After the brain is removed, the entire spinal cord including cauda equina, dura, and dorsal root ganglia is removed using the standard posterior approach. Prior to turning the body, the most rostral aspect of the cervical cord is loosened from the spinal canal at the level of the foramen magnum (after brain removal) and is cut and removed separately to avoid pulling of the cord and consequent “toothpaste” artifact. The body is then turned and the entire spinal cord, cauda equina, dura, and dorsal root ganglia are removed. After removal, the length and diameter of the cord is measured and recorded, and each segment of the cord is dissected in order to obtain fresh frozen cord. The spinal cord is cut midway through the lumbar enlargement (L3-S1), as identified by enlarged motor rootlets, which approximates L4-5 levels. A 4 mm thick block of lumbar spinal cord is taken from both sides of this incision and is fixed. The rostral lumbar and caudal adjacent 0.4 cm are frozen. A similar procedure is used for the cervical and thoracic cord in order
