Distinguishing Pseudomeningocele, Epidural Hematoma, and Postoperative Infection on Postoperative MRI.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To identify specific magnetic resonance imaging (MRI) characteristics of epidural fluid collections associated with infection, hematoma, or cerebrospinal fluid (CSF). SUMMARY OF BACKGROUND DATA: Interpretation of postoperative MRI can be challenging after lumbar fusion. The purpose of this study was to identify specific MRI characteristics of epidural fluid collections associated with infection, hematoma, or CSF. METHODS: The study population includes consecutive patients between 2006 and 2010 who had MRIs performed within 2 weeks after elective surgery for evaluation of possible CSF fluid collection, hematoma, or infection. Patients with known previous infection (discitis/osteomyelitis) or inadequate MRIs were excluded from the study. Medical records were reviewed to determine the diagnosis (infection, hematoma, or pseudomeningocele) underlying the fluid collection. MRIs were retrospectively evaluated by a musculoskeletal radiologist and orthopedic spine attending who were blinded to the pathologic diagnosis for characteristics of the fluid collection. MRI characteristics include location of lesion: osseous involvement, disk location, anterior versus posterior versus anteroposterior, soft-tissue involvement, and iliopsoas involvement. Characteristics of the lesion include: volume of lesion, loculation, satellite lesions, multiple loci, destructive characteristics, and mass effect upon thecal sac. Enhancement was scored based upon the following variables: rim enhancement, smooth versus irregular, thin versus thick, heterogeneity, diffuse enhancement, nonenhancement, and rim thickness. General fluid collection intensity and complexity on T1, T2, and T1 postcontrast images was scored as high, medium, and low. The χ test was used to compare the incidence of imaging characteristics between patient groups (infection, hematoma, and CSF). RESULTS: Thirty-three patients were identified who met inclusion criteria. There were 13 (39%) with infection, 9 (27%) with hematoma, and 11 (33%) with CSF collection. Factors that were associated with infection were osseous involvement (R=0.392, P=0.024) and destructive characteristics (R=0.461, P=0.007). Factors that were correlated with hematoma include mass effect (R=0.515, P=0.002) and high T1-signal intensity (R=0.411, P=0.019), absence of thecal sac communication (R=-0.389, P=0.025), and absence of disk involvement (R=-0.346, P=0.048). Pseudomeningocele was associated with thecal sac communication (R=0.404, P=0.02), absence of mass effect (R=-0.48, P=0.005), low T1 signal (R=-0.364, P=0.04), and low T2 complexity (R=-0.479, P=0.005). CONCLUSION: Specific characteristics of the postoperative MRI can be used to distinguish infection from noninfectious fluid collections. The strongest predictors of infection were osseous involvement and destructive bony changes. Hematoma was associated with mass effect on the thecal sac, high T1-signal intensity, and absence of thecal sac communication and disk involvement. CSF collections were distinguished by absence of mass effect, low T2-signal complexity, low T1-signal intensity, and communication with the thecal sac.

Change in Angular Alignment Is Associated With Early Dysphagia After Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective analysis of a prospective cohort. OBJECTIVE: Change in cervical angular alignment may be associated with dysphagia. SUMMARY OF BACKGROUND DATA: Bony deformities of the cervical spine may be associated with secondary contractures of soft tissues in the neck. Acute surgical deformity correction causes in changes in soft tissue tension in the anterior neck, resulting in dysphagia. METHODS: The study population included patients undergoing 1 and 2 level elective anterior cervical discectomy and fusion for cervical myelopathy or radiculopathy. Preoperative and postoperative radiographs at 2 weeks were measured by a blinded observer for C2-C7 endplate angle, C2-C7 posterior vertebral body length, and occipital condyle plumb line distance on upright lateral radiographs at 2, 6, and 12 weeks postoperatively. Patients were prospectively queried about dysphagia incidence and severity using a numeric rating scale. Multiple linear regression analysis was used to determine the effect of change in radiographic parameters controlling for demographic characteristics. RESULTS: The study population included 25 patients with complete radiographs. The mean change in C2-C7 angle was -0.6 degrees (SD 9), the mean change in C2-C7 length was 1.7 mm (SD 26), the mean change in occipital condyle plumb line distance was 2.3 mm (SD 20).Multiple linear regression analysis was performed including operative time, age, sex, number of levels, and change in radiographic parameters as independent variables and using dysphagia score as the dependent variable. The change in C2-C7 angle and operative time were the only statistically significant predictors of change in dysphagia at 2 and 6 weeks postoperatively. CONCLUSIONS: These results indicate that lordotic change in spinal alignment and longer operative times are associated with increased postoperative dysphagia. Surgeons should counsel patients in whom a large angular correction is expected about the possibility for postoperative dysphagia. Furthermore, future studies on dysphagia incidence should include radiographic alignment as an independent predictor of dysphagia.

Complications of Flat Bed Rest After Incidental Durotomy.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To determine whether bed rest is a risk factor for specific medical complications. SUMMARY OF BACKGROUND DATA: Flat bed rest after incidental durotomy is commonly used to reduce the risk of CSF leakage and associated complications. METHODS: Retrospective case series of consecutive patients after lumbar laminectomy were identified. Medical records were reviewed for duration of bed rest and complications (pulmonary, wound, neurological, gastrointestinal, and urinary) in the chart notes, repair methods, subfascial drain placement, consultant notes, imaging reports, and discharge summaries. Patients were compared with duration of bed rest >24 hours versus duration of bed rest ≤24 hours. The incidence of complications was compared between groups using the Fisher exact test. RESULTS: There were a total of 42 patients with incidental durotomy. There were 18 patients in the bed rest ≤24 hours group and 24 patients in the bed rest >24 hours group. Comparing the bed rest ≤24 hours to bed rest >24 hours patients, there was no statistically significant difference in the incidence of postdurotomy-related neurological complications, wound complications, and need for revision surgery. There was a statistically significant decrease in the incidence of total medical complications in the ≤24-hour group (0% vs. 50%, P=0.0003). CONCLUSION: There was an increased incidence of medical complications in the bed rest group >24 hours. Flat bed rest after modern dural repair method may not be a necessity in all cases and may be associated with a higher incidence of medical complications.