Intracranial haemodynamics in Takayasu's arteritis.

The cerebral circulation was assessed in two cases of Takayasu's arteritis by angiography of the aortic arch, cerebral blood flow single photon emission computed tomography (SPECT) and transcranial Doppler sonography (TCD). In both cases, disease of the major brachiocephalic arteries affected flow in the vertebrobasilar system and circle of Willis. Basilar artery flow was permanently reversed in one case, with vertebrovertebral shunting and subclavian steal. In the other case, focally reduced cerebral hemisphere flow resulted from watershed between vascular territories. The complex collateral and haemodynamic changes produced by multi-vessel involvement in Takayasu's arteritis suggest that therapeutic approaches should be based on assessment of end-organ perfusion rather than on structural angiographic changes.