Kazuhiro Kishikawa

Diagnostic Impact of Transcranial Color-Coded Real-Time Sonography With Echo Contrast Agents for Hyperperfusion Syndrome After Carotid Endarterectomy

Background and Purpose— The purpose of the present study was to evaluate availability of transcranial color-coded real-time sonography (TCCS) to detect hyperperfusion after carotid endarterectomy (CEA). Methods— This prospective study included 105 consecutive patients who underwent CEA for severe carotid stenosis. TCCS with echo contrast agents was performed serially to evaluate flow velocity of the middle cerebral artery (MCA). Regional cerebral blood flow (rCBF) and vasodilatory capacity of the MCA territory were evaluated using single-photon emission computed tomography. We compared the changes in MCA flow velocity with rCBF. Results— Using echo contrast agents, we could evaluate the MCA flow in 95 (90%) of 105 patients. Twelve patients showed hyperperfusion syndrome. Changes in the MCA mean flow velocity (MFV) before and 4 days after CEA were significantly correlated with those in rCBF (r =.48; P <.0001). An increase of >50% in MCA MFV was observed within 4 days after CEA in all 12 patients with hyperperfusion syndrome. Multivariate analysis revealed that reduced vasodilatory capacity (odds ratio, 0.14; 95% CI, 0.04 to 0.46) was an independent risk factor for a 1.5-fold increase in the MFV of MCA ipsilateral to CEA. Conclusions— Findings of a 1.5-fold increase in the MCA MFV can accurately identify those patients with high risk of developing post-CEA hyperperfusion syndrome. TCCS with echo contrast agents is available for the evaluation of hyperperfusion after CEA.

Effects of carotid endarterectomy on cerebral blood flow and neuropsychological test performance in patients with high-grade carotid stenosis

We examined the changes in cognitive function following carotid endarterectomy (CEA) in relation to the cerebral blood flow (CBF) in patients with high-grade carotid stenosis. The subjects consisted of 23 patients who underwent CEA and 17 controls matched by age and education. Single photon emission computed tomography (SPECT) and neuropsychological tests were performed 2 weeks before and 4 weeks after CEA in all patients. The preoperative CBF tests revealed a decreased vasodilatory reserve in the ipsilateral cerebral hemisphere in nine patients, which was increased after CEA. In these patients, the grade of carotid stenosis was significantly higher than in those with a normal perfusion reserve (90.2+/-8.1% vs. 78.6+/-11.3%, respectively, p<0.05). In the patient group, the postoperative scores (27.2+/-2.9) of the mini-mental state examination (MMSE) improved significantly over the preoperative ones (26.1+/-3.2, p<0.05). Moreover, the scores in the block-design test after CEA (86.8+/-19.8) were significantly higher than those before the operation (81.8+/-22.3, p<0.01). The error score in immediate retention improved from 9.0+/-3.1 to 7.7+/-4.0 following CEA (p<0.05). In the control group, none of the test scores showed significant improvement between the first and second tests. In the patients with an impaired vasodilatory reserve, the mean score of the block-design test significantly improved from 65.6+/-22.1 to 74.0+/-19.2 after CEA compared with those in patients without impairment (p<0.05). High-grade carotid stenosis was thus concluded to cause cognitive impairment due to cerebral hemodynamic failure, which is presumably reversed by CEA.

Accuracy of Conventional plus Transoral Carotid Ultrasonography in Distinguishing Pseudo-Occlusion from Total Occlusion of the Internal Carotid Artery

Background: To investigate the accuracy of conventional carotid ultrasonography (CCU) combined with transoral carotid ultrasonography (TOCU) for distinguishing pseudo-occlusion from total occlusion of the internal carotid artery (ICA). Methods: This study included 95 patients who were suspected of having an occlusion of the ICA on magnetic resonance angiography (MRA) and underwent both CCU and conventional digital subtraction angiography (DSA) in order to confirm the diagnosis. TOCU was also performed to observe the cervical portion of the ICA distal to the stenosis. We compared the ultrasonographic findings with the DSA findings. Results: Twelve of the 95 patients were defined as having an ICA pseudo-occlusion on DSA. On B-mode images with CCU color Doppler, slight residual flow signals in the ICA lumen were shown in 20 patients. Among them, 2 patients had a pulsed Doppler waveform of the distal ICA occlusion pattern. Among the remaining 18 patients, 4 had a pulsed Doppler waveform of the to and fro flow pattern, and 14 had a weak antegrade flow pattern in the ICA lumen. The conventional ultrasonographic method showed 100% sensitivity with 93% specificity for diagnosing an ICA pseudo-occlusion. The addition of TOCU findings increased the specificity to 98%. In 2 patients, who were overdiagnosed as having an ICA pseudo-occlusion even using TOCU, DSA revealed an occlusion of the ICA distal to the ophthalmic artery with a severe stenosis of the proximal ICA. Conclusions: Using conventional and transoral carotid ultrasonography, an ICA pseudo-occlusion can be diagnosed with higher accuracy.

Transoral Carotid Ultrasonography as a Diagnostic Aid in Patients with Severe Carotid Stenosis

Evaluation of the distal portion of the extracranial internal carotid artery (ICA) is indispensable for the judgment of whether surgical treatment for high-grade carotid stenosis is preferable or not. When the ICA is occluded or severely stenosed by an organic lesion along the long segment, carotid endarterectomy (CEA) is abandoned. On the other hand, CEA may be beneficial in patients with severe carotid stenosis which is situated only in the restricted lesion of the proximal portion of the ICA. Conventional carotid ultrasonography sometimes cannot provide sufficient information due to calcified plaque and/or high position of bifurcation. Newly developed transoral carotid ultrasonography (TOCU) enables us to observe the distal extracranial ICA and distinguish the differential diagnosis. We herein report 3 cases of severe carotid stenosis in which TOCU provided the necessary information obtained neither by conventional carotid ultrasonography nor by angiogram. We concluded that TOCU provides prerequisite information in certain cases in which CEA is considered.