Removal of anterior clinoid process for basilar tip aneurysm: clinical and cadaveric analysis.

The difficulty in the operation for basilar tip aneurysm is the restriction in surgical working space. To resolve this problem, aggressive skull base surgery has been reported, but these techniques are not prevalent. Pterional and subtemporal approaches are commonly used for basilar tip aneurysms. In an attempt to increase the surgical working space during the pterional approach, the anterior clinoid process and the roof of the optic nerve were removed extradurally to increase the mobilization of the intracranial internal carotid artery and optic nerve. The effects of removing the anterior clinoid process and microanatomy in the perioptic area were analyzed by cadaveric procedures in 10 cases (20 sides). With this procedure, the internal carotid artery can be retracted medially with a spatula 6.1 +/- 0.8 mm (mean +/- SD). The length and the area of dural fold in the bone defect region in the optic canal roof are 2.1 mm and 13.6 mm. In 10 clinical cases, this procedure allowed enough space to approach the basilar tip aneurysm without disturbing the internal carotid artery blood flow. The clinical outcome was satisfactory.

Method to improve cosmetic outcome following craniotomy.

This technical note describes a simple method for reducing the dead space created by craniotome due to the loss of bone dust and improving the cosmetic outcome following a craniotomy. After drilling the burr holes for the craniotomy, the bone between the holes is drilled away in a standard fashion except that multiple regions of about 1 cm in length are left intact. These intact regions are broken using a periosteal elevator and fixed like a bridge when the bone is replaced. The resulting bone flap is readily returned to its original position without making the dead space created by regular craniotomy. The amount of the dead space caused by losing the bone dust is reduced and a good cosmetic recovery is obtained. This technique is useful for both craniotomy and facial bone surgery, which requires cosmetic results.

Enlarged entry space for the transpetrosal approach.

This report describes the removal of the roof of the external auditory meatus in approaching the tentorial edge, the cerebropontine angle, hippocampal brainstem lesions, and upper clival lesions. This procedure not only provides more space in approaching the tentorial edge or upper brainstem, it also provides a wider entry space for approaching posterior fossa lesions. This approach is also for lesions located lower than the tentorium or in the upper clivus. There is still some confusion about the method for removing the roof of the external auditory canal. We describe the clinical experience and comprehensive surgical procedures used on cadavers. Our extended temporal craniotomy technique using the removal of the roof of the external auditory meatus is a simple, safe, and useful method for obtaining a wider entry space to approach deep perimesencephalic lesions and the posterior fossa.

Expression of water channel mRNA following cerebral ischemia.

Water channel is a protein which regulates transcellular water permeability. Among mRNA expression of six principal mammalian water channels, AQ4 mRNA expression was highest in the brain. Water channels are supposed to regulate cerebral edema but the detailed physiological and pathological function is unknown. Brain edema has been analyzed as an aspect of ion channel injury or membrane injury. However the transportation of water molecule itself following cerebral ischemia is unknown. As water channels transport only water molecules, the functional changes of water channels following cerebral ischemia are of great interest. To evaluate the role of water channels in cerebral edema following cerebral ischemia, the changes of water channel mRNA expression were evaluated. Cerebral edema was induced by suture method. The extraction of water channel mRNA was performed according to Chomczynsli and Sacchi. RT-PCR was applied to extracted mRNA. Water channel mRNA electrophoresis was performed. For semi-quantified evaluation of water channel, mRNA intensities of the infarct hemisphere and normal hemisphere were compared. The expression of water channel mRNA was decreased following cerebral ischemia. This damage leads to loose physiological control of water permeability of the cell membrane in the neuron, glia and endothelial cells which leads to brain edema.