Rare cause of back pain: Staphylococcus aureus vertebral osteomyelitis complicated by recurrent epidural abscess and severe sepsis

Abstract

An epidural abscess represents a rare acute medical emergency, with a reported incidence of 2.5/10 000 hospital admissions annually. The clinical features include fever, spinal pain, radiating nerve root pain and leg weakness. When sepsis is present, prompt recognition is required to initiate appropriate antimicrobial therapy and surgical decompression. We present the case of a man aged 68 years presenting to the emergency department with a 3-day history of fever, low back, right hip and leg pain. He was hypoxic, tachycardic and hypotensive. He required intubation and ventilation. An MRI spine confirmed a posterior epidural abscess from T12 to L4. Blood cultures revealed Staphylococcus aureus He started treatment with linezolid and underwent incision and drainage. He remained septic and 8 days later, a repeat MRI spine showed a peripherally enhancing posterior epidural collection from L2/L3 to L4/L5, consistent with a recurrent epidural abscess. Further drainage was performed. He developed bilateral knee pain requiring washout. His right knee synovial biopsy cultured S. aureus He continued treatment with linezolid for 6 weeks until his C reactive protein was 0.8 ng/L. He started neurorehabilitation. 10 weeks later, he became feverish with lumbar spine tenderness. An MRI spine showed discitis of the L5/S1 endplate. A CT-guided biopsy confirmed discitis and osteomyelitis. Histology was positive for S. aureus and he started treatment with oral linezolid. After 19 days, he was discharged with 1 week of oral linezolid 600 mg 2 times per day, followed by 1 further week of oral clindamycin 600 mg 4 times daily. This case report reinforces the importance of maintaining a high clinical suspicion, with a prompt diagnosis and combined medical and surgical treatment to prevent adverse outcomes in this patient cohort. With spinal surgical services centralised, physicians may not encounter this clinical diagnosis more often in day-to-day hospital medical practice. The unique aspect of this case is the persistence and then the recurrence (despite 6 weeks of antimicrobial therapy and a second debridement) of S. aureus infection. Furthermore, the paucity of clinical recommendations and the controversy regarding the adequate duration of antimicrobial therapy are notable features of this case.

Figure 1

Chest radiograph showed atelectasis within the lung bases bilaterally.

Figure 2

Unenhanced CT head. An unenhanced CT head showed no evidence of intracranial bleed, extracerebral collection or focal mass lesion.

Figure 3

MRI head with contrast. An MRI head with contrast displayed no evidence of leptomeningeal disease.

Figure 4

MRI whole spine with contrast. An MRI spine demonstrated normal alignment and vertebral body height. A posterior epidural collection extending from T12 to L4 was observed.

Figure 5

Mobile image intensifer lumbar spine demonstrated the epidural abscess intraoperatively.

Figure 6

MRI whole spine with contrast. An epidural abscess from L2/L3 to L4/L5 causing significant central canal stenosis and distortion of the cauda equine was observed as well as progressive discitis at L2/L3 and L5/S1.

Figure 7

CT thorax, abdomen and pelvis showed destruction of the L5/S1 endplate consistent with known discitis.

Figure 8

MRI whole spine with contrast demonstrated extensive areas of pathological enhancement within the interspinous ligaments between L3 and L5, the inferior vertebral endplates of L2, L5 and S1 vertebral bodies, the sacral canal and the perivertebral soft tissues mainly at L5 and S1 levels, in keeping with an ongoing infectious/inflammatory process.

Figure 9

CT-guided biopsy of L5–S1. He underwent a CT-guided biopsy, using an 11 G core biopsy of his right-sided L5–S1 disc.