Occurrence of Post-Acute Recanalization and Collateral Formation in Patients with Cerebral Venous and Sinus Thrombosis. A Serial Venographic Study

The underlying mechanism for symptomatic recovery in patients with cerebral venous and sinus thrombosis (CVST) is not clear, although post-acute recanalization and collateral formation have been proposed as possible mechanisms. To identify the occurrence of recanalization and collateral formation among survivors of CVST and explore its association with symptomatic recovery.

We identified all the patients admitted with CVST over a 5-year period and who underwent initial magnetic resonance (MR) or computed tomographic (CT) venography and a follow-up CT or MR venography between 3 and 12 months after onset. All the images were reviewed by a single observer using the classification for recanalization proposed by Qureshi grade I—partial recanalization of one or more occluded dural sinus with improved flow or visualization of branches; grade II—complete recanalization of one sinus but persistent occlusion of the other sinuses [A—no residual flow, B—non occlusive flow]; grade III—complete recanalization and for collateral formation (grade I—collaterals bypass occluded segment of dural venous sinus but connect within the same sinus; grade II—collaterals bypass occluded segment but connect with a different sinus; grade III—collaterals bypass the occluded segment and connect with different circulation).

A total of 39 patients with CVST (mean age 34.82 [±17.1 SD]; 19 were men) had an initial and follow-up venographic study performed. Of these, 21 patients underwent serial venographic imaging using the same modality allowing a direct comparison. Of the 17 patients who had recanalization during follow-up, 10 patients had grade I recanalization, 7 had grade III recanalization, and 4 had no recanalization. Collateral formation was seen in 8 patients: grade I in 3 patients, grade II in 1 patient, and grade III in 4 patients. The proportion of patients with persistent headaches appeared higher in those with no or partial recanalization than with complete recanalization (5 of 14 patients vs. 0 of 7 patients) and in patients with no collaterals than patients with collaterals (4 out of 13 vs. 1 out of 8). None of the patients experienced any recurrence or new symptoms.

Complete or partial recanalization and collateral formation are seen in a prominent proportion of patients with CVST in the months following initial diagnosis. Further studies need to identify the temporal course and clinical significance of venographic recanalization and collateral formation, and factors influencing venographic changes.