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Yukihiko Fujii, Shigekazu Takeuchi, Osamu Sasaki, Takashi Minakawa, Tetsuo Koike and Ryuichi Tanaka

✓ This study was undertaken to elucidate comprehensively the serial changes occurring in hemostatic systems after aneurysmal subarachnoid hemorrhage (SAH) and thereby to ascertain whether the examination of the integrity of these systems is helpful in predicting delayed ischemic neurological deficits (DINDs). The authors examined 117 patients admitted to the hospital within 24 hours after onset of SAH. Blood samples were collected from each patient on Days 0 (at admission), 3, 6, 14, and 30. A number of hemostatic parameters were examined in these samples, and the relationships between their changes and DINDs were assessed. Eighteen (15.4%) of the patients exhibited DINDs, and their frequency increased as the severity of subarachnoid clotting increased. Also, the frequency of DINDs was significantly higher in the patients with hydrocephalus on initial computerized tomography (CT) scans than in those without hydrocephalus. Regarding the hemostatic parameters at admission, there was no significant difference between the patients with and without DINDs. On Day 3, however, the fibrinogen and D-dimer levels were higher in the patients with than in those without DINDs. The fibrinogen and thrombin—antithrombin complex levels on Day 6 and the D-dimer level on Day 14 in the patients with DINDs were higher than the corresponding levels in those without DINDs. Multivariate analyses revealed that the following variables (in order of importance) were independent predictors of DINDs: the levels of D-dimer on Day 3, fibrinogen on Day 6, and the presence of hydrocephalus on admission. These data indicate that the levels of hemostatic parameters in concert with the CT findings may enable us to predict the appearance of DINDs.

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Masafumi Fukuda, Makoto Oishi, Tetsuya Hiraishi, Akihiko Saito and Yukihiko Fujii

Object

The purpose of this study was to determine whether monitoring of pharyngeal motor evoked potentials (PhMEPs) elicited by transcranial electrical stimulation during skull base tumor surgery might be useful for predicting postoperative swallowing deterioration.

Methods

The authors analyzed PhMEPs in 21 patients during 22 surgical procedures for the treatment of skull base tumors. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (220–550 V). Pharyngeal MEPs were recorded from the posterior wall of the pharynx through a modified endotracheal tube. The correlation between the final/baseline PhMEP ratio and postoperative swallowing function was examined.

Results

Postoperative swallowing function was significantly (p < 0.05), although not strongly (r = −0.47), correlated with the final/baseline PhMEP ratio. A PhMEP ratio < 50% was recorded during 4 of 22 procedures; in all 4 of these cases, the patients experienced postoperative deterioration of swallowing function. After 18 procedures, the PhMEP ratios remained > 50%; nevertheless, after 4 (22.2%) of these 18 procedures, patients showed deterioration of swallowing function.

Conclusions

Intraoperative PhMEP monitoring can be useful for predicting swallowing deterioration following skull base surgery, especially in patients with swallowing disturbances that are mainly due to reduction in the motor functions of the pharyngeal muscles.

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Yukihiko Fujii, Shigekazu Takeuchi, Osamu Sasaki, Takashi Minakawa, Tetsuo Koike and Ryuichi Tanaka

✓ To determine the incidence of, and risk factors for, the occurrence of rebleeding between admission and early operation (ultra-early rebleeding) in patients with spontaneous subarachnoid hemorrhage (SAH), the authors reviewed the cases of 179 patients admitted within 24 hours after their last attack of SAH. Thirty-one (17.3%) of these patients had ultra-early rebleeding despite scheduling of early operation (within 24 hours after admission). The incidence of rebleeding significantly decreased as the time interval between the last attack and admission increased. Patients with rebleeding before admission, high systolic blood pressure, intracerebral or intraventricular hematoma, those in poor neurological condition on admission, and those who underwent angiography within 6 hours of the last SAH were significantly more likely to have ultra-early rebleeding than those without these factors. The incidence of rebleeding also significantly increased as levels of enhancement of platelet sensitivity and thrombin—antithrombin complex increased. Multivariate analysis revealed that the following three factors were independently associated with ultra-early rebleeding: the level of enhancement of platelet sensitivity; the time interval between the last attack and admission; and the level of thrombin—antithrombin complex. On the basis of these findings, the authors suggest that many of the risk factors for ultra-early rebleeding are interrelated. A particularly high risk of ultra-early rebleeding was observed in those patients 1) who had platelet hypoaggregability; 2) who were admitted shortly after their last SAH; and 3) whose thrombin—antithrombin complex levels were extremely high and were thus in severe clinical condition.

