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Takeshi Hasegawa, Haruhide Ito, Shinjiro Yamamoto, Katsuhiko Haba and Hideaki Murata

✓ The authors describe a case of atypical unilateral prominent hyperostosis frontalis interna in a 50-year-old Japanese woman with psychiatric symptoms. Radiological, computerized tomographic, operative, and histological findings of this rare case are presented.

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Takeshi Hasegawa, Haruhide Ito, Katsuo Shoin, Yuzaburo Kogure, Toshihiko Kubota and Shinjiro Yamamoto

✓ A case of Nelson's syndrome with an adrenocorticotropic hormone-secreting pituitary chromophobe microadenoma is presented to demonstrate the potential capability of rapid sequential (dynamic) computerized tomography (CT) scanning for the diagnosis of a pituitary microadenoma that was isodense with the adjacent pituitary gland on conventional enhanced CT scanning. The dynamic CT scans showed transient high density in this microadenoma contrasting with the pituitary gland in the early-enhancement phase, and thereafter the contrast density was indistinguishable from that of the pituitary gland in the delayed-enhancement phase. For the detection of pituitary microadenoma, dynamic CT combined with subsequent delayed CT scanning can provide diagnostic and localizing information.

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Kenichi Saito, Haruhide Ito, Takeshi Hasegawa and Shinjiro Yamamoto

✓ Levels of the plasmin-α 2-plasmin inhibitor complex (PLN-A2PI complex) and α 2-plasmin inhibitor (A2PI) were determined by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies in 59 patients with 66 chronic subdural hematomas (SDH's). Normal concentrations of the PLN-A2PI complex and A2PI in plasma are below 0.8 µg/ml and 60.5 ± 16.1 µg/ml, respectively (mean ± 2 standard deviations). The hematoma fluid contained high concentrations of the PLN-A2PI complex (4.58 ± 2.60 µg/ml) and low concentrations of A2PI (10.32 ± 4.81 µg/ml), while both values in the plasma of 12 patients with chronic SDH's were within the normal range. This represents local hyperfibrinolytic activity in the hematoma.

Stuporous or comatose patients had higher PLN-A2PI complex levels than did the alert and the drowsy or disoriented patients. The layering type of hematoma as seen on computerized tomography scans showed the highest PLN-A2PI complex levels among five types of hematoma. In the fluid drained postoperatively from the subdural cavities of chronic SDH's, both the PLN-A2PI complex and A2PI levels decreased gradually in healing cases. In two patients with hematoma reaccumulation after surgery, both levels increased. The postoperative increase of the PLN-A2PI complex represents the recurrence of intermittent cycles of fibrinolysis, bleeding, coagulation, and hemostasis in the subdural space.

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Cerebral gumma

Case report

Wen-Zern Hwang, Takeshi Hasegawa, Haruhide Ito, Takashi Shimoji and Shinjiro Yamamoto

✓ A case of focal cerebral syphilitic gumma of the right temporal lobe is reported. Angiography showed moderate focal hypervascularity with stretched vessels, and irregularity of the vessel walls. Plain computerized tomography revealed an area of low density that enhanced strongly after intravenous administration of contrast medium.

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Isabel Fernández-Conejero and Vedran Deletis

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Eiji Ito, Masahiro Ichikawa, Takeshi Itakura, Hitoshi Ando, Yuka Matsumoto, Keiko Oda, Taku Sato, Tadashi Watanabe, Jun Sakuma and Kiyoshi Saito

Object

Dysphasia is one of the most serious complications of skull base surgeries and results from damage to the brainstem and/or cranial nerves involved in swallowing. Here, the authors propose a method to monitor the function of the vagus nerve using endotracheal tube surface electrodes and transcranial electrical stimulation during skull base surgeries.

Methods

Fifteen patients with skull base or brainstem tumors were enrolled. The authors used surface electrodes of an endotracheal tube to record compound electromyographic responses from the vocalis muscle. Motor neurons were stimulated using corkscrew electrodes placed subdermally on the scalp at C3 and C4. During surgery, the operator received a warning when the amplitude of the vagal motor evoked potential (MEP) decreased to less than 50% of the control level. After surgery, swallowing function was assessed clinically using grading criteria.

Results

In 5 patients, vagal MEP amplitude permanently deteriorated to less than 50% of the control level on the right side when meningiomas were dissected from the pons or basilar artery, or when a schwannoma was dissected from the vagal rootlets. These 5 patients had postoperative dysphagia. At 4 weeks after surgery, 2 patients still had dysphagia. In 2 patients, vagal MEPs of one side transiently disappeared when the tumors were dissected from the brainstem or the vagal rootlets. After surgery, both patients had dysphagia, which recovered in 4 weeks. In 7 patients, MEP amplitude was consistent, maintaining more than 50% of the control level throughout the operative procedures. After surgery all 7 patients were neurologically intact with normal swallowing function.

Conclusions

Vagal MEP monitoring with transcranial electrical stimulation and endotracheal tube electrode recording was a safe and effective method to provide continuous real-time information on the integrity of both the supranuclear and infranuclear vagal pathway. This method is useful to prevent intraoperative injury of the brainstem corticobulbar tract or the vagal rootlets and to avoid the postoperative dysphagia that is often associated with brainstem or skull base surgeries.

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Oral Presentations

2010 AANS Annual Meeting Philadelphia, Pennsylvania May 1–5, 2010