Safety of Ablation of the Sigmoid and Transverse Sinuses: An Experimental Study

Abstract

Various techniques and approaches have been developed to minimize invasion in skull base surgery. If the sigmoid and transverse sinuses could be divided safely, surgeons could have better surgical access without much retraction of the brain. However, it is currently believed that these sinuses contain important routes of venous drainage from the brain and that, if they are sacrificed, severe brain swelling would follow.Recently, surgical techniques were reported by which the sigmoid and transverse sinuses could be divided. [1][2][3] The authors found it safe to divide the sigmoid sinus and proposed that the divided transverse sinus be closed on completion of the operation. Generally, however, it is still considered risky to ablate these sinuses to provide access to skull base and brain.We performed the present study to establish the safety of sacrificing these sinuses experimentally in monkeys, since it is well known that the venous drainage of the monkey's brain is quite similar to that in humans. The purpose of the present study was to measure the effect of sacrificing the sigmoid and transverse sinuses on sinus pressure, regional cerebral blood flow (rCBF), and cortical motor evoked potentials(MEP). MATERIALS AND METHODSJapanese monkeys (Macacafascata) weighing 5 to 6 kg were used for the experiments described. After induction with ketamine and atropine at doses of 5 and 0.2 mg/ kg, respectively, general anesthesia was established with thiamylal (10 mg/kg) given intravenously, and an endotracheal tube was inserted. Serial blood gas measurements were taken throughout the surgery and partial arterial carbon dioxide pressure was kept within the normal physiologic range (35 to 40 mmHg) by giving room air or oxygen (2 ml/min). Blood pressure (femoral artery, A line) was also maintained around the level of 90 to 105 mmHg. While in the prone position, suboccipital craniectomy was performed after a linear skin incision was made. The craniectomy extended across the transverse and sigmoid sinuses. A parietal craniectomy was also performed and a part of the dura was opened to measure MEP and rCBF at the prefrontal motor cortex. This craniectomy also allowed inspection of the brain surface for venous congestion. In two monkeys in which bilateral transverse sinuses are occluded and the pressure was measured in the

Enlarged Vertebral Venous Plexus Alleviated Intracranial Hypertension-Related Symptoms in Patients with Bilateral Transverse Sinus Stenosis

“…This finding was supported by Bono et al [22]. This lack of association may be due to the compensatory effect of vein of Labbe and occipital sinus [23, 24]. EVVP is negatively correlated with ICP after adjusting for the severity of BTSS.…”

Occlusion of the sigmoid sinus after surgery via the presigmoidal—transpetrosal approach

“…15,17,20,26,29,30,34,37 By preserving the sigmoid sinus without transecting it, the complication of venous circulation failure due to postoperative occlusion of the sigmoid sinus can likely be avoided. 1,29,30 Intra-or postoperative occlusion of the sigmoid sinus can occur for various reasons, such as mechanical damage or heat injury caused by air drilling during exposure of the sigmoid sinus, subsequent compression with the spatula, or drying caused by exposure to air.…”

Clinical course of idiopathic intracranial hypertension with transverse sinus stenosis

“…Blood flow through enlarged dural veins in superior sagittal sinus occlusion has been demonstrated, and may represent one collateral path. 24 Two additional paths include the vein of Labbe 25 (a cortical vein that drains the lateral surface of the hemispheres) and the occipital sinus 26 (draining directly from the torcular). Both of these structures can, albeit with variation, drain into the sigmoid sinus, bypassing the distal TS where the majority of stenoses in patients with IIH occur.…”