Saccular Limited Dorsal Myeloschisis with a Short Stalk at the Base of the Sac Causing Spinal Cord Deviation out of the Spinal Canal

Saccular limited dorsal myeloschisis is a condition in which the spinal cord is tethered by a fibroneural stalk that links the cord to a saccular skin lesion, probably due to a small segmental failure of the disjunction between the neural and cutaneous ectoderm during primary neurulation. We previously reported that the dorsally bent cord deviated from the canal into the sac when the tethering effect of the limited dorsal myeloschisis stalk was strong. These cases of saccular limited dorsal myeloschisis should be prenatally differentiated from myelomeningoceles; however, this is complicated by the limited resolution of prenatal magnetic resonance imaging. Nevertheless, postnatal magnetic resonance imaging, including three-dimensional heavily T2-weighted imaging, to demonstrate the stalk linking the top of the bent cord to the sac dome is essential. We recently treated a patient who presented with a cord deviation to the sac due to a short stalk linking the rostral part of the bent cord to the base of the sac. While the sagittal and axial views of three-dimensional heavily T2-weighted imaging alone were insufficient to visualize the short stalk, the coronal view clearly demonstrated that the stalk ran almost parallel to it. During surgery, untethering the cord and completely returning it to the canal is important.