Clinical significance of diffusion tensor tractography as a predictor of functional recovery after laminoplasty in patients with cervical compressive myelopathy.
OBJECTIVE
This study was conducted to determine whether postoperative changes in the fractional anisotropy (FA) value and diffusion tensor imaging of the cervical spinal cord can predict functional outcome for patients with cervical compressive myelopathy (CCM).


METHODS
Twenty patients with CCM were treated by laminoplasty from 2008 to 2009. Both T2-weighted MRI and diffusion tensor imaging were performed before and after surgery. The FA values were analyzed and fiber tracking was performed. The fiber tract (FT) ratio was calculated according to the following formula: (number of fibers at the compressed level)/(number of fibers at the C-2 level) × 100%. The Japanese Orthopaedic Association scoring system for cervical myelopathy was used to determine pre- and postoperative neurological status of the patients, and the Hirabayashi method was used to calculate the recovery rate.


RESULTS
There was no significant difference in recovery rates between patients with and those without intramedullary high signal intensity on preoperative T2-weighted images. Substantial differences in FA value among spinal cord, bone, and CSF made it difficult to obtain a precise FA value for the compressed spinal cord. There was a significant correlation between the preoperative FT ratio and the recovery rate (p = 0.0006). A poor outcome (recovery rate < 40%) could be anticipated for CCM patients with preoperative FT ratios below 60%.


CONCLUSIONS
The preoperative FT ratio correlated significantly with the recovery rates in CCM patients. Preoperative diffusion tensor tractography can be a new prognostic predictor for neurological recovery in CCM patients after laminoplasty.
Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan. masa@sc.itc.keio.ac.jp
Masaya
M
Nakamura
Kanehiro
K
Fujiyoshi
Osahiko
O
Tsuji
Tsunehiko
T
Konomi
Naobumi
N
Hosogane
Kota
K
Watanabe
Takashi
T
Tsuji
Ken
K
Ishii
Suketaka
S
Momoshima
Yoshiaki
Y
Toyama
Kazuhiro
K
Chiba
Morio
M
Matsumoto
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D002574:Cervical Vertebrae / Q000601:surgery*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D005544:Forecasting / Q000379:methods; D006801:Humans; D007796:Laminectomy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D020127:Recovery of Function; D013116:Spinal Cord / Q000503:physiopathology*; D013117:Spinal Cord Compression / Q000601:surgery*; D016896:Treatment Outcome