Effect of Age on Working Memory Performance and Cerebral Activation after Mild Traumatic Brain Injury: A Functional MR Imaging Study.

PURPOSE: To evaluate the age effect on working memory (WM) performance and functional activation after mild traumatic brain injury (MTBI). MATERIALS AND METHODS: This study was approved by the local research ethics committee. All participants provided written informed consent. N-back WM cerebral activation was assessed with functional magnetic resonance (MR) imaging in 13 younger (mean age, 26.2 years ± 2.9; range, 21-30 years) and 13 older (mean age, 57.8 years ± 6.6; range, 51-68 years) patients with MTBI and 26 age- and sex-matched control subjects. Two functional MR images were obtained within 1 month after injury and 6 weeks after the initial study. Group comparison and regression analysis were performed among postconcussion symptoms, neuropsychologic tests, and WM activity in both groups. RESULTS: In younger patients, initial hyperactivation was seen in the right precuneus and right inferior parietal gyrus (P = .047 and P = .025, respectively) in two-back greater than one-back conditions compared with younger control subjects, whereas in older patients, hypoactivation was seen in the right precuneus and right inferior frontal gyrus (P = .013 and P =.019, respectively) compared with older control subjects. Increased WM activity was associated with increased postconcussion symptoms in the right precuneus (r = 0.57; P = .026) and right inferior frontal gyrus (r = 0.60; P = .019) and poor WM performance in the right precuneus (r = -0.55; P = .027) in younger patients at initial studies but not in older patients. At follow-up examinations, partial recovery of activation pattern and decreased postconcussion symptoms (P = .04) were observed in younger patients but not in older patients. CONCLUSION: The different manifestations of postconcussion symptoms at functional MR imaging between younger and older patients confirmed the important role of age in the activation, modulation, and allocation of WM processing resources after MTBI. These findings also supported that younger patients have better neural plasticity and clinical recovery than do older patients.

Sex Differences in Working Memory after Mild Traumatic Brain Injury: A Functional MR Imaging Study.

PURPOSE: To evaluate sex differences in mild traumatic brain injury (MTBI) with working memory functional magnetic resonance (MR) imaging. MATERIALS AND METHODS: Research ethics committee approval and patient written informed consent were obtained. Working memory brain activation patterns were assessed with functional MR imaging in 30 patients (15 consecutive men and 15 consecutive women) with MTBI and 30 control subjects (15 consecutive men and 15 consecutive women). Two imaging studies were performed in patients: the initial study, which was performed within 1 month after the injury, and a follow-up study, which was performed 6 weeks after the first study. For each participant, digit span and continuous performance testing were performed before functional MR imaging. Clinical data were analyzed by using Kruskal-Wallis, Mann-Whitney U, Wilcoxon signed rank, and Fisher exact tests. Within- and between-group differences of functional MR imaging data were analyzed with one- and two-sample t tests, respectively. RESULTS: Among female participants, the total digit span score was lower in the MTBI group than in the control group (P = .044). In initial working memory functional MR imaging studies, hyperactivation was found in the male MTBI group and hypoactivation was found in the female MTBI group compared with control male and female groups, respectively. At the 6-week follow-up study, the female MTBI group showed persistent hypoactivation, whereas the male MTBI group showed a regression of hyperactivation at visual comparison of activation maps. The male MTBI group was also found to have a higher initial ß value than the male control group (P = .040), and there was no significant difference between the male MTBI group and the male control group (P = .221) at follow-up evaluation, which was comparable to findings on activation maps. In the female MTBI group, average ß values at both initial and follow-up studies were lower compared with those in the female control group but were not statistically significant (P = .663 and P = .191, respectively). CONCLUSION: Female patients with MTBI had lower digit span scores than did female control subjects, and functional MR imaging depicted sex differences in working memory functional activation; hypoactivation with nonrecovery of activation change at follow-up studies may suggest a worse working memory outcome in female patients with MTBI.

May-Thurner syndrome: correlation between digital subtraction and computed tomography venography.

