Perineural hematoma following lumbar injection presenting as a neurosurgical emergency.

Lower back pain and sciatica account for approximately 40% of work-related absences, with management options ranging from conservative measures, such as rest and analgesia, to surgical intervention. Lumbar epidural steroid injections and facet joint blocks are frequently used for both diagnostic and therapeutic purposes. While most complications are minor (2.4%-9.6%), severe events, including infection, hematoma formation, and spinal cord infarction, have been reported. This case presents a perineural hematoma manifesting as acute radiculopathy, necessitating urgent surgical decompression. The patient was a 55-year-old woman with a 7-month history of low back pain radiating to her right leg, unresponsive to conservative treatments, who subsequently underwent facet and nerve root injections. Magnetic resonance imaging demonstrated lumbar degeneration with Modic changes and multilevel disc bulging. The procedure, performed under fluoroscopic guidance with contrast and therapeutic agents, was initially uneventful. However, on the third day post-injection, she developed acute left leg weakness and sensory impairment. Repeat magnetic resonance imaging showed an abnormal signal in the left L3-L4 foramen compressing the L3 nerve root, raising suspicion for a perineural hematoma. Urgent surgical decompression was performed, and pathological examination confirmed organizing hemorrhage. The patient's neurological symptoms improved rapidly, with complete recovery achieved within a month. The literature indicates that hematomas may arise from increased epidural pressure or direct needle injury, even in the absence of signs of bleeding. Practitioners should remain vigilant for post-injection hematomas, as delayed recognition can result in permanent neurological deficits. Magnetic resonance imaging is essential for timely diagnosis, and urgent decompression may optimize outcomes, given that earlier intervention is associated with better recovery.