Spinal epidural abscesses after lumbar facet joint injections are rare but can cause rapid neurological deterioration. We describe a man in his 70s who developed severe lower back pain, fever, urinary retention, saddle anesthesia, and worsening paraparesis within two weeks of undergoing lumbar medial branch radiofrequency ablation for facet-mediated pain. Magnetic resonance imaging (MRI) revealed a posterior epidural collection at L4/5–L5/S1 with facet joint effusions and early spondylodiscitis, consistent with a spinal epidural abscess causing cauda equina compression. He received urgent intravenous flucloxacillin and underwent multidisciplinary review. Because of frailty, comorbidity, and early clinical improvement, the patient was managed non-operatively with prolonged antimicrobial therapy and rehabilitation. Follow-up imaging showed marked radiological improvement; however, the patient had persistent bilateral lower limb weakness with imaging features suggestive of probable post-infective arachnoiditis.

Spinal epidural abscess, Cauda equina syndrome, Radiofrequency ablation, Lumbar facet joint, Spondylodiscitis, Interventional pain medicine