Adult tethered cord syndrome: relative to spinal cord length and filum thickness

The adults with tethered cord syndrome (TCS) are divided into two groups: group-1 adult TCS patients with spinal dysraphism; and group-2 patients without dysraphism who develop signs and symptoms in adulthood. A significant number of group-2 patients failed to show elongation of the spinal cord and abnormally thick filum terminale. This paper reports the combinations of the location of the caudal end of the spinal cord and the thickness of the filum terminale in 104 patients with group-2 adult TCS. The caudal end of the spinal cord was found at the L2-3 intervertebral space or above in 37 patients (35.6%) and below L2-3 level in 67 patients (64.4%). The diameter of the filum was <2 mm in 60 patients (57.7%) and > or =2 mm in 44 patients (42.3%). These data clearly indicate that the pre-operative diagnosis of adult TCS must rely primarily on the neurological symptomatology and the specific imaging feature, posterior displacement of the conus and filum that attach the posterior arachnid membrane.