Tethered cord. Tethered spinal cords are a group of complex developmental malformations of the spinal cord of which the most common cause is children with repaired spina-bifida or myelomeningocele. Although these are usually operated on shortly after birth, all repaired myelomeningoceles have some degree of tethering. The basic problem is exacerbated because as children grow their spinal cords do not grow as quickly as their spinal columns, so the spinal cord must be able to freely ascend on the inside of the spinal column during growth. If various abnormal structures are holding onto the spinal cord from below it stretches the spinal cord, leading to chronic local ischaemia, which can in turn lead to a progressive loss of function. The signs and symptoms associated with cord tethering are often non-specific and are poorly understood. Diffusion MRI may be very useful in the monitoring of tethered cords since initial studies on adults with cervical spondylosis have implied that it is more sensitive than conventional MRI imaging in depicting pathological changes within the spinal cord. Hence diffusion MRI has the potential to be a more sensitive method of determining if the cord is under stress due to tethering and hence in need of surgery.