Comparison of transcranial Doppler with DSA in vertebrobasilar ischaemia.

To determine the role of transcranial doppler (TCD) in the evaluation of the vertebrobasilar circulation, we compared the results of TCD with intraarterial digital subtraction angiography (DSA) in 20 patients with vertebrobasilar ischaemia (VBI). TCD had a sensitivity of 87%, a specificity of 80%, a positive predictive value of 93% and a negative predictive value of 67%. It was also able to give functional data when combined with arteriography and correctly identified the main pathology in 92% of those with abnormal TCD and angiogram. The 2 patients with false negative TCD had vertebral artery occlusion, which may be missed because of the signal from adjacent arteries. TCD may be a useful screening method in patients with VBI for the detection of large vessel occlusive disease of the intracranial vertebrobasilar system. It is important to remember that proximal vertebral artery stenoses will be missed by TCD.