Radiographical presentations of inadvertent subdural placement of an epidural catheter for successful labor analgesia: A case report

Abstract

Rationale: Lumbar epidural analgesia is the gold standard for labor pain control. However, misplacement of epidural catheters into the subdural space may inadvertently happen. Unrecognized subdural administration of local anesthetics could result in serious consequences, including high spinal and brainstem blocks. This case report describes a case where subdural epidural catheter placement was recognized early but labor pain was adequately managed by dosage titration of subdural analgesia. Patient concerns: This case report describes a 29-year-old primiparous pregnant woman who was admitted to our obstetric unit for labor induction at the gestational age of 38 weeks. An epidural catheter was inserted via the L2-3 intervertebral space using the standard loss of resistance to air technique. Diagnoses: The parturient experienced weakness in the lower extremities and numbness in the upper extremities within 15 minutes after administration of 5 mL of 2% v/v lidocaine as a loading dose and systolic blood pressure also dropped by 25%. Interventions: The dose regimen (a mixture of 0.1% ropivacaine and 4 μg/mL fentanyl) for patient-controlled analgesia was given with bolus doses of 0.1 mL per demand and lockout intervals of 20 minutes. The analgesic effects were adequately maintained below the T8 dermatome for more than 12 hours without hypotensive episodes or obvious signs of neurological deficits. Computed tomographic myelography was performed by instillation of a nonionic iodinated contrast medium via the epidural catheter on postpartum day 2 for imaging confirmation of catheter placement in the extradural space. Lessons: Early recognition that epidural catheters for neuraxial analgesia have been inserted into the subdural space is important for the prevention of high spinal blocks. Subdural analgesia could still be achieved by careful clinical assessment and titration of low analgesic doses. This report also presents important and clear serial computed tomographic images of catheter placement in the thoracic-lumbar subdural spaces and the extent of volume spread in the subdural space following administration of contrast medium.