The cranio spinal epidural spaces were categorized into three different compartments ventral, dorsal and lateral. Each compartment has its specific drainage role in relation to the embryologic deveropment of the venous system of the central nervous system (CNS) and the surrounding bony structures. The ventral epidural space drains structures derived from the notochord and adjacent sclerotomes, The dorsal epidural group is related to the drainage of the spinous processes at the spinal level and

more »

... o the vault and calvarium cranially The lateral epidural group colle ¢ ts the emissary bridging veins of the pial venous system of the spinal cord ancl brain. The dural arteriovenous shunts (DAVS) developing in these spaces predictably drain either in the subarachnoid veins or in the epidural-paraspinal collectors according to the epidural compartment involved, Additional com morbiditM like epidural venous thrombosis or high fiow characteristics of the DAVS, will be responsible for changes in the draining pattern of otherwise anticipated spinofugal or craniofugal drainage, This embryologically based classification establishes hornoiogies between spinal and cranial epidural spaces, thus allowing epidemiological and clinical comparison including spinal and cranial DAVSs, Keywords : cranial dural arteriovenous epidural veins Jpn J Neurosurg fistula,spinal dural arteriovenous fistula, classification, (Tbkyo) 17:356-361, 2008 lntroduction Dural arteriovenous shunts or fistulas (DAVS or DAYF) are abroacl group of diseases that share involvement of the epidural space and adiacent dura mater and bony structures. Different classifications have been proposed for these lesionsO-'3), however it is generally accepted that the presence or absence of cortical venous reflux angiographic finding constitutes the majer and only clinical consideration regarding the natural history and, therefore, the therapeutic strategies for these lesions. The purpose of this new classification is an attempt to ground the gender dominance or age at presentation seen in some localization and to link spinal and cranial lesions. Three observations of the venous development of the brain and spinal cord and adjacent bony structures, contribute to the generation of the new elassification : 'The venous system of the notochord and corresponding selerotome, extends from the basi-sphenoid (cavern-