Perineural hematoma following lumbar transforaminal steroid injection causing acute-on-chronic lumbar radiculopathy: a case report.

INTRODUCTION: Transforaminal epidural steroid injections (TFESI) are commonly performed for the treatment of lumbar herniated nucleus pulposus and lumbosacral radiculopathy. Although rare, documented complications including spinal cord infarction, paraparesis, epidural abscess, paraplegia, and epidural hematoma have been reported. Here, we present a case of perineural hematoma affecting the L4 nerve root resulting in progressive acute-on-chronic lumbar radiculopathy following TFESI. CASE REPORT: A 72-year-old female presented with 3 months of low back and right anterior thigh pain. She subsequently underwent right L3 and L4 TFESI for physical examination findings concordant with radiographic right foraminal stenosis at L3-4 and L4-5 with L3-4 spondylolisthesis. Over the following week, the patient reported progressive right lower extremity weakness, worsening sensory loss, and ambulatory dysfunction. Examination revealed mild L3/4 myotomal weakness, sensory changes, and areflexia at the right patella. A gadolinium-enhanced MRI was ordered, which showed focal abnormal signal with involvement of the right L4-L5 neuroforamina and extending slightly far laterally, consistent with a small hematoma, affecting the L4 nerve root. Within 2 months, her strength and reflexes normalized and sensory loss diminished following medical management. DISCUSSION: Although extremely rare, perineural or foraminal hematomas may occur as a serious complication of TFESI, even in the setting of a standardized procedure. Hematoma may cause worsening of symptoms in the acute and subacute phase following TFESI. Further investigation into the etiologies of such injuries is warranted and must be added to the considerations of pain physicians performing these procedures.