Dilated perivascular spaces: hallmarks of mild traumatic brain injury

BACKGROUND AND PURPOSE: Recent animal and human studies have shown an increased frequency of enlarged, high-convexity Virchow-Robin spaces (VRS) in several neurologic diseases, suggesting their role as neuroradiologic markers of inflammatory changes. The aim of this study was to determine the prevalence of high-convexity dilated VRS in mild traumatic brain injury (TBI). METHODS: T2-weighted, T1-weighted, fluid-attenuated inversion recovery, and T2*-weighted gradient-echo brain MR images were acquired in 24 patients with TBI (10 women, 14 men; mean age, 33.6; range, 18.1-50.8 years) and 17 age- and sex-matched healthy control subjects (nine women, eight men; mean age, 32.8; range, 18.4-47.8 years). The mean interval after TBI was 3.6 days (range, 1-9 days) in 15 patients and 3.7 years (range, 0.6-13.4 years) in nine patients. Axial T2-weighted images were used to identify dilated VRS and to measure CSF volume; T1-weighted images were used to measure brain volume. Dilated VRS were identified as punctuate areas with CSF-like signal intensity in the high-convexity white matter. RESULTS: Mean (+/- standard deviation) number of VRS was significantly higher in patients (7.1 +/- 4.6) than in controls (3.0 +/- 3.0, P = 0.002) [corrected] In controls, VRS were associated with age (R = 0.69, P < .001) whereas in patients, they neither correlated with brain and CSF volumes nor with age and the elapsed time from injury. CONCLUSION: Our results suggest that the increased number of dilated VRS is a radiologic marker of mild head injury that is readily detectable on T2-weighted images. Because their number does not vary with time from injury, VRS probably reflect early and permanent brain changes.     

Morphologic characteristics of varicose veins: possible role of metalloproteinases

BACKGROUND: Although varicose veins are a common cause of morbidity, etiologic factors predisposing to dilatation, elongation, and tortuosity of the saphenous vein and its tributaries are poorly understood. We compared histologic features of normal and varicose saphenous veins and investigated the role of enzyme or inhibitor imbalance in development of varicosities. METHODS: Eight normal and 10 varicose (C(2,3)E(P,S)A(S)P(R,O)) vein segments were used for this analysis. Matrix metalloproteinase (MMP) expression and activity were analyzed with Western blotting and zymography. Venous architecture and protein localization were determined with histology and immunohistochemistry. RESULTS: Western blot analysis demonstrated the presence of MMP- 1, MMP-2, MMP-9, and MMP-12, as well as small quantities of tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2 in protein isolates from normal and varicose veins. Both vein types demonstrated MMP-2, MMP-9, and MMP-12 activity by gelatin zymography, although varicose vein expressed less MMP-9 activity than normal vein did. Compared with normal veins, changes in varicose veins were not uniformly distributed along the circumference; areas of intimal thickening were often interspersed with focal areas of dilatation. Fragmentation of elastic lamellae and loss of circular and longitudinal muscle fibers were evident in the varicosities. Focal aggregates of macrophages were detected within the media and adventitia of both normal and varicose veins. MMP-1 and MMP-9 were expressed in both types of vein segments; however, their immunohistochemical localization was distinctly different. In normal vein, endothelial cells, occasional smooth muscle cells (SMC), and adventitial microvessels expressed MMP-1, whereas its expression was localized to fibroblasts, SMC, and endothelial cells throughout involved portions of varicose veins. MMP-9 was localized to endothelial cells, medial SMC, and adventitial microvessels in both normal and varicose veins, although varicose veins demonstrated increased medial smooth muscle cell staining. MMP-12 was found in SMC and fibroblasts in both normal and varicose veins. Neither TIMP-1 nor TIMP-2 were detected with immunohistochemistry in any specimens examined. CONCLUSIONS: There are distinct differences in the structural architecture and localization of MMP expression in normal and varicose veins. Although the changes observed are not sufficiently definitive to enable a causal relationship, they do suggest a possible mechanism for the alterations in matrix composition observed between normal and varicose veins.     

Nonsurgical repositioning of central venous catheters

Long-term central venous catheters are placed for total parenteral nutrition and/or chemotherapy. These catheters are placed surgically and fixed to the subcutaneous tissues. Complications include infection, venous thrombosis, and mechanical problems. The authors developed a method to percutaneously reposition displaced central venous catheters. The procedure is performed with fluoroscopy and modified angiographic techniques. Fifteen patients underwent a total of 17 procedures. The initial success rate was 76%; the final success rate was 88%. Many central venous catheters can be salvaged with this low-morbidity procedure, which negates the need for surgical intervention.