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Shouichi Itoh, Tomio Sasaki, Akio Asai, and Yoshiyuki Kuchino

✓ The authors investigated the roles of endothelin (ET)-1 and the ETA receptor in the pathogenesis of delayed cerebral vasospasm following subarachnoid hemorrhage (SAH). A study was made of the preventive effect of a novel ETA receptor antagonist, BQ-123, on vasospasm and the expression of the ETA receptor messenger ribonucleic acid (mRNA) using a canine two-hemorrhage SAH model. Continuous intrathecal administration of BQ-123 (5 × 10−6 mol/day) prevented narrowing of the basilar artery on Day 7 after SAH in 97.6% of cases in the study group versus 70.7% of cases in the control group (p < 0.05). While expression of the mRNA-coding ETA receptor was not detected in the control animals, it markedly increased on Day 3 after SAH and was also detected on Day 7. The results suggest that endothelin-1 and the ETA receptor participate in the pathogenesis of delayed cerebral vasospasm following SAH.

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Takamitsu Fujimaki, Masao Matsutani, Akio Asai, Takeshi Kohno, and Morio Koike

✓ A case of cerebral venous thrombosis due to polycythemia secondary to adaptation to a high altitude is reported. A 27-year-old previously healthy man developed severe neurological symptoms after climbing 8511m. Computerized tomography and cerebral angiography suggested hemorrhagic infarction or intratumoral hemorrhage, and a craniotomy was performed. Pathological examination confirmed the diagnosis of hemorrhagic infarction secondary to cortical venous thrombosis. The etiology and incidence of cerebral venous thrombosis secondary to polycythemia are discussed.

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Yumiko Komori, Masahiro Nonaka, Takamasa Kamei, Junichi Takeda, Tetsuo Hashiba, Kunikazu Yoshimura, and Akio Asai

The authors present the case of a 1-month-old girl with a lumbosacral lipoma who then developed an extracanalicular syrinx and experienced rapid deterioration. The patient’s initial MRI study, obtained before she became symptomatic, revealed a spinal lipoma with a syrinx in contact with the lipoma-cord interface. She was initially asymptomatic but developed loss of motor function in the left leg 14 days after MRI. Emergency surgery was performed. Intraoperative findings revealed a swollen spinal cord. Lipomatous tissue on the caudal side of the conus was removed subtotally, and the central canal was opened. Expansion of the syrinx was observed intraoperatively. Postoperatively, the patient’s left leg paresis remained. Postoperative MRI revealed rostral and extracanalicular expansion of the syrinx. This is the first report on the rapid deterioration of a conus lipoma due to extracanalicular expansion of a syrinx. Careful follow-up and repeat MRI should be considered for patients with spinal lipomas with syringomyelia, especially when the syrinx is attached to the lipoma-cord interface.

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Akio Asai, Soichiro Shibui, Marvin Barker, Martin Vanderlaan, Joe W. Gray, and Takao Hoshino

✓ Rats with 9L brain tumors received intraperitoneal injections of iododeoxyuridine (IUdR) and bromodeoxyuridine (BUdR) to estimate the duration of the deoxyribonucleic acid (DNA) synthesis phase (Ts) and the potential doubling time (Tp) of individual tumors. Different sequences and intervals (2 or 3 hours) of IUdR and BUdR administration were evaluated. After denaturation, tumor sections were reacted with Br-3, a monoclonal antibody that identifies only BUdR, and then were stained immunohistochemically by the avidinbiotin complex method. An antibody that recognizes both IUdR and BUdR, IU-4, was applied to the sections and identified by the alkaline phosphatase-antialkaline phosphatase method. Nuclei labeled only with IUdR stained blue, while those labeled with BUdR or with BUdR and IUdR stained brown. The fraction of cells that either left or entered the S-phase during the time between administration of IUdR and BUdR was measured to calculate Ts and Tp, assuming that the labeled cohort completed the DNA synthesis at a constant rate. The Ts was 8.8 hours (coefficient of variation (cv) = 0.05) and the Tp was 64.2 hours (cv = 0.08). The sequence and interval of administration of IUdR and BUdR had a minimal effect on Ts and Tp. In studies of 9L cells in monolayer culture, the Ts was 9.6 hours (cv = 0.08) and the Tp was 30.6 hours (cv = 0.06). Double labeling with BUdR and IUdR allows the duration of the S-phase and potential doubling time of individual brain tumors to be estimated in situ from a single biopsy specimen.

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Akio Asai, Masao Matsutani, Takeshi Kohno, Takamitsu Fujimaki, Hideki Tanaka, Kenji Kawaguchi, Morio Koike, and Kintomo Takakura

✓ An extremely rare case of isolated histioproliferative lesions arising from the subarachnoid space of the left occipital convexity and the orbit is presented. The presence of histiocytes showing lymphophagocytosis and positivity for S-100 protein staining confirmed that the lesions represented extranodal forms of sinus histiocytosis with massive lymphadenopathy.