BACKGROUND/PURPOSE: Digital subtraction venography (DSV) and computed tomography venography (CTV) are both recommended for diagnosing May-Thurner syndrome. The literature contains little information on the correlation between these imaging tools. We performed a retrospective case-series study to investigate this correlation. METHODS: From August 2009 to August 2010, 42 patients with May-Thurner syndrome (34 women, 8 men; mean age: 52.8 ± 13.5 years) received DSV followed by CTV. The DSV was used to evaluate the degree of venous reflux, reflux start-up time, and flow time. By CTV, the ratio of cross-sectional area and the ratio of diameter between the narrowest region to that of the caudal part of the left common iliac vein were calculated. The correlation between these variables for DSV versus CTV was calculated using Spearman's rank correlation coefficients. RESULTS: In DSV evaluation of the extent of reflux, 19.0% of cases were classified as Grade 0, 11.9% as Grade I, 28.6% as Grade II, and 40.5% as Grade III. The mean ± standard deviation flow times for these groups were 2.00 ± 0.38 seconds, 1.75 ± 0.29 seconds, 1.67 ± 0.72 seconds, and 1.81 ± 0.68 seconds, the mean time for total patients was 1.76 ± 0.78 seconds. The reflux start-up times for Grades I-III were 2.00 ± 1.00 seconds, 1.80 ± 1.23 seconds, and 1.40 ± 0.49 seconds, and the mean time was 1.6 ± 0.8 seconds. In CTV, the mean area ratio and diameter ratio were 0.78 ± 0.22 (range, 0.22-1.27) and 0.75 ± 0.24 (range, 0.33-1.25). The reflux start-up time showed a positive correlation with the cross-sectional area ratio (r = 0.518; p = 0.002) and diameter ratio (r = 0.413; p = 0.019). CONCLUSION: The cross-sectional area ratio and diameter ratio in CTV correlate with the reflux start-up time in DSV. For May-Thurner syndrome, both CTV and DSV provide essential information for diagnosis and evaluation of the disease. The positive correlation between anatomical and hemodynamic properties corresponds with the underlying pathophysiology.

Endovascular Stenting of an Extracranial-Intracranial Bypass Stenosis: A Technical Note.

The use of an extracranial-intracranial (EC-IC) bypass has been a choice to improve the safety of parent vessel occlusion during the management of aneurysm. However, the prognosis and subsequent patency of bypass graft are variable and have seldom been managed by endovascular treatment. A 38-year-old gentleman presented to our hospital with intermittent headache. Subarachnoid hemorrhage caused by an internal carotid artery aneurysm was disclosed on the subsequent examination. He received an EC-IC bypass later. However, graft stenosis was found during follow-up. To solve the stenosis, an endovascular stent was inserted by us. There is seldom report of endovascular treatment of the graft. Here we share our experience under such circumstances.

Susceptibility-weighted MRI in mild traumatic brain injury.

OBJECTIVE: To compare the frequency of microbleeds identified by susceptibility-weighted MRI (SWMRI) in patients with mild traumatic brain injury (mTBI) and normal controls, and correlate these findings with neuropsychological tests. METHODS: Research ethics committee approval and patient written informed consents were obtained. One hundred eleven patients with mTBI without parenchymal hemorrhage on CT and conventional MRI received SWMRI as well as a digit span and continuous performance test. One hundred eleven healthy volunteers without history of traumatic brain injury were enrolled as the control group and received conventional MRI with additional SWMRI study. We analyzed the number and location of microbleeds in both groups. RESULTS: Twenty-six patients with mTBI and 12 control subjects presented microbleeds on SWMRI (p = 0.0197). Sixty microbleeds were found in 26 patients with mTBI and 15 microbleeds in 12 control subjects. The mTBI group showed notably more microbleeds in the cortex/subcortical region (52 microbleeds, 86.7%, vs 3 microbleeds, 20%; p < 0.0001). Conversely, the control group showed more microbleeds in the central brain (9 microbleeds, 60%, vs 3 microbleeds, 5%; p < 0.0001). There was no statistical difference in number of microbleeds in the cerebellum and brainstem (p = 0.2598 and p = 0.4932, respectively). Patients with mTBI who had detected microbleeds had lower digit span scores than the patients with negative SWMRI findings (p = 0.017). CONCLUSION: Presence of mTBI-related microbleeds showed a neuropsychological defect on short-term memory function, indicating that the presence of microbleeds could be a possible severity biomarker for mTBI. Addition of the SWMRI technique to the MRI protocol for patients with mTBI is recommended.