Assessment of Posterior Globe Flattening: Two-Dimensional versus Three-Dimensional T2-Weighted Imaging

PURPOSE: To compare the frequency of posterior globe flattening between two-dimensional T2-weighted imaging (2D T2WI) and three-dimensional (3D T2WI). MATERIALS AND METHODS: Sixty-nine patients (31 female; mean age, 44.4 years) who had undergone both 5-mm axial T2WI and sagittal 3D 1-mm isovoxel T2WI of the whole brain for evaluation of various diseases (headache [n = 30], large hemorrhage [n = 19], large tumor or leptomeningeal tumor spread [n = 15], large infarct [n = 3], and bacterial meningitis [n = 2]) were used in this study. Two radiologists independently reviewed both sets of images at separate sessions. Axial T2WI and multi-planar imaging of 3D T2WI were visually assessed for the presence of globe flattening. The optic nerve sheath diameter (ONSD) was measured at a location 4 mm posterior to each globe on oblique coronal imaging reformatted from 3D T2WI. RESULTS: There were significantly more globes showing posterior flattening on 3D T2WI (105/138 [76.1%]) than on 2D T2WI (27/138 [19.6%], P = 0.001). Inter-observer agreement was excellent for both 2D T2WI and 3D T2WI (Cohen's kappa = 0.928 and 0.962, respectively). Intra-class correlation coefficient for the ONSD was almost perfect (Cohen's kappa = 0.839). The globes with posterior flattening had significantly larger ONSD than those without on both 2D and 3D T2WI (P < 0.001; 6.14 mm +/- 0.44 vs. 5.74 mm +/- 0.44 on 2D T2WI; 5.90 mm +/- 0.47 vs. 5.56 mm +/- 0.34 on 3D T2WI). Optic nerve protrusion was significantly more frequent on reformatted 1-mm 3D T2WI than on 5-mm 2D T2WI (8 out of 138 globes on 3D T2WI versus one on 2D T2WI; P = 0.018). CONCLUSION: Posterior globe flattening is more frequently observed on 3D T2WI than on 2D T2WI in patients suspected of having increased intracranial pressure. The globes with posterior flattening have significantly larger ONSD than those without.

Assessment of Autonomic Function in Post-Acute Ambulatory Patients with Mild or Moderate Traumatic Brain Injury Using the Analysis of Heart Rate Variability / 신경정신의학

OBJECTIVES: Autonomic nerve system dysfunction has been reported in patients following traumatic brain injury (TBI). However, studies providing direct evidence of a link between the two have been scarce. The purpose of the present study was to evaluate cardiac autonomic modulation in post-acute ambulatory outpatients with TBI using an analysis of heart rate variability (HRV). METHODS: Twenty-one patients with TBI and 21 age- and gender-matched normal controls were evaluated. The HRV assessments were performed using conventional time and frequency domain analyses as well as non-linear complexity analysis. RESULTS: In the patient group, standard deviation values of the RR intervals (SDNN), the square root of the mean squared differences of successive normal sinus intervals (RMSSD), total successive RR interval difference (TSRD), and the very low frequency (VLF) power spectral parameter were significantly lower than in the control group. The patients with moderate severity of TBI exhibited a significantly lower value of VLF than those with mild severity. The severity of anxiety symptoms had a tendency to be correlated with the mean heart rate and the ratio of low-to-high frequency spectral power. CONCLUSION: The results of the present study provide evidence that TBI is associated with reduced HRV, suggesting the critical involvement of central autonomic structures in the pathogenesis of TBI. The HRV measures may serve as an index for monitoring aspects of autonomic function in patients with TBI.