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BioMed Research International
Volume 2016, Article ID 8163519, 9 pages
http://dx.doi.org/10.1155/2016/8163519
Research Article

Neural-Dural Transition at the Thoracic and Lumbar Spinal Nerve Roots: A Histological Study of Human Late-Stage Fetuses

1Department of Neurology, Wonkwang University School of Medicine and Hospital, Institute of Wonkwang Medical Science, Iksan 570-711, Republic of Korea
2Department of Anatomy, Histology and Embryology, Yanbian University Medical College, Yanji, Jilin, China
3Department of Anatomy, Akita University School of Medicine, Akita 010-8502, Japan
4Maxillofacial Anatomy, Department of Maxillofacial Biology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
5Division of Internal Medicine, Iwamizawa Kojin-kai Hospital, Iwamizawa 068-0833, Japan
6Department of Anatomy and Human Embryology, Institute of Embryology, Faculty of Medicine, Complutense University, Madrid, Spain

Received 8 December 2015; Accepted 31 January 2016

Academic Editor: Mohammadali M. Shoja

Copyright © 2016 Kwang Ho Cho et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Epidural blocks have been used extensively in infants. However, little histological information is available on the immature neural-dural transition. The neural-dural transition was histologically investigated in 12 late-stage (28–30 weeks) fetuses. The dural sheath of the spinal cord was observed to always continue along the nerve roots with varying thicknesses between specimens and segments, while the dorsal root ganglion sheath was usually very thin or unclear. Immature neural-dural transitions were associated with effective anesthesia. The posterior radicular artery was near the dorsal root ganglion and/or embedded in the nerve root, whereas the anterior radicular artery was separated from the nearest nerve root. The anterior radicular artery was not associated with the dural sheath but with thin mesenchymal tissue. The numbers of radicular arteries tended to become smaller in larger specimens. Likewise, larger specimens of the upper thoracic and lower lumbar segments did not show the artery. Therefore, elimination of the radicular arteries to form a single artery of Adamkiewicz was occurring in late-stage fetuses. The epidural space was filled with veins, and the loose tissue space extended ventrolaterally to the subpleural tissue between the ribs. Consequently, epidural blocks in infants require special attention although immature neural-dural transitions seemed to increase the effect.