Mixed pyogenic and tuberculous spinal epidural abscesses perforating the dura and extending into the subdural space: A case report and review of the literature

Abstract

Background: Spinal infections are associated with a wide variety of clinical conditions, including osteomyelitis, spondylitis, diskitis, septic facet joints, and abscesses. Based on its anatomical relationship with the dura mater, the abscess can be epidural (extradural) or subdural (intrathecal). Subdural intramedullary abscesses of the lumbar spinal canal are more common than subdural extramedullary abscesses. Here, we present a rare case of a patient with a mixed pyogenic and tuberculous epidural abscess in the lumbar spine, which perforated the dura and extended to the subdural space.

Case description: A 29-year-old male presented with progressively worsening back pain and lower-limb weakness over a period of 3 months, with an associated inability to walk, intermittent radicular pain primarily on the left side, intermittent incontinence, and a history of low-grade fever and night sweats. The patient had a history of intravenous (IV) drug abuse and reported practicing unprotected sexual intercourse. Furthermore, the patient had recently came into contact with a person diagnosed with tuberculosis (TB). The patient was administered empirical broad-spectrum antibiotics and underwent emergent L4-L5 laminectomy and spinal abscess decompression. IV antibiotics were selected based on culture results, and anti-TB medications were started. Postoperatively, the patient demonstrated a remarkable lower-limb power improvement and radicular pain alleviation.

Conclusion: Spinal epidural abscess perforation of the dura and extension into the subdural space is extremely rare. Distinguishing between epidural and subdural abscesses radiologically is challenging. Multiple risk factors, such as unprotected sexual contact and IV drug misuse, may be associated with the development of polymicrobial abscesses in the lumbar spine. Careful anticipation, identification, and isolation of the causative micro-organisms can ensure effective antibacterial treatment. Early diagnosis, expeditious surgical decompression, and antibiotic treatment are associated with promising outcomes.

Keywords: Epidural abscess; Pyogenic spinal infection; Spinal infection; Spinal tuberculosis; Subdural abscess.

Figure 1:

Radiology: Spondylodiscitis with epidural and paraspinal abscess. (a1-a3) Sagittal T2WI of the lumbar spine shows multiple abnormal marrow signals involving the vertebral body and endplates of L2, L4, L5, and S1 with disc degeneration at L5/S1. There is an associated abnormal large ventral and dorsal epidural and paraspinal components compressing the thecal sac and cauda equina nerve roots. Sagittal (b1-b3) and axial (c1 and c2) WI show abnormal post contrast enhancement of the vertebral bodies and end-plated and marginal enhancement of the large epidural and paraspinal abscesses with extension against the neural foramen. (d) Sagittal T2WI of the cervical spine shows abnormal signal intensity of the upper cervical spine C2/3 and T5 suggesting noncontiguous infection. (e) A sagittal post contrast study shows abnormal vertebral with associated mild prevertebral and ventral epidural enhancement suggesting an infective process.

Figure 2:

(a and b) Epidural and subdural multi-layered inflamed nonpurulent soft-tissue/phlegmon perforating the dura and extending into the subdural space. (b and c) A thick, inflamed, and intact arachnoid layer. (d) White-yellow liquor puris purulent fluid pus discharge contained within a thin encapsulated membrane.

Figure 3:

Pathology: low power ×4 (a) and high power ×20 (b), shows a well-formed necrotizing (caseating) granuloma with central necrosis, surrounded by epithelioid histiocyte and lymphocyte. Special stains (not shown here) for Mycobacterium [Ziehl-Neelsen stain (ZN)] and fungal infection [Grocott methenamine silver (GMS) stain] are negative (these studies are for screening purposes. Negativity for these stains does not rule out the possibility of such infection).