With increasing use of high field scanners and high resolution imaging protocols such as susceptibility-weighted imaging that can be used to visualize fine venous structures, understanding of the structure of fine venous anatomy has become important. Deep medullary veins drain into subependymal veins with four convergence zones and show parallel distribution patterns adjacent to the body or inferior horn and a radial pattern in the frontal horn or trigon of the lateral ventricle. Some disorders are related to deep medullary veins.
Although many studies on vessel anatomy have been performed using dissection or angiographic techniques, and much knowledge and information accumulated prior to the CT and MRI era, radiologists and other physicians currently tend to not examine fine vessel anatomy that cannot be visualized on conventional CT or MRI. However, with increased use of 3-T scanners and high resolution imaging protocols such as susceptibility-weighted imaging (SWI) that can be used to visualize fine venous structures, understanding of the structure of fine venous anatomy has become important, even in daily clinical diagnosis.
In this talk, fine structure of the medullary vein will be discussed. Veins of the cerebral hemisphere consist of pial veins and parenchymal veins. We will discuss the superficial and deep draining medullary veins. Superficial medullary veins include intracortical veins, subcortical veins, and superficial medullary veins. Deep medullary veins consist of deep medullary veins and subependymal veins including the longitudinal caudate veins of Schlesinger. Deep medullary veins drain into subependymal veins with four convergence zones and show a parallel distribution pattern adjacent to the body or inferior horn and a radial pattern in the frontal horn or trigon of the lateral ventricle.
The mechanism or cause of the above mentioned convergence pattern of the medullary veins is not clear. However, when the morphology of the vessel structure and white matter fiber tract is compared and correlated, some hypotheses emerge. Huang and Okudera et al. speculated that the formation of convergence zones correlates with the rapid changes in the course, shape, size, and number of the converging medullary veins caused by the fast-growing crossing nerve fiber tracts, including projection, commissural, and association fiber tracts (1,2).
Some disorders are related to deep medullary veins. In this talk, disorders, following disorders will also be discussed 1) hemorrhagic disorders related to the medullary veins (diffuse vascular injury due to high energy trauma, deep medullary vein engorgement/thrombosis in neonates), 2) inflammatory changes that spread along the medullary veins, and 3) anomalies of the medullary veins(3).
1. Huang YP, Okudera T, Fukusumi A, Maehara F, Stollman AL, Mosesson R, et al. Venous architecture of cerebral hemispheric white matter and comments on pathogenesis of medullary venous and other cerebral vascular malformations. Mt Sinai J Med 1997;64(3):197-206.
2. Okudera T, Huang YP, Fukusumi A, Nakamura Y, Hatazawa J, Uemura K. Micro-angiographical studies of the medullary venous system of the cerebral hemisphere. Neuropathology 1999;19(1):93-111.
3. Taoka T, Fukusumi A, Miyasaka T, Kawai H, Nakane T, Kichikawa K, et al. Structure of the Medullary Veins of the Cerebral Hemisphere and Related Disorders. Radiographics 2017;37(1):281-97.