What could these mri results signify: "asymmetry of the dominant venous sinuses on the right side. long and tapered stenosis of the left transverse sinus. venous anastomosis between the right sinus and left internal jugular vein." apart from iih?

This has to be interpreted in conjunction with the symptoms and reason for ordering it . your MD should explain it

If you suffer from Idiopathic Increased Intracranial Pressure, (Pseudotumor), one potential cause could be venous sinus thrombosis. However, your posted description is more in keeping with a congenital anomaly. This needs clinical correlation, and the proper approach is to see your physician and discuss the potential correlations and the next appropriate steps.