TCD examination was performed in 71 patients with subarachnoid hemorrhage secondary to ruptured intracranial aneurysm. Delayed ischemic neurological deficits (DIND) accompanying vascular spasms were detected in 17 patients, but 10 of these recovered from the DIND within about 3 weeks. The TCD findings could be classified into four types according to their mean blood flow velocities (MBFV) . They consisted of: a) high pattern type, in which the MBFV had increased more than 100 cm/s (29 cases), b) low pattern type, in which the MBFV was less than 45cm/s (7cases), c) paradoxical pattern type, in which the MBFV was faster in the more peripheral regions (5 cases), and d) normal pattern type (30 cases) . From observation of the Doppler frequency, the sound of signals, and displayed waveforms, six characteristic findings were evaluated. (1) Filling-in of the systolic windows was observed in 16 out of 17 cases with DIND (23 out of 54 cases without DIND), (2) appearance of negative flow components was noted in all of the DIND cases (18 cases), (3) contour oscillation was viewed in 14 cases (10 cases), (4) high-intensity frequency was seen in 12 cases (14 cases), (5) musical murmur was heard in 8 cases (9 cases), and (6) disappearance of pulsatility was seen in 11 cases (10 cases) . From the observation of these six components, we made a“spasm score”on the TCD records. The score was 5.18±1.54 in the 17 patients with DIND, and 2.39±2.41 in 54 patients without DIND (p<0.001) . Sixteen patients out of 31 patients who had a spasm score of more than 3 suffured DIND, whereas, only one patient with a spasm score of less than 2 had DIND (p<0.01) . Hence this spasm score seemed to be very useful in the diagnosis of DIND in patients with vasospasms.
An intraoperative ultrasound scanner system (USS) was utilized on 28 patients (24 with intracranial lesions and four with spinal lesions) at Tsukuba University Hospital. The USS (Hitachi, Inc., Type EUB-415, Japan) was used for all patients. This apparatus includes a real-time display with a convex array and a 13-mm finger-tip transducer with a transmitting freguency of 5-6.5 MHz. Intraoperative ultrasonography is useful for reconf irming the size and location of the lesion and assists optimization of the operation procedure. It is also helpful before a tumor resection after craniotomy, during procedures such as cyst and hematoma puncture, and in diagnosing the cause of acute brain swelling during a tumor resection. It can also be used to check the removal of a tumor after resection. However, intraoperative ultrasonography after a tumor resection is less effective in detecting the residual tumor because small clots, hemostatic materials, and the postoperative cavity are obstacles to the ultrasound. Although there are limits to the resolution of the ultrasonography, it is very useful for a complete perspective of the operative procedure in the neurosurgical field.
[Purpose] It has been reported that the failure rate in recording middle cerebral artery (MCA) flow ranged from 20 to 40%. In our experience, this failure rate was about 10%. The detectability of MCA by transcranial Doppler ultrasonography (TCD) is influenced by several factors: (1) temporal bone thickness. (2) blood flow velocity. (3) pulsatility index. (4) age and sex of patients. (5) branching type of the MCA. (6) hematocrit, PaCO2, systolic blood pressure of the patients. and (7) technique. In this study, we investigated the detectability in 58 vessels of 33 subjects to assess the factors that affect Doppler detectability by TCD. [Materials and Methods] We analyzed three groups classified by the detectability, namely group A (easy detection) and group B (can detect MCA flow within 10 minutes) or group C (impossible to detect) . [Results] The significant factors that influenced the measurement of MCA flow were as follows: presence of thick temporal bone, a low flow velocity, and being an elderly female. The other factors had no apparent significance due to different conditions. [Conclusion] Thickness of the skull and blood flow velocity were considered to be two major factors that make it difficult to detect intracranial blood flow by TCD.