“Intraoperative Ultrasonography” has timely become a title of the “How I do It” sessions to be held at the 9th International Congress of Neurological Surgery, in India, in October 1989. Dr. Koivukangas in Oulu, Finland, and I were appointed as the chairmen. Porf. Sambasivan, chairman of the Scientific Committee, suggested that the whole planning, including the recruitment of experts would be in our hands.
At this point, it may be worthwhile to review the history of intraoperative use of ultrasonography. It was Lyle French in Minnesota who first applied the ultrasound probe to a cadaver brain. Oscar Sugar and Sumio Uematsu in Chicago are known to be the first in using the technique intraoperatively. However, Kenji Tanaka and the Juntendo group in Tokyo apparently wrote on Intraoperative use of ultrasonography as early as 1961. Shin Ueda wrote on intraoperative use of B mode ultrasonography in 1968. However, this technique has never gained general acceptance from neurosurgeons and gradually become almost forgotten with the introduction of CT scanners in the medical world.
I first used the real-time linear-array scanning probe intraoperatively on the brain surface on October 16, 1979, probably the first in the world. In December I changed to the sector-scanning probe, and performed needle aspiration and tumor biopsy under ultrasound monitoring. These experiences were published in 1980 and, in detail, in 1981.
In late 1980, two other similar reports were published. First, by Voorhies and Patterson, and secondly by Jonathan Rubin and co-authors in Chicago. The latter work dealt with an experience of a cerebellar tumor depicted by the dural application of a sector-scanning probe. Later in 1982, their group first published a paper concering the use of ultrasound probe over the spinal cord. In 1983, Joachim Gilsbach in Freiburg published a monograph on the intraoperative use of a mini-Doppler probe. In 1988, the merit of intraopertive color-flow Doppler imaging was introduced by William Chandler and his group in Ann Arbor, Michigan. I believe that the intraoperative use of ultrasound has now become widely accepted in the neurosurgical field.

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It was verified form the anatomical studies and the clinical applications that the quantitative and phasic blood flow velocity of the mid size to large arteries and veins in the cranium could be measured by our improved TCT (two dimensional echoencephalography) and the color TCDT.
[Anatomical study] From the examination of the thickness of the bone, the ultrasonic bony window on the temple is about 33mm in height and about 54mm in width calculated as the mean value of 55 skulls. The window has an adequate size for applring a conventional electric sector scan probe.
[TCT application] The power-increased TCT at 2.4MHz could supply the sector image of the brain st the horizontal, coronal and arbitrary planes through the temple, in which clinoid processes, venticles, the brain stem, the optical shiasma and the other structures could be shown. Simultaneously MCA, PCA, ACA and veins were captured and the phasic velocity sonograms of those vessels were recorded with ECG by the duplex method. Each artery flow and vein flow showed the well-known pulsatile flow pattern and the steady flow pattern respectivery. The pulsatile patternvanished on the MCA by the CCA compression test, and the steady flow increased rapidly on the superior petrosal vein by the varusarva test. Such phenomena on the cerebral circulation could be detected at the desired vessel on the TCT image.
[TCDT application] Although the desired vessel could be reasonably detected on TCT images by well trained clinicians, it is inadequate for calculating the quantitative velocity of the vessel and for reading the angle between the ultrasonic beam and the three dimensional flow direction. The reason is that the resolution of the ultrasonic image is inadequate to indicate the long axis view of the desired vessel and the length of the view is too short to read the angle. Even though the resolution was not improved by the color TCDT, the TCDT image made it easy to recognize the existence of the vessel in TCT image and to detect the beam angle of the vessel. By means of the TCDT image, the quantitative velocity could be measured at most of the large arteries and veins. And even on the MCA, the differences in the velocity could be quantified from the angle difference on the proximal and the peripheral.
Quantitative and various hemodynamic analyses for the intracranial circulation will be performed based upon true velocity information on the rather large arteries and veins measured by the color TCDT.

