MULTIMODAL CAROTID TEST OCCLUSION FOR EVA LUATION OF STROKE RISK IN THERAPEUTIC OCCLUSION OF THE INTERNAL CAROTID-ARTERY

In patients with head and neck carcinoma and extensive cervical metast asis, the topographic and functional relationship of the tumor to the carotid artery is highly important. In case of suspected carotid infil tration, the possibility of a carotid resection or a prosthetic replac ement has to be considered preoperatively. Treatment of cavernous caro tid aneurysms may also require sacrificing the internal carotid artery (ICA). An interdisciplinary test occlusion of the ICA was performed t o assess cerebral collateral circulation prior to permanent carotid oc clusion. Materials and Methods: Fifty-two patients with cervical tumor s (n = 45) or inoperable aneurysms (n = 7) were examined. The endovasc ular balloon test occlusion (BTO) of the ICA was combined with monitor ing of the neurological status, cardiovascular status (EKG, blood pres sure), cortical function (EEC), and single photon emission CT (SPECT) imaging of the regional cerebral blood flow (rCBF) with (99m)Technetiu m-HMPAO. In the last 24 patients, transcranial Doppler sonography (TCD ) of the ipsilateral middle cerebral artery (MCA) was added for direct hemodynamic monitoring during BTO. In order to improve the diagnostic value of the test results a nd to si mu late hemodynamic crisis, the cerebrovascular reserve capacity was then evaluated with acetazolamide (Diamox(R)). Results: BTO could be performed without neurological com plications or carotid dissection. In eight (15%) patients BTO had to b e interrupted previously due to neurological symptoms or a delta-EEG. These patients and patients with highly pathological test results in S PECT imaging (n = 9) or TCD (n = 3) were excluded from permanent carot id occlusion. Ten (19%) patients were definitely occluded without hemo dynamic complications, but two patients suffered embolic infarctions, which can not be predicted by this procedure. In two patients with a s evere hypoperfusion in SPECT imaging, the ICA had to be ligated under emergency conditions following a carotid rupture. Predictably, a hemod ynamic infarction occurred postoperatively in both patients. Conclusio ns: The multimodal BTO with brain perfusion imaging (HMPAO-SPECT) and quantitative blood flow monitoring (TCD) allows a hemodynamic stroke r isk assessment prior to permanent occlusion of the ICA. The procedure is important for planning of the therapeutic strategy and for the preo perative dialogue with the patient. Embolic ischemic complications can not be predicted.