Vertebral artery dissection is one of the common causes of posterior territory stroke in young. Recognition of the dissection depends on choosing the ideal imaging modality. MR with 3D TOF MRA is usually the initial imaging modality for stroke in young. Care must be taken to assess for T1 shortening along the course of the vertebral artery walls, which should not be mistaken for normal flow (as flow signal and signal of meth-hemoglobin is identical on TOF). Once such an abnormality is identified, it is essential to confirm these findings with a fat Sat T1W sequence in the affected segment of the vertebral artery, followed by contrast enhanced MRA.
This was especially essential in our case, in view of the fact that the dissection had not caused complete occlusion of the artery and small patent true lumen was seen even beyond the segment of dissection.
The lack of flow in one vertebral artery with mural thickening are other signs of vertebral artery dissection.
CT angiography may not be helpful in cases like ours, in view of the fact that the hematoma was only segmental, subacute (hence may be isodense and missed) and did not cause complete obstruction.
The study of vertebral arteries is challenging, especially when dissection is suspected and appropriately designed examinations are needed. A multiparametric approach, with T1WI, T2WI, and TOF MRA followed by CE-MRA may be useful to identify the vessel pathology and differentiate hematomas and venous structures (1).
This case was contributed by Dr. Anisha Sawkar, Radiologist at St Johns Hospital.