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The Doppler CO2 test to exclude patients not in need of extracranial/intracranial bypass surgery.
  1. B Widder
  1. Department of Neurology, University of Ulm, Federal Republic of Germany.


    In patients with an internal carotid artery (ICA) occlusion who suffer from ipsilateral transient ischaemic attacks or minor stroke extra/intracranial (EC/IC) bypass surgery may be useful only where there is insufficient collateral supply. The transcranial Doppler CO2 test offers a simple method of investigating the residual autoregulatory capacity which gives quantitative information about the efficiency of the collaterals. In 155 patients with 162 ICA occlusions there was a significant correlation between a markedly decreased or exhausted autoregulatory capacity and a recent ipsilateral ischaemic event (p less than 0.001). The Doppler CO2 test may enable the exclusion of patients not in need of EC/IC bypass surgery. In the reported series this affected more than 80% of all ICA occlusions.

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