This study was performed to examine the effects of mental arithmetic (MA) on cerebral blood flow (CBF) . We recorded the blood flow velocity before, during and after mental arithmetic in the bilateral internal carotid arteries (ICA) and vertebral arteries (VA) simultaneously and continuously in nine healthy males (25.8±7.2 y.o.) . The subjects performed MA for 30-60 seconds. The mean values of blood flow velocity (BFV) were calculated for each pulse using an FFT-analyzer. We observed BFV in 24 ICAs and 9 VAs in all of the 9 subjects. During MA in comparison with the period before MA, BFV in the 10 of ICAs and the 3 of VAs increased significantly, however BFV in the other 3 of ICAs decreased significantly and the rest 11 of ICAs was unchanged. The number of increases was significantly higher than that of decreases and no changes. After MA compared with the period during MA, BFV in the 3 ICAs and the 3 VAs decreased significantly, however BFV in one ICA increased significantly and the rest of 20 ICAs was unchanged. Also the blood pressure and heart rate were unchanged during MA. In summary, our study identified and documented statistically significant changes in cerebral blood flow velocity during MA. And it was suggested that some other factors, such as mental state, have influence on cerebral blood flow velocity during MA.
Using duplex carotid ultrasonography, we measured the mean flow velocity in common carotid artery and examined the atherosclerotic lesions (plaque) in 30 patients with lacunar infarction (L group) and 99 patients without cerebral infarction (C group) . L group was diagnosed on clinical symptomatology and infarction size (≤15 mm) by brain CT or MRI. The mean flow velocity (25.3±4.7cm/s) in the L group was significantly lower than that (31.1±7.4cm/s) in the C group. The difference of the mean flow velocities between the L and C groups was considered to be based on the difference of peripheral resistance. In the L group, the mean flow velocity on the affected side was not significantly different from that on unaffected side. Incidence of atherosclerotic lesions (plaque) in the L group was significantly higher than that in the C group. These results suggested that the cerebral atherosclerosis was more advanced in patients with lacunar infarction than in those without brain infarction.
To assess whether the changes in blood pressure during general anesthesia with epidural block affect the cerebral circulation in aged patients, we measured blood flow velocity (MV) in the middle cerebral artery by transcranial Doppler ultrasound method (TCD) in patients without hypertension (H (-) ) group (n=10) (mean age: 75±6 years), patients with hypertension (H (+) ) group (n=10) (mean age: 73±2 years) and control (C) group (n=7) (47±7 years) . The decreasing values of mean blood pressure was 24±8 mmHg (mean±SD) in H (-) group, 25±6 mmHg in H (+) group and 23±8 mmHg in C group respectively, according epidural block. After epidural block, the change of MV was 88±20% in H (-) group, 81±15% in H (+) group and 101±10% in C group, respectively, compared with pre-epidural block. MV decreased significantly in H (+) group compared with control group (P<0.05) . The results suggest that cerebral autoregulation may be impaired in aged patients with hypertension, and careful management must be necessary during anesthesia in aged patients.
Ultrasonic surgical scalpels have recently been used for brain tumor surgery. The Niic ultrasonic surgical aspirator (NUSA) was developed in conjunction with Nippon infrared industries Co., LTD. (NIIC) . The instrument consists of a handpiece and a control and power console. The“NUSA”has no cooling system because the ultrasonic power is generated by plumbi zircon titanate (PZT) . Thus, the handpiece is very light (150, 160 gram) and can be manipulated with one hand like a regular suction tube. So, the“NUSA”and a bipolar coagulator can be used simultaneously. Furthermore, an irrigation tube is attached to the suction tube in parallel, and can be moved around the suction tube. Targetted irrigation is thus possible with this new system. The“NUSA”has been used in 150 cases to date. The tumors treated have included gliomas, meningiomas, neurinomas and metastatic tumors. The“NUSA”facilitated the removal of tumors, reduced intraoperative bleeding and shortened the operating time. The handpiece can be manipulated under an operating microscope and is very useful for the removal of tumors even in the cerebello-pontine angle or the ventricular systems.
Recently, noninvasive demonstration of major cerebral arteries has become possible by using transcranial color-coded duplex sonography. We carried out neurosurgical operations in 11 patients with brain tumor and in 1 patient with vascular malformation employing intraoperative Brightness mode (B-mode), color flow imaging and power Doppler imaging (CFI and PDI) to identify mass lesions and, the brain and vascular structure. Ultrasound imaging was performed with an Ultramark 9 HDI (Advanced Technology Laboratories, U.S.A.) using various kinds of scanning probe. Real-time monitoring of B-mode imaging aids in guidance when biopsy probes are applied for brain tumor biopsy as well as in the identification of the localization of tumor masses. CFI and PDI can also demonstrate major cerebral vessels and improve our understanding of the context of brain structure and pathological lesions. PDI was able to reveal slow flow at occult arteriovenous malformations, which failed to be depicted as flow vessels by angiography. In conclusion, intraoperative ultrasound imaging may be useful as a mean of real time monitoring and assists us in performing neurological operations safely.