Morphological features and clinical significance of epidural membrane in the cervical spine.
METHODS
A prospective clinical study.


OBJECTIVE
To elucidate the histomorphological features and clinical significance of the epidural membrane (EM) in the cervical spine based on operative and histological findings.


BACKGROUND
The anatomical features of the EM have been mostly discussed on the basis of cadaver studies in the whole spine. However, the histomorphological features and clinical significance of the EM in the cervical spine based on operative findings have never been reported.


METHODS
Eighty-seven patients with cervical spondylotic myelopathy who had undergone an expansive open-door laminoplasty under microscopy were evaluated with a more than 2-year follow-up period. The most damaged spinal segment was determined in each patient from the preoperative neurological and image findings along with the remaining symptoms at follow-up. The morphological features of the EM were observed and recorded in each patient during decompression. For histology, specimens of common and remarkable types of the EM obtained from 16 patients were examined.


RESULTS
The age at surgery averaged 64.5 years; there were 58 men and 29 women. With regard to the most damaged spinal segment, there were 14 cases at the C3-C4 level, 37 at the C4-C5 level, 32 at the C5-C6 level, and 4 at the C6-C7 level. The EM was an adipo-fibro-vascular tissue with various histomorphologies, blending with the periradicular sheath. Some EMs showed notable findings: obstructing dural tube expansion (13 cases, 14.9%), compressing a nerve root or disturbing its mobility (4 cases, 4.6%), and the combined type (1 case, 1.1%). All of them were located at approximately the most damaged spinal segment. In addition, some EMs had interesting histological features, such as harboring many small arteries, calcified debris, and metaplastic bone fragments.


CONCLUSIONS
The EM can develop into remarkable structures with spondylosis and aging in patients with cervical spondylotic myelopathy, affecting surgical outcomes as well as successful decompression procedures. A sound understanding of the histomorphological features of the EM is required to obtain satisfactory surgical outcomes in the limited field afforded by minimally invasive surgery.
Department of Orthopaedic Surgery, Hiroshima City Asa Hospital, Hiroshima, Japan. akiramchi@yahoo.co.jp
Akira
A
Miyauchi
Tadayoshi
T
Sumida
Hideki
H
Manabe
Yukio
Y
Mikami
Mayumi
M
Kaneko
Yoshio
Y
Sumen
Mitsuo
M
Ochi
D000368:Aged; D002574:Cervical Vertebrae / Q000601:surgery*; D019299:Decompression, Surgical; D004388:Dura Mater / Q000473:pathology / Q000601:surgery; D004564:Electrocoagulation; D004824:Epidural Space; D005260:Female; D005355:Fibrosis; D006801:Humans; D017843:Ligamentum Flavum / Q000473:pathology / Q000601:surgery; D008297:Male; D008566:Membranes / Q000098:blood supply / Q000502:physiology / Q000601:surgery / Q000648:ultrastructure*; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D009408:Nerve Compression Syndromes / Q000209:etiology / Q000601:surgery; D011183:Postoperative Complications / Q000517:prevention & control; D011446:Prospective Studies; D013115:Spinal Canal / Q000648:ultrastructure*; D013126:Spinal Nerve Roots; D013130:Spinal Stenosis / Q000150:complications / Q000473:pathology / Q000601:surgery; D055009:Spondylosis / Q000150:complications / Q000473:pathology / Q000601:surgery