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Akio Morita, Shigeo Sora, Mamoru Mitsuishi, Shinichi Warisawa, Katopo Suruman, Daisuke Asai, Junpei Arata, Shoichi Baba, Hidechika Takahashi, Ryo Mochizuki, and Takaaki Kirino

Object. To enhance the surgeon's dexterity and maneuverability in the deep surgical field, the authors developed a master—slave microsurgical robotic system. This concept and the results of preliminary experiments are reported in this paper.

Methods. The system has a master control unit, which conveys motion commands in six degrees of freedom (X, Y, and Z directions; rotation; tip flexion; and grasping) to two arms. The slave manipulator has a hanging base with an additional six degrees of freedom; it holds a motorized operating unit with two manipulators (5 mm in diameter, 18 cm in length). The accuracy of the prototype in both shallow and deep surgical fields was compared with routine freehand microsurgery. Closure of a partial arteriotomy and complete end-to-end anastomosis of the carotid artery (CA) in the deep operative field were performed in 20 Wistar rats. Three routine surgical procedures were also performed in cadavers.

The accuracy of pointing with the nondominant hand in the deep surgical field was significantly improved through the use of robotics. The authors successfully closed the partial arteriotomy and completely anastomosed the rat CAs in the deep surgical field. The time needed for stitching was significantly shortened over the course of the first 10 rat experiments. The robotic instruments also moved satisfactorily in cadavers, but the manipulators still need to be smaller to fit into the narrow intracranial space.

Conclusions. Computer-controlled surgical manipulation will be an important tool for neurosurgery, and preliminary experiments involving this robotic system demonstrate its promising maneuverability.

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Akio Asai, Hisashi Yamada, Sadayoshi Murata, Akira Matsuno, Kazuo Tsutsumi, Tamiko Takemura, Masao Matsutani, and Kintomo Takakura

✓ A rare case of leiomyosarcoma arising from the dura mater is presented. A definite histological diagnosis was based on the electron microscopic features. Extensive removal of the tumor and postoperative radiation therapy resulted in complete remission. The etiology and the origin of this tumor are discussed.

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Takamasa Kamei, Masahiro Nonaka, Yoshiko Uemura, Yasuo Yamanouchi, Yumiko Komori, Ryoichi Iwata, Junichi Takeda, Tetsuo Hashiba, Kunikazu Yoshimura, and Akio Asai

Rathke’s cleft cyst is a cystic disease that occurs in the sella turcica or, occasionally, in the suprasellar area. An ectopic Rathke’s cleft cyst is extremely rare, and its nature is less well understood. The authors report the case of a 14-year-old girl who presented with a growing cystic lesion in the prepontine cistern, immediately behind the dorsum sellae. Preoperative imaging and intraoperative investigation showed part of the cyst wall continuing into the dorsum sellae, to the pituitary gland. The cisternal portion of the cyst wall was totally resected via a right subtemporal approach. Histopathological examination of the cyst wall showed a monolayer of ciliated cells, identical to those of Rathke’s cleft cyst. To the best of the authors’ knowledge, this represents the first pediatric case of Rathke’s cleft cyst occurring in the prepontine cistern.

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Ai Kunizawa, Masayuki Fujioka, Satoshi Suzuki, Takashi Ryu, Akio Asai, Keiji Kawamoto, and Yasuhide Kitazawa

Spontaneous spinal epidural hematoma (SSEH) is rare. Its etiology remains controversial; however, spinal venous wall susceptibility to intravenous pressure change and the resultant venous rupture seem to be involved. The authors report a case of SSEH dorsal to the spine producing acute anterior spinal cord syndrome. A posterior SSEH between the C-3 and T-5 levels caused progressive tetraparesis and the disappearance of superficial body sensation below the level of C-8, although deep sensation remained completely intact. This neurological false localizing sign seems to have resulted from counterforce by preexisting asymptomatic cervical intervertebral disc herniation at the C6–7 levels inducing direct pressure on the anterior spinal cord. This case is the first reported instance of posterior cervical SSEH manifesting acute anterior spinal cord syndrome as its false localizing sign.

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William P. Vandertop, Akio Asai, Harold J. Hoffman, James M. Drake, Robin P. Humphreys, James T. Rutka, and Laurence E. Becker

✓ Between January, 1981, and July, 1991, 17 infants under 1 month of age were admitted to The Hospital for Sick Children with the signs and symptoms of a Chiari II malformation. These patients' presentation included swallowing difficulty (71%), stridor (59%), apneic spells (29%), aspiration (12%), weakness of cry (18%), and arm weakness (53%). Decompression of the Chiari II malformation was performed in all patients, with a time interval between onset of symptoms and surgery ranging from 1 to 121 days. Fifteen patients (88%) remain alive, all of whom have shown a complete recovery. The mean follow-up period in this group of patients was 65 months. Two patients died, one due to respiratory arrest 8 months after decompression and the other because of shunt infection and peritonitis 7 years after decompression. These results support the concept that compressive forces, rather than a primary intrinsic disorder of the brain-stem nuclei, play a crucial etiological role in the development of a symptomatic Chiari II malformation. Early recognition of the symptoms of Chiari II malformation should be followed by immediate decompressive laminectomy in order to promote a prompt and full neurological recovery.