The authors review their experience in the surgery of intracranial aneurysms via an eyebrow keyhole approach. The eyebrow keyhole approach presumes a skin incision in the lateral two-thirds of the eyebrow followed by small supraorbital craniotomy (15 x 25 mm). Using this approach and an intraoperative endoscope for better visualisation of the aneurysmal neck, the authors operated on thirty-seven patients with forty intracranial aneurysms. There was no mortality, postoperative recovery was fast, and the cosmetic effect was excellent. Advantages and possibilities of this approach are discussed and results are presented. The authors recommend this approach as a minimal invasive surgery procedure in the treatment of intracranial aneurysms. When performed by experienced vascular neurosurgeons this approach is neither more difficult for the surgeon nor more dangerous for the patient than any other standard craniotomy procedure. According to the authors' present results, surgery of intracranial aneurysm via an eyebrow keyhole approach is the method of choice when performed by an experienced vascular neurosurgeon.

The authors describe their first clinical experiences in endoscopic third ventriculostomy (ETV) with the original ultrasonic contact microprobe (UCM) designed at the Department of Neurosurgery in Zagreb. The analysis includes the clinical course of disease in eight patients submitted to surgery from May to September 1999 (3 men and 5 women, from 14 to 61 years of age). Surgery was performed in patients with neurological symptoms of elevated intracranial pressure and neuroradiological evidence of non-communicating hydrocephalus caused by mesencephalic aqueduct stenosis. The perforation in the base of the third brain ventricle made by the ultrasonic contact microprobe was widened by a balloon catheter. The authors have come to conclusion that the ETV when performed by contact ultrasonic microprobe is a small risk procedure in case of non-communicating hydrocephalus. For its small diameter (1.6 mm) and simple handling the newly designed contact ultrasonic microprobe is very suitable for use in neuroendoscopy as it enables fenestration of the third brain ventricle with minimal thermal and ultrastructural damage to the adjacent neurovascular structures. Further research will be focused on defining indications for the use of the device in other neuroendoscopic procedures as well.

Cavernous angioma of the optic chiasm or optic nerve is extremely rare. We report the case of a 58-year-old woman with cavernous angioma of the optic chiasm. The lesion was totally removed through the eyebrow keyhole approach, which allowed appropriate intraoperative exploration of the optic chiasm and related structures. The present case confirms that a cavernous angioma located in the optic chiasm can be totally resected without further impairment of visual function.

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At the Department of Neurosurgery, School of Medicine, University of Zagreb, the original ultrasonic contact microprobe (UCM) was designed. The efficacy of the instrument was tested on 120 brains of Wistar strain rats. The authors have been investigating the possibility of transferring high-energy ultrasound through the titanium wire probe of the device and the efficacy of UCM in controlled punctiform destruction of brain tissue. Light and electron microscope assessed the lesions made in the brains of experimental rats. Histological findings in the preparations showed the zone of thermal injuries from 100 to 200 microm and the zone of ultrastructural changes from 200 to 300 microm, indicating the sparing effect of the microprobe with regard to the adjacent neurovascular structures. The small dimensions of the ultrasonic contact microprobe (1.6 mm) enable its introduction through the operating canal of a ventriculoscope. Further research is expected to show the efficacy of the ultrasonic contact microprobe in endoscopic neurosurgery.