The role of diagnostic imaging techniques for detection of extracranial venous system abnormalities associated with central nervous system disorders

The extracranial venous system is complex and variable. In the last decade, it has been repeatedly shown that the presence and severity of jugular vein reflux is associated with a number of central nervous system (CNS) disorders such as transient global amnesia, transient monocular blindness, cough headache, primary exertional headache, and more recently Alzheimer’s disease and aging. A newly proposed vascular condition, named chronic cerebrospinal venous insufficiency (CCSVI), has triggered recently intense interest in better understanding the role of extracranial venous abnormalities and their developmental variants. Their relationship to intracranial CNS pathology, especially in patients with multiple sclerosis (MS), is poorly understood at this time. So far there is no established invasive or noninvasive diagnostic imaging modality that can serve as a “gold standard” for the detection of these venous abnormalities/developmental variants. The use of noninvasive diagnostic imaging techniques such as Doppler sonography (DS) remains controversial; however, consensus guidelines and standardized protocols are emerging. The use of magnetic resonance venography (MRV) and phase-contrast imaging is gaining an increasing interest as an alternative noninvasive diagnostic approach. Further, catheter venography (CV) and intravascular ultrasound (IVUS) are becoming important diagnostic tools for confirming the presence and severity of extracranial venous pathology. Most likely, a multimodal imaging approach will ultimately be the most comprehensive means for screening, diagnostic, as well as monitoring purposes. Further research is needed to determine the spectrum and prevalence of these extracranial venous abnormalities/developmental variants and to compare the imaging findings with pathological examinations.