Damage to the Dura

There are really two layers of closely applied membrane surrounding the cauda equina. The outer membrane is the thicker dura and within it is the more delicate arachnoid (see Figure 6.1). If both are cut or torn, it is immediately obvious because there is a leak of clear cerebro-spinal fluid into the wound. If the dura alone is incised there will be no leak of cerebro-spinal fluid, but the arachnoid will bulge through the gaping dura.