Michiari Kawamo

Showa University, Shinagawa, Tōkyō, Japan

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Publications (5)3.95 Total impact

  • Brain and nerve = Shinkei kenkyū no shinpo 05/2012; 64(5):570-1.
  • Brain and nerve = Shinkei kenkyū no shinpo 10/2011; 63(10):1136-7.
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    ABSTRACT: Cerebrospinal fluid (CSF) shunts are frequently used to treat hydrocephalus. The use of a programmable shunt valve allows physicians to easily change the opening pressure. Since patients with adjustable CSF shunt valves may use portable game machines, the permanent magnets in these machines may alter the shunt valve programmed settings or permanently damage the device. This study investigated the risk of unintentional valve adjustment associated with the use of game machines in patients with programmable CSF shunt valves. Four adjustable valves from 4 different manufacturers, Sophysa Polaris model SPV (Polaris valve), Miethke proGAV (proGAV), Codman Hakim programmable valve (CHPV), and Strata II small valve (Strata valve), were evaluated. Magnetic field interactions were determined using the portable game machine, Nintendo DS Lite (DS). The maximum distance between the valve and the DS that affected the valve pressure setting was measured by x-ray cinematography. The Polaris valve and proGAV were immune to unintentional reprogramming by the DS. However, the settings of the CHPV and Strata valves were randomly altered by the DS. Patients with an implanted shunt valve should be made aware of the risks posed by the magnetic fields associated with portable game machines and commonly used home electronics.
    Neurologia medico-chirurgica 01/2011; 51(9):635-8. · 0.49 Impact Factor
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    ABSTRACT: Rathke's cleft cysts are often difficult to differentiate from other sellar cystic lesions using conventional MR imaging. The purpose of this study was to investigate the usefulness of single-shot fast spin-echo (SSFSE) diffusion-weighted MR imaging (DWI) in the diagnosis of a Rathke's cleft cyst. We examined retrospectively 29 patients with a histologically verified sellar or suprasellar lesion containing a fluid component; 12 patients had a Rathke's cleft cyst, 6 patients a craniopharyngioma, 5 patients a haemorrhagic pituitary adenoma, and 6 patients a cystic pituitary adenoma). Several regions of interest (ROIs) for apparent diffusion coefficient (ADC) measurements were identified in the fluid components of the lesions. For comparison, ADC values were normalized using a relative ADC (rADC), which was determined by dividing the ADC values of lesions by those of normal white matter and expressing the quotient as a ratio. SSFSE provides diffusion-weighted images without significant susceptibility artifacts. DWI-SSFSE revealed Rathke's cleft cysts as hypointense relative to the normal brain parenchyma in all cases. The mean value of ADC for Rathke's cleft cysts was 2.12 x 10(-3) mm(2)/sec. Both the ADC and relative ADC of the Rathke's cleft cysts were significantly increased compared to those of the cystic components of craniopharyngiomas and haemorrhagic components of pituitary adenomas in the subacute phase (P < 0.05). There was not a statistically significant difference between Rathke's cleft cysts and cystic components of pituitary adenomas (P < 0.05). DWI-SSFSE with ADC values provides objective information in the differential diagnosis of Rathke's cleft cysts from other sellar cystic lesions. In addition, DWI-SSFSE with ADC values is useful for differentiating Rathke's cleft cysts from craniopharyngiomas and haemorrhagic pituitary adenomas.
    Acta Neurochirurgica 08/2007; 149(8):759-69; discussion 769. · 1.79 Impact Factor
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    ABSTRACT: Post operative scar tissue makes transsphenoidal surgery for recurrent pituitary lesions very difficult. However, with the use of a new cautery system, known as the EMF system, we were able to perform the surgical procedures with relative ease. In this article, we report the advantages and clinical applications of this new instrument in transnasal reoperation. The EMF system generates a high frequency current of 13.56 MHz that is focused on the target. This enables it to coagulate, cut, and vaporize tissue in a pinpoint fashion. The bayonet and pencil-type hand pieces of the EMF system are slim, and the tips of the probe are flexible. This enables the surgeon to easily reach deep narrow spaces. We have used the EMF system for transsphenoidal surgery on recurrent pituitary lesions in 18 patients. The system was used to cut and vaporize scar tissue and vaporize firm and fibrotic tumor tissue. During surgery, the system could easily cut and vaporize scarred tissues in the nasal cavity, the sphenoid sinus, and the sella, without damage to the surrounding tissue. In addition, in 3 patients who had extremely fibrotic and firm tumors, we were able to easily vaporize the tumor with safety. The EMF system enables the surgeon to cut and vaporize tissue with ease and with minimal injury to the surrounding structures. It was particularly valuable in the resection of firm tumors. It may also shorten the operating time because of quick vaporization of the firm tissue.
    Surgical Neurology 02/2007; 67(1):40-4; discussion 44-5. · 1.67 Impact Factor