Conus hematoma following spinal anesthesia in an unrecognized case of occult spinal dysraphism: Lessons from a rare but preventable iatrogenic injury

Background: Neurological complications following spinal anesthesia are uncommon. However, intramedullary conus hematomas may occur in patients undergoing epidural and spinal anesthesia with undocumented tethered cords, occult spinal dysraphism (OSD), and/or an abnormally low-lying conus medullaris. Case Description: A 28-year-old female developed a progressive left foot drop and urinary retention immediately after spinal anesthesia (i.e., lower-segment cesarean section). She had 2 findings consistent with an underlying dysraphic anomaly: a shaved lumbosacral patch/congenital tuft of hair and a longstanding pes cavus deformity. The magnetic resonance scan demonstrated a Type II split cord malformation with a tethered cord terminating at the L5 level. In addition, the spinal anesthetic caused a focal intramedullary conus hematoma. We elected to treat her nonsurgically, and 3 months later, with physical therapy (i.e., ankle-foot orthosis and bladder training), she progressively improved neurologically. Conclusion: Recognition of OSD/low-lying conus before spinal anesthesia would have avoided causing an intramedullary conus hematoma in this patient.