Authors: Robert H. Andres, Raphael Guzman, Alain Barth, Marwan El-Koussy, Arjun V. Pendharkar and Gerhard Schroth
Abstract: Arteriovenous malformations (AVMs), arteriovenous fistulas (AVFs), and cavernomas are rare vascular lesions of the spinal cord that are difficult to diagnose and can lead to considerable morbidity if left untreated. According to the most widely used classification, spinal arteriovenous lesions are divided in 4 major categories based on their anatomical and pathophysiological features: Type I, dural AVFs; Type II, glomus or intramedullary AVMs; Type III, juvenile or combined intra- and extradural AVMs; and Type IV, intradural perimedullary AVMs. Spinal cavernomas constitute an additional entity of almost exclusively intramedullary lesions. Type I AVFs constitute the vast majority of spinal vascular malformations and usually become symptomatic by slowly progressive congestive myelopathy. Hemorrhage due to these lesions is considerably rare. In contrast, Type II-IV AVMs and cavernomas can cause venous congestion, space-occupying effects, and subarachnoid or intramedullary hemorrhage. Due to the variable and nonspecific presentation of these lesions, the threshold for performing diagnostic workup should be low. Neuroradiological evaluation should include magnetic resonance imaging of the whole spine and selective spinal catheter angiography to confirm diagnosis. Available treatment options depend on the structural and hemodynamic properties of each lesion, as well as the relationship to the spinal cord and vasculature. For Type I AVFs, treatment usually consists of surgical or endovascular occlusion of the draining vein at the fistulous point. Type II AVMs may be treated by surgery or embolization, and in most cases, Type III and IV AVMs are treated by endovascular therapy. If complete occlusion of an AVM or AVF is achieved, the majority of cases will result in good clinical outcome. Symptomatic cavernomas should be totally resected if possible. Complete resection improves neurological recovery in most patients and eliminates the risk of recurrent hemorrhage. The heterogeneous presentation and clinical nature of spinal vascular malformations presents special diagnostic and therapeutic challenges. As a result, the optimal treatment strategy for these lesions should be determined for each patient on an individual basis by an experienced interdisciplinary neurovascular team.