Objective : The International Study of Unruptured Intracranial Aneurysms (ISUIA) reported that the 5-year cumulative rupture rate of small unruptured aneurysms less than 7 mm in diameter is very low depending on the aneurysm's location. However, we have seen a large number of ruptured aneurysms less than 7 mm in clinical practice. The purpose of this study was to review our experience and to measure the size and location at which aneurysms ruptured in our patient population. Methods : We reviewed the characteristics of aneurysms, such as size and location, from the original angiograms of patients who were admitted to our hospital between January 2004 and December 2007. All aneurysms were treated surgically or through endovascular procedures. Results : Interventional or surgical treatment was given to a total of 889 patients, including 568 females and 321 males. At the time of our study, 627 cases were ruptured aneurysms and 262 cases were unruptured aneurysms. Of the ruptured cases, the mean diameter of the aneurysm was 6.28 mm. We found that 71.8% of ruptured aneurysms were smaller than 7 mm in diameter, and 87.9%, were smaller than 10 mm. Based on location, the data show that anterior communicating artery aneurysms most often presented with rupture sizes less than 7 mm (76.8%) and 10 mm (92.1%) in diameter. Most ruptured aneurysms were less than 7 mm in size, although recent studies have noted that small aneurysms are less likely to rupture. Conclusion : Although the natural history of unruptured intracranial aneurysms remains controversial, the aneurysm size and location play a signigicant role in determining the risk of rupture. Larger sample sizes and a long term study are needed to reveal the natural history and the rupture risk of unruptured intracranial aneurysms because the size of most ruptured aneurysms was less than 7 mm in diameter in our series.

J Korean Neurosurg Soc 46 : 152-155, 2009A 43-year-old woman presented with dizziness, ataxia and right hearing difficulty. Her magnetic resonance images demonstrated an inhomogeneously contrast-enhanced large tumor growing into right cavernous sinus and Meckel's cave located totally within intradural retroclival region. She underwent retromastoid suboccipital craniotomy to resect the tumor mass and adjuvant gamma knife radiosurgery for remnant tumor at 1 month after operation. Adjuvant radiosurgery after surgical excision seems to be effective for the treatment of intradural extraosseous chordomas.

The nature of high specific strength compared with other structural materials has led to wide application of Mg alloys. However, Mg alloys often exhibit relatively low strength and/or low surface stability, which can limit the practical application of the alloy system. In order to achieve high strength, the commercial AZ61 alloys were extruded, so that the application of the alloy system can be extended towards new structural parts for requiring the light nature of the alloy system. In this study, a high temperature extrusion has been carried out for the commercial Mg alloys (AZ61). The productivity and mechanical properties of the alloy were critically affected by the extrusion conditions such as temperature, extrusion ratio and extrusion speed. The texture development and alloy strengths with respect to the extrusion conditions have been discussed in terms of microstructural observations and phase analyses.

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