Superficial middle cerebral vein connection to the cavernous sinus is not infrequent in brain arteriovenous malformations: an argument against their congenital origin?

Temporal lobe tumors modify local venous drainage

OBJECTIVE

Superficial Middle Cerebral Vein (SMCV) is an anastomotic vein frequently exposed during surgery. Changes in the pattern of cerebral venous outflow can occur in many pathological settings. We explored the hypothesis that the growth of an intracranial tumor could determine alterations in the venous outflow. We analyzed SMCV anatomical variants in patients undergoing surgery for intracranial tumors; we furthermore focused on association with histology.

METHODS

We retrospectively collected data of 120 patients undergoing surgery, 60 presenting intracranial tumor and 60 presenting cerebral aneurysms (control group). Tumor series was divided into "Low Growth-Rate tumors" (WHO grade I and II) and "High Growth-Rate tumors" (WHO grade III and IV). Anatomical variants of SMCV were analyzed on intraoperative videos and then classified as Type 1 (normotrophic), 2 A (hypotrophic) and Type 2B (absent/atrophic). We furthermore defined as Type 2 any alteration of the SMCV (2 A+2B) encountered. Relationships among SMCV types and both populations were analyzed using the chi-squared test; values of p < 0.05 were considered statistically significant.

RESULTS

We found a positive correlation between the presence of a primary brain tumor and Type 2B SMCV (PC.004, p < 0.05) and Type 2 SMCV (PC.000, p < 0.05). Specifically, we found a strong correlation between the absence of SMCV (Type 2B) and both tumors subgroups. Thus, the growth of a primary brain tumor seems to affect the cerebral local outflow.

CONCLUSIONS

Primary brain tumors seem to alter local venous network of SMCV. Clinical and oncological implications remain subject of further investigation.

Anatomical Variations of Brain Venous Sinuses in Patients with Arteriovenous Malformations: Incidental Finding or Causative Factor?

OBJECTIVE

Acquired anomalies of the dural venous sinuses (DVS) have been correlated extensively with the development of dural arteriovenous fistulas (DAVFs). Despite the known similarities of DAVFs' pathogenesis with that of arteriovenous malformations (AVMs), the relationship of venous sinuses anomalies with AVMs scarcely has been studied. We aimed to investigate whether patients with AVM show a greater prevalence of congenital DVS anomalies. We hypothesized that these congenital anomalies trigger AVM development during early childhood just as acquired DVS anomalies trigger DAVFs formation during adulthood.

METHODS

Angiographic anomalies of the brain venous sinuses were studied in a cohort of 45 consecutive patients with AVM and compared with the angiographic; venous sinus anomalies of a control group formed by a second consecutive; series of 45 patients with subarachnoid hemorrhage.

RESULTS

Congenital anomalies of any DVS were more frequent in patients with AVM than in the control group (49.8% vs. 22.2%; P = 0.015). Congenital abnormalities of the superior sagittal sinus not only were more frequent in patients with AVM (27% vs. 6.7%; P = 0.021) but seemed also related to the AVM location: in 5 of the 6 AVM cases with unilateral superior sagittal sinus aplasia, the AVM was ipsilateral to the venous anomaly.

CONCLUSIONS

Patients with AVM have a greater likelihood of congenital anomalies of any DVS. These anomalies seem to be related also to the AVM location. These findings suggest that congenital anomalies of DVS may be related to the development of AVMs.