Anorectal Pressure Monitoring During Surgery for Reuntethering of the Spinal Cord in Cases of Lumbosacral Lipomyelomeningocele

Tethered cord syndrome is most often seen in children with a lumbosacral lipomyelomeningocele associated with occult spinal dysraphism, and often manifests as urinary bladder dysfunction, sensory disturbance, and motor weakness or deformity of the lower extremities. The aim of surgical treatment of a lipomyelomeningocele is to release the tethered spinal cord from the lipomatous tissue. Despite the satisfactory results obtained through surgical treatment for lumbosacral lipomyelomeningoceles without anorectal pressure monitoring [2], we found that untethering of the spinal cord was quite difficult to perform in some patients in which the lipoma involved the ventral part of the spinal cord [1, 4, 9]. We also found that appropriate repair of a lipomyelomeningocele at the time of initial surgery sometimes failed to prevent retethering of the spinal cord due to postoperative adhesion between the cord and the surrounding structures [1, 5], and that dissection of the neural structure deeply embedded in dense scar tissue was much more difficult to perform in a repeat operation for reuntethering of the spinal cord than in the initial operation. In such cases, intraoperative monitoring for identification of the nerve root and the conus medullaris is necessary to un-tether the spinal cord completely and preserve the neural structures. During the operation, the lower lumbar and first sacral ventral roots were easily identified by applying electrical nerve stimulation and palpating contractions of the segmental muscle groups. Identification of the second, third, and fourth sacral roots, which have neurogenic control of the urinary bladder and also the anal sphincter, requires measurement of sphincter function [3, 7, 8].