Four days after a left total hip arthroplasty, an obese 62-year-old woman develops severe back pain in the region of the epidural block. The pain progresses with radicular pain down the leg over 72 hours. The most likely diagnosis is

Four days after a left total hip arthroplasty, an obese 62-year-old woman develops severe back pain in the region of the epidural block. The pain progresses with radicular pain down the leg over 72 hours. The most likely diagnosis is

• A. Epidural abscess
• B. Epidural hematoma
• C. Anterior spinal artery syndrome
• D. Arachnoiditis

Answer: (A)

New, severe back pain after neuraxial instrumentation that progresses with leg radicular pain over a few days points most strongly to an epidural abscess. An abscess in the epidural space forms a space-occupying infection that gradually enlarges and compresses adjacent nerve roots, causing escalating pain and radiating symptoms down the leg. Obesity is a risk factor because it can be associated with impaired wound healing and infection. Fever and rising inflammatory markers may be present, but can be absent early, so imaging is crucial when new neurologic-type pain develops after a neuraxial block. Epidural hematoma would more typically cause rapid neurologic deterioration soon after catheter placement or after anticoagulation, not a subacute, days-to-week progression. Anterior spinal artery syndrome presents with bilateral motor and pain/temperature loss due to vascular occlusion and has a different pattern and timeline. Arachnoiditis generally causes chronic, often diffuse radicular pain that develops over months rather than days after the procedure. Urgent MRI of the spine with gadolinium is needed to confirm an epidural abscess, followed by prompt surgical drainage and antibiotics.

New, severe back pain after neuraxial instrumentation that progresses with leg radicular pain over a few days points most strongly to an epidural abscess. An abscess in the epidural space forms a space-occupying infection that gradually enlarges and compresses adjacent nerve roots, causing escalating pain and radiating symptoms down the leg. Obesity is a risk factor because it can be associated with impaired wound healing and infection. Fever and rising inflammatory markers may be present, but can be absent early, so imaging is crucial when new neurologic-type pain develops after a neuraxial block.

Epidural hematoma would more typically cause rapid neurologic deterioration soon after catheter placement or after anticoagulation, not a subacute, days-to-week progression. Anterior spinal artery syndrome presents with bilateral motor and pain/temperature loss due to vascular occlusion and has a different pattern and timeline. Arachnoiditis generally causes chronic, often diffuse radicular pain that develops over months rather than days after the procedure.

Urgent MRI of the spine with gadolinium is needed to confirm an epidural abscess, followed by prompt surgical drainage and antibiotics.