Nerve fibre counts for an intercostal nerve to cauda equina nerve root anastomosis.

Mean nerve root diameters of thoracal, lumbal and sacral roots have been determined and the corresponding cross section areas calculated. The myelinated axons of these roots have been counted and the axon densities calculated. The myelinated axons of 3 lower intercostal nerves have also been counted. One intercostal nerve has with about 9,000 myelinated fibres enough axons for the regeneration of the ventral (3,000) and dorsal (16,000) myelinated fibres of the sacral roots 3 and 4 together. One intercostal has enough nerve fibres to reconstruct urinary bladder and bowel function on one side. The importance of performing a nerve anastomosis which considers functional aspects has been emphasized.