesses. Harrisons Princ Intern Med
2008; 121: 813
2. Siddiq F, Chowfin A, Tight R, et al.: Medical vs. surgical management of spinal epidural abscess. Arch Intern Med
2004; 164: 2409–12
3. Darouiche R: Spinal epidural abscess. N Engl J Med
2006; 355: 2012–20
4. Sendi P, Bregenzer T, Zimmer I: Spinal epidural abscess in clinical practice. QJM
2008; 101: 1–12