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Kazuhiko Nishino, Hitoshi Hasegawa, Kenichi Morita, Masafumi Fukuda, Yasushi Ito, Yukihiko Fujii and Mitsuya Sato

OBJECTIVE

Arteriovenous malformations (AVMs) in the cerebellopontine angle cistern (CPAC) are specific lesions that can cause neurovascular compression syndromes as well as intracranial hemorrhage. Although case reports describing the CPAC AVMs, especially those presenting with trigeminal neuralgia (TN), have been accumulating by degrees, the pathophysiology of CPAC AVMs remains obscure. The authors' purpose in the present study was to evaluate the clinical and radiographic features of CPAC AVMs as well as the treatment options.

METHODS

This study defined a CPAC AVM as a small AVM predominantly located in the CPAC with minimal extension into the pial surface of the brainstem and closely associated with cranial nerves. All patients with CPAC AVMs treated in the authors' affiliated hospitals over a 16-year period were retrospectively identified. Clinical charts, imaging studies, and treatment options were evaluated.

RESULTS

Ten patients (6 men and 4 women), ranging in age from 56 to 77 years (mean 65.6 years), were diagnosed with CPAC AVMs according to the authors' definition. Six patients presented with hemorrhage, 3 with TN, and the remaining patient developed a hemorrhage subsequent to TN. Seven AVMs were associated with the trigeminal nerve (Group V), and 3 with the facial-vestibulocochlear nerve complex (Group VII–VIII). All patients in Group VII–VIII presented with the hemorrhage instead of hemifacial spasm. Regarding angioarchitecture, the intrinsic pontine arteries provided the blood supply for all CPAC AVMs in Group V. In addition, 5 of 7 AVMs with hemorrhagic episodes accompanied flow-related aneurysms, although no aneurysm was detected in patients with TN alone. With respect to treatment, all patients with hemorrhagic presentation underwent Gamma Knife surgery (GKS), resulting in favorable outcomes except for 1 patient who experienced rebleeding after GKS, which was caused by the repeated rupture of a feeder aneurysm. The AVMs causing TN were managed with surgery, GKS, or a combination, according to the nidus-nerve relationship. All patients eventually obtained pain relief.

CONCLUSIONS

Clinical symptoms caused by CPAC AVMs occur at an older age compared with AVMs in other locations; CPAC AVMs also have distinctive angioarchitectures according to their location in the CPAC. Although GKS is likely to be an effective treatment option for the CPAC AVMs with hemorrhagic presentations, it seems ideal to obliterate the flow-related aneurysms before performing GKS, although this is frequently challenging. For CPAC AVMs with TN, it is important to evaluate the nidus-nerve relationship before treatment, and GKS is especially useful for patients who do not require urgent pain relief.

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Kazuhiko Nishino, Yasushi Ito, Takatoshi Sorimachi, Junsuke Shimbo and Yukihiko Fujii

Sturge-Weber syndrome (SWS) is a neurocutaneous disorder presenting with a facial port-wine stain, along with an occipital leptomeningeal angiomatosis that is typically located ipsilateral to the stain. In this paper, the authors present a rare case of SWS associated with an arteriovenous malformation (AVM) instead of an angiomatosis in the ipsilateral occipital lobe. While the patient was in the care of the authors, the AVM progressively enlarged, and was accompanied by progressive stenoocclusive changes of the venous system. The resulting brain edema finally brought about a serious neurological condition 13 years after the initial diagnosis. Transarterial embolization and medical treatments decreased the edema. Subsequently, however, a large intraparenchymal cyst appeared, aggravating the patient's motor weakness. Aspiration of the cyst ameliorated these symptoms. The analysis of the fluid from the cyst revealed that it contained a very high concentration of protein. Although there is no proven pathogenic mechanism to explain these protein concentrations and the enlargement of the AVM, the authors hypothesize that the progressive edema resulted from a synergic augmentation of the inflow from the AVM and the progressive obstruction of venous drainage that is a hallmark of SWS. The formation of the cyst probably resulted from the blood vessel hyperpermeability that is inherent to SWS.

