Clinicopathological study of "snake-eye appearance" in compressive myelopathy of the cervical spinal cord.
OBJECTIVE
The goal of this study was to elucidate the pathophysiological features and clinical significance of the magnetic resonance imaging-documented small intramedullary high signal intensity known as "snake-eye appearance" (SEA) in cases of compressive myelopathy such as cervical spondylosis or ossification of the posterior longitudinal ligament.


METHODS
One hundred forty-four patients with compression myelopathy who underwent surgery between 1998 and 2000 were selected. Intramedullary high signal intensity was found in 79 cases and was divided into two types, SEA and non-SEA (NSEA). The Japan Orthopaedic Association (JOA) scoring system was used for evaluation of pre- and postoperative neurological status. In nine cases of SEA autopsy was performed and specimens were histologically analyzed. The improvement ratio determined by JOA score was 32.2 +/- 15.1% in SEA, 47.1 +/- 12.1% in NSEA, and 50 +/- 18.3% (p < 0.01) in control cases in which high signal intesity was absent. There were significant differences among SEA, NSEA, and control groups. In a separate group of nine patients who died of unrelated causes, histological examination showed small cystic necrosis in the center of the central gray matter of the ventrolateral posterior column and significant neuronal loss in the flattened anterior horn.


CONCLUSIONS
Snake-eye appearance was found to be a product of cystic necrosis resulting from mechanical compression and venous infarction. Destruction of the gray matter accompanying significant neuronal loss in the anterior horn suggested that SEA is an unfavorable prognostic factor for the recovery of upper-extremity motor weakness.
Mizuno
Junichi
J
Department of Neurological Surgery, Institute for Medical Science of Aging, Aichi Medical University, Aichi-gun, Aichi, Japan. jmizuno@amugw.aichi-med-u.ac.jp
Nakagawa
Hiroshi
H
Inoue
Tatsushi
T
Hashizume
Yoshio
Y
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae; D005260:Female; D006801:Humans; D007796:Laminectomy; D017846:Longitudinal Ligaments / Q000473:pathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000175:diagnosis* / Q000601:surgery; D013116:Spinal Cord / Q000473:pathology; D013117:Spinal Cord Compression / Q000175:diagnosis* / Q000601:surgery; D013123:Spinal Fusion; D013128:Spinal Osteophytosis / Q000175:diagnosis* / Q000601:surgery; D016896:Treatment Outcome