Post-operative Sinus Thrombosis in the Setting of Skull Base and Parasagittal Surgery

Background and Purpose: Cerebral venous sinus thrombosis (CVST) is a known complication of skull base and parasagittal surgeries. While a majority of these cases are asymptomatic, severe sinus thrombosis can have devastating consequences such as hemorrhage or infarct. The objective of this study was to prospectively evaluate the true incidence and risk factors associated with post-operative CVST, and comment on management strategies.

Materials and Methods: A prospective study of 69 patients who underwent either a retrosigmoid, translabyrinthine or suboccipital approach for posterior fossa tumors or a supratentorial craniotomy for a parasagittal/falcine tumor was performed. All patients obtained pre- and post-operative MR venography studies to evaluate the patency of the major dural sinuses. Various demographic, clinical and operative data was collected. Treatment decisions for thromboses were made according to the attending surgeon’s preference. Statistical analysis was performed to identify incidence and risk factors.

Results: Among 69 patients, 22 (31.9%) were found to have filling defects on post-operative MR venography. Of these 22 cases, 19 were non-occlusive and all patients were asymptomatic. No risk factors were statistically correlated with thrombosis including BMI (p = 0.652), hypercoagulable state (p = 0.348), surgical approach (p = 0.784), length of surgery (p = 0.917), intraoperative fluid balance (p = 0.931), intraoperative use of mannitol (p = 0.084), tumor volume (p = 0.177), tumor type (acoustic neuroma versus meningioma; p = 0.717), tumor invasion into the sinus (p = 0.253) and extent of resection (p = 0.962). All patients were treated conservatively, 23/24 with observation only and 1/22 with intravenous fluids. There were no instances of venous infarcts, hemorrhages or associated neurologic deficit, and one case of a septic thrombus. Six out of 22 patients (27%) in the thrombosis group had a CSF leak during the post-operative period compared with 2/47 (4.2%) in the non-thrombosis group (p = 0.01). No patients required a shunt to treat the CSF leak.

Conclusions: This prospective study shows that the radiographic incidence of post-operative CVST is higher than what has been previously reported in retrospective studies. In the absence of symptoms, these generally non-occlusive filling defects can be treated conservatively with observation or intravenous fluids. While no risk factors were identified, there may be an association between post-operative CVST and CSF leaks.