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Yukihiko Fujii, Ryuichi Tanaka, Shigekazu Takeuchi, Tetsuo Koike, Takashi Minakawa and Osamu Sasaki

✓ In order to evaluate the incidence and risk factors of hematoma enlargement in spontaneous intracerebral hemorrhage (ICH), 419 cases of ICH were reviewed. The first computerized tomography (CT) scan was performed within 24 hours of onset and the second within 24 hours of admission; a blood sample was taken for laboratory examination within 1 hour of admission. In 60 patients (14.3%) the second CT scan showed an enlarged hematoma. The incidence of enlargement significantly decreased with time (p < 0.05) and significantly increased with the severity of liver dysfunction and the volume of the hematoma on the first CT scan. Patients with an irregularly shaped hematoma had a higher risk of hematoma growth than those with a round hematoma. In addition, patients with hematoma enlargement were more likely to have coagulation abnormalities (low platelet counts and low levels of fibrinogen, α2-antiplasmin activity and platelet aggregation). Moreover, hematoma growth was associated with a poor clinical outcome.

It is concluded that patients admitted to a hospital within 6 hours of onset of ICH, especially those admitted within 2 hours, and patients with liver dysfunction or irregularly shaped large hematomas should be closely observed for at least 6 hours after onset in preparation for emergency surgery, since the risk of hematoma growth in these circumstances is high.

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Tsutomu Nakada, Naoki Nakayama, Yukihiko Fujii and Ingrid L. Kwee

✓ The utility of three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) axonography, a method sensitive to neuronal fibers and their directionality, was investigated in the clinical setting using a 3-tesla MR imaging system based on a General Electric Signa platform. The study focused on healthy volunteers and patients with common structural central nervous system disorders, namely chronic infarction, brainstem cavernous hemangioma, supratentorial meningioma, and astrocytoma. Three orthogonal anisotropic diffusion-weighted images were first obtained. Three primary colors were each assigned to a diffusion-weighted image, respectively, and the images were subsequently combined into a single-color image in full-color spectrum (3DAC MR axonography image). Fiber-tract definition in the cerebral peduncle of the midbrain of healthy volunteers showed intersubject variation, with two general patterns recognized: dispersed (60% of cases) and compact (40% of cases). Pathological alterations in the fiber tracts were readily identified in cases involving wallerian degeneration of the pyramidal tract, as illustrated in the cases of chronic infarction. Displacement of major tracts, such as the medial lemniscus or corticospinal tract, as well as fiber directionality, was also easily recognized in cases of mass lesions. As an imaging method uniquely capable of providing information regarding axonal connectivity, 3DAC MR axonography appears to have promising potential for routine clinical application.

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Takatoshi Sorimachi, Yukihiko Fujii, Kenichi Morita and Ryuichi Tanaka

Object

Hematoma enlargement is a major cause of poor outcome in patients with intracerebral hemorrhage (ICH). A combination of rapid administration of antifibrinolytics and strict blood pressure (BP) control for prevention of hematoma enlargement has been recently reported. The authors examined the incidence and predictors of hematoma enlargement in patients with ICH who were treated with this therapy.

Methods

Rapid administration of antifibrinolytic agents consisted of intravenous administration of 2 g tranexamic acid over 10 minutes. Systolic BP was strictly maintained below 150 mm Hg using intravenous nicardipine. Immediately after diagnosis of ICH on computed tomography (CT), 188 patients who were admitted within 24 hours of symptom onset were treated with a combination of rapid administration of antifibrinolytic agents and BP control. Hematoma enlargement was determined on the basis of a second CT scan performed the day after admission. Several factors, including those that have been reported to affect hematoma enlargement, were compared between patients with and without hematoma enlargement.

