Significance of tortuous filling defects at lumbar myelography.

At lumbar myelography, tortuous filling defects frequently occur in the presence of a marked local narrowing of the spinal canal. This may lead to a displacement and compression of nerve roots, which may partially or completely fill the subarachnoid space. However, truly elongated nerve roots have also been observed, both at myelography and at operation. Such elongation appears to be a congenital malformation. The recognition of the true nature of tortuous filling defects is important with regard to differentiation against arteriovenous malformations and congested veins.