Transcranial Doppler sonography as a prognostic parameter in unilateral occlusion of the internal carotid artery - A prospective follow-up study

Transcranial Doppler-Sonography (TCD) is a reliable tool for the evaluation of the haemodynamic situation distal of an occlusion of the internal carotid artery (ICA). Our aim was to perform a prospective follow-up study over several years with a preexisting record of TCD parameters. Thirty-four patients were included. All patients fulfilled the following criteria: 1. Angiographically confirmed occlusion of the ICA, 2. No evidence of intracranial stenosis or occlusion. 3. Transtemporal bone window for transcranial Doppler signals. 4. Regular participation in follow-up examinations in 6 months intervalls. Mean duration of follow-up was 41 months (Standard deviation: 6.5 months). At the beginning of our study a TCD was performed on the ipsilateral and contralateral side of the ICA occlusion to examine the following parameters: Systolic and diastolic flow velocities, pulsatility index and difference of TCD parameters in the ipsilateral and contralateral middle cerebral artery (MCA). Occurrence of TIA or stroke was recorded. Eleven patients became symptomatic. Asymptomatic patients had a significantly higher pulsatility in the ipsilateral MCA (p < 0.02) indicating that this parameter is sensitive to haemodynamic effects of ICA obstructions. In addition the number of cerebral collaterals was significantly higher in patients with a higher pulsatility in the ipsilateral MCA (p < 0.05). A high pulsatility index of the ipsilateral MCA distal to an occlusion of the ICA and a higher number of cerebral collaterals in TCD indicate a better prognosis.