What is the risk of venous infarction to intra-operative sacrifice of either the superficial or deep cerebral bridging veins?

Abstract

Dear Editor: In the article entitled “The intracranial bridging veins: a comprehensive review of their history, anatomy, histology, pathology, and neurosurgical implications” by Mortazavi et al [1], the authors state in the section entitled Surgical significance of the bridging veins, “Furthermore, identification of the bridging veins during surgery makes the neurosurgeon aware of avoiding damage to them in order to prevent venous infarction secondary to iatrogenic occlusion of these veins.” Although this is a concept that is widely accepted, one could question what evidence exists to support this conclusion. The most direct route to many midline cerebral lesions is often barred by the presence of superficial or deep bridging veins. Because of the perceived consequence of surgically occluding and dividing these veins, imaging studies are frequently obtained to map a corridor that may be less direct and/or restricted so as to avoid these veins in order to reach the desired destination. This can result in a less than optimal exposure and ability to achieve the ideal outcome be it greater or complete tumor resection or reduced collateral involvement of structures adjacent to the target location. Conventional wisdom predicts venous infarction is likely to occur with obstruction to either the superficial or deep bridging veins [2]. Extensive connections exist between the superficial and deep venous systems with a significant degree of overlap and bidirectional flow as the cerebral veins have no valves [3]. The extensive anastomotic nature of the cerebral venous system allows venous drainage to be altered as needed through the numerous collateral pathways. We have reported on our own experience in a pediatric population of occluding one or more middle-third superior sagittal sinus cortical bridging veins in 63 patients as the initial intracranial step in a transcallosal approach to deep midline tumors without a single incidence of venous infarction [4]. This study was followed by a second publication investigating a retrocallosal approach to pineal lesions wherein superficial bridging veins were sacrificed in seven patients and deep bridging veins (basal vein of Rosenthal, internal cerebral vein, and precentral cerebellar vein) in another three patients with no evidence of venous infarction [5]. In a third publication, we reviewed the clinical and experimental literature regarding the effects of sacrificing the deep cerebral veins and did not find evidence of the dire consequences of venous infarction that conventional wisdom espouses [6]. It is highly suspected that the sequelae attributed to occluding the superficial and deep bridging cerebral veins result from brain retraction, especially against gravity (Fig. 1) [7] and can be avoided by positioning the patient and using an approach wherein gravity is an ally and not an enemy. Using the most direct approach to the region of interest without regard to the location of the bridging cerebral veins is of significant advantage. J. G. McComb Division of Neurosurgery, Children’s Hospital of Los Angeles, 1300 N. Vermont Ave, Doctor’s Tower, Suite 1006, Los Angeles, CA 90027, USA