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The present study was carried out on a total of 56 patients, consisting of 8 patients prior to CEA (carotid endarterectomy) and 48 patients after CEA. Before or after ultrasonography in all of the patients, cerebrovas-cular angiography was performed. In the long-term follow-up of 48 patients after CEA (mean duration; 3.8 years), occlusion of the internal carotid artery was detected in 2 patients (4.2%) and images of 30%-50% recurrence of stenosis were found in 3 patients (6.2%) . In the patients not found to have stenosis, the endarter-ectomy portion of the carotid artery had an image of low sensitivity on the ultrasonogram, and this finding was interpreted as indicating that the vascular wall had become thinner. With regard to the 8 patients who experienced ultrasonography by prior to CEA, the findings of the ultrasonograms and the macroscopic findings of the excised atheromatous plaques, in all 8, were in agreement. In some cases, necrotic or fresh hemorrhagic lesions could be clearly distinguished in the blood vessel wall.
With ultrasonography, this procedure and this diagnostic technique can be performed repeatedly since it is non-invasive. Accordingly, we conclude that ultrasonography is a useful procedure for diagnosis prior to, and evaluation subsequent to CEA.

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The efficacy and limitation of several medical managements for raised intracranial pressure (ICP) were studied in 20 patients of severe head injury by use of transcranial Doppler (TCD) ultrasound. The effects of head elevation (horizontal, 15°, 30° and 45°), hyperventilation, barbiturate and the Sendai cocktail (20% mannitol, phenytoin and viatmin E) were evaluated by measuring blood flow velocity in the middle cerebral artery (MCAFV), ICP, cerebral perfusion pressure (CPP) and cerebrovascular CO₂ reactivity. The cerebrovascular CO₂ reactivity was investigated by obtaining the K value in the modified Olesen's formula of cerebral blood flow calculation.
As the degree of head elevation was increased, there was a gradual decrease in CPP in association with the decrease of MCAFV in 10 patients examined. These changes in CPP and MCAFV were remarkable in patients with lower GCS scores compared to those with higher GCS scores. The K values examined in 9 patients was low when the patient's GCS score were 5 or less. But as the patients GCS scores improved, the K values returned to normal nearly values. Barbiturates and the Sendai cocktail failed to improve raised ICP and also failed to improve raised ICP and reduced MCAFV in all patients whoes MCAFV were as low as 30-40cm/s before these treatments.
These results indicate that noninvasive study with TCD ultrasound can provide valuable informations on optimal therapeutic measures in patients with severe head injury.

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Ultrasonography was attempted to be utilized intraoperatively in 14 patients with medically intractable epilepsy. In nine of these 14 patients, epileptogenic foci were identified directly by intraoperative ultrasonogra-phy. All of the lesions with cystic components were clearly demonstrated. However, intraoperative ultrasonography could not depict satisfactorily all of the calcified lesions which had been demonstrated distinctly on preoperative CT and MRI. Even if ultrasonography could not demonstrate epileptogenic lesions, it was useful for determining localization of the lesions intraoperatively by three dimensional measurements of their location and extent by referring to sonographically identifiable structures, such as the ventricles, choroid plexus, falx, cerebellar tentorium and so on. Ultrasonography is considered to be useful as an intraoperative complement of structural studies in the surgical treatment of epilepsy.

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This study was performed to clarify the effects of brovincamine on the common carotid hemodynamics in patients with cerebral circulatory insufficiency.
A total of 38 patients including 14 males and 24 females were enrolled in this study. Their ages ranged from 55 to 84 years old and the mean age was 72 years old. They were given orally 60mg of brovincamine daily for 6 months. The common carotid hemodynamics by ultrasonic quantitative flow measurement system were evaluated during brovincamine administration.
Mean blood flow and mean blood velocity of the common carotid artery significantly increased in 1, 3, and 6 months after therapy. On the other hand, circulatory resistance of the brain significantly decreased in 1, 3, and 6 months after therapy.
These results indicate that brovincamine therapy may have beneficial effects on the common carotid hemodynamics in patients with cerebral circulatory insufficiency.

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