Primary spread of caudal blockade in children: the possible limiting role of the lumbar spinal cord enlargement (tumenescence) in combination with the cerebrospinal fluid rebound mechanism.

The maximum of the lumbar spinal enlargement is located at the Th 11 vertebral level. Although not entirely conclusive, the findings of the present study do support the notion that the lumbar spinal enlargement, in combination with the CSF rebound mechanism, may be the factors limiting the initial spread of a caudal block to the thoraco-lumbar junction.