Hematoma enlargement (≥ 20% volume increase) was observed in eight (4.3%) of 188 patients. Previous use of antiplatelet agents was significantly more frequent in patients with hematoma enlargement (p < 0.05). No significant between-group difference was found for any other factors.

Conclusions

Previous use of antiplatelet agents was a predictor of hematoma enlargement in patients with ICH treated with rapid administration of antifibrinolytic agents and BP control.

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Toru Watanabe, Yoshiho Honda, Yukihiko Fujii, Miyako Koyama and Ryuichi Tanaka

Object. The purposes of this study were to evaluate the serial changes in diffusion anisotropy of the brain, probably reflecting axonal function in brain-dead patients, and thus to explore the possibility of quantitatively estimating the risk of brain death.

Methods. Ten patients suffering from stroke with or without impending brain death and 10 healthy volunteers were studied using three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) axonography with the aid of a 1.5-tesla MR imaging system. To detect changes in the diffusion anisotropy of neural bundles, the corticospinal tract was evaluated.

Diffusion anisotropy of short axonal fibers decreased immediately after apparent brain death. Whereas the trichromatic coefficients of the corticospinal tract greatly diminished between 6 and 12 hours after apparent brain death, the coefficients of the corpus callosum and the optic radiation decreased in less time, that is, between 1 and 6 hours. The coefficients of these three bundles turned isotropic between 24 and 44 hours after apparent brain death.

Conclusions. Results of 3DAC MR axonography revealed that diffusion anisotropy of neural bundles diminished between 1 and 12 hours after the onset of apparent brain death, probably depending on the length of the bundles, and disappeared between 24 and 44 hours after the onset of brain death, which might reflect dynamic changes of axonal structure and indirectly herald axonal dysfunction. These findings seem to be greatly helpful in establishing an appropriate method to estimate the risk of brain death quantitatively and in forming the basis of future definitions of brain death.

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Makoto Oishi, Masafumi Fukuda, Tetsuya Hiraishi, Naoki Yajima, Yosuke Sato and Yukihiko Fujii

Object

The purpose of this paper is to report on the authors' advanced presurgical interactive virtual simulation technique using a 3D computer graphics model for microvascular decompression (MVD) surgery.

Methods

The authors performed interactive virtual simulation prior to surgery in 26 patients with trigeminal neuralgia or hemifacial spasm. The 3D computer graphics models for interactive virtual simulation were composed of the brainstem, cerebellum, cranial nerves, vessels, and skull individually created by the image analysis, including segmentation, surface rendering, and data fusion for data collected by 3-T MRI and 64-row multidetector CT systems. Interactive virtual simulation was performed by employing novel computer-aided design software with manipulation of a haptic device to imitate the surgical procedures of bone drilling and retraction of the cerebellum. The findings were compared with intraoperative findings.

Results

In all patients, interactive virtual simulation provided detailed and realistic surgical perspectives, of sufficient quality, representing the lateral suboccipital route. The causes of trigeminal neuralgia or hemifacial spasm determined by observing 3D computer graphics models were concordant with those identified intraoperatively in 25 (96%) of 26 patients, which was a significantly higher rate than the 73% concordance rate (concordance in 19 of 26 patients) obtained by review of 2D images only (p < 0.05). Surgeons evaluated interactive virtual simulation as having “prominent” utility for carrying out the entire surgical procedure in 50% of cases. It was evaluated as moderately useful or “supportive” in the other 50% of cases. There were no cases in which it was evaluated as having no utility. The utilities of interactive virtual simulation were associated with atypical or complex forms of neurovascular compression and structural restrictions in the surgical window. Finally, MVD procedures were performed as simulated in 23 (88%) of the 26 patients .

Conclusions

Our interactive virtual simulation using a 3D computer graphics model provided a realistic environment for performing virtual simulations prior to MVD surgery and enabled us to ascertain complex microsurgical anatomy.