Application of Diffusion Tensor Imaging Cutoff Value to Evaluate the Severity and Postoperative Neurologic Recovery of Cervical Spondylotic Myelopathy.

BACKGROUND: Magnetic resonance imaging (MRI) plays an important role in the assessment of spinal cord status for cervical spondylotic myelopathy (CSM). Diffusion tensor imaging (DTI) also is a novel investigation tool with good sensitivity to detect changes in CSM, but it is not routinely used in spinal cord evaluation. METHODS: Sixty-six patients with CSM who required surgical decompression were included. All the patients were divided into 4 subgroups according to Japanese Orthopaedic Association (JOA) recovery rate. A 3.0T MR system was applied to obtain DTI of the spinal cord. Clinical assessment was performed with the JOA scores system. RESULTS: DTI data of 61 patients were available for further analysis in this study. No significant differences in age, sex, cervical curvature, surgical approach, and preoperative JOA score between the 4 subgroups were found (P > 0.05). Significant differences in apparent diffusion coefficient (ADC) (P < 0.0001), mean diffusivity (MD), (P < 0.0001), axial diffusivity (AD) (P = 0.0459), and radial diffusivity (RD) (P < 0.0001) values were found between the 4 groups. The ADC (P < 0.0001), MD (P < 0.0001), AD (P = 0.0434), and RD (P < 0.0001) values were significantly correlated with JOA recovery rate. Cutoff values of ADC, MD, AD, and RD in this study were 1.378*10-3, 1.378*10-3, 2.386*10-3, and 0.894*10-3 mm2/s, respectively. CONCLUSION: DTI was closely related to the severity of CSM, and cutoff values of DTI enabled the surgeons to predict the surgical outcomes in patients with CSM. These evaluation metrics may reflect the pathologic conditions of the spinal cord quantitatively, and potentially evaluate the functional status of spinal cords.

[Hidden blood loss after lumbar spinal stenosis operation].

OBJECTIVE: To determine the total blood loss and hidden blood loss associated with surgery for lumbar spinal stenosis and to identify risk factors for blood loss. METHODS: From September 2002 to July 2006, the clinical data from 138 patients with lumbar spinal stenosis undergoing initial operation were analysed prospectively. There were 44 males and 94 females, aging 56-78 years (mean 66.7 years). A simple posterior lumbar spinal decompression was used in 26 cases; posterior spinal canal decompression, interbody distraction Cage, and bone graft between transverse process was used in 54 cases; pedicle screw fixation, posterior decompression and bone graft between transverse process was used in 32 cases; posterior decompression, pedicle screw fixation, interbody Cage, and graft between transverse process was used in 26 cases. Before operation, 23 patients took aspirin, and after operation 15 patients had gastrointestinal bleeding. Intraoperative blood loss was calculated by the aspirator and observed blood loss intraoperation. The whole estimated blood loss was calculated according to the level of hemoglobin, blood volume and blood transfusion at the time of admission and after 3 and 4 days of operation. RESULTS: The blood loss intraoperation was (485.51 +/- 143.75) mL. The estimated blood loss was (1218.60 +/- 306.86) mL, which was significantly higher than the intraoperational blood loss (P < 0.001). There was significant difference between the estimated blood loss and observed blood loss during surgeries (P < 0.001). There were significant differences in the estimated blood loss and observed blood loss during surgery between patients treated with aspirin and without aspirin (P < 0.001), between patients with gastrointestinal bleeding and whiout gastrointestinal bleeding (P < 0.001). CONCLUSION: The total blood loss after surgery for lumbar spinal stenosis is much greater than that of observed intra-operation. The type of surgery, treatment with aspirin and gastrointestinal bleeding or ulceration can all independently increase blood loss.