Historically, it has been reported that the insula drains primarily via the deep middle cerebral vein (DMCV). We found more complex (typically both superficial and deep) venous connections. In most specimens, the DMCV exhibited a direct venous connection to only a portion of the insular cortex. The deep drainage connections of the insula and the vessels that form the DMCV suggest that the DMCV drains primarily the lateral lenticular veins and secondarily the insula. Arterial contributions to the insula tended to be centered around the central insular sulcus, independent of the location of the middle cerebral artery bifurcation. Although the insular vascular anatomic features showed great variability, the anatomic and structural relationships described in this dissection series should facilitate safe surgical and endovascular interventions.

A modification of the supraorbital keyhole approach, the eyebrow incision-minisupraorbital craniotomy with orbital osteotomy, is described. Unique to this approach is a one-piece supraorbital craniotomy, measuring 2.5 x 3.5 cm, that incorporates the orbital rim and roof and the frontal process of the zygomatic bone through an eyebrow incision. The orbital osteotomy facilitates view of the anterior and middle cranial fossa through the operating microscope, as well as the maneuverability of instruments through a small craniotomy. A pericranial flap is elevated with its base at the orbit and used for closure of the frontal sinus, if necessary. The approach was used successfully in elective surgery of 10 aneurysms of the anterior circulation. The mean aneurysm size was 5.9 mm, with a range of 4 to 10 mm. Advantages of this approach include minimal disruption and exposure of normal brain tissue, reduced frontal lobe retraction, and an excellent postoperative cosmetic result. The approach is performed quickly by virtue of a limited skin incision with minimal temporalis muscle dissection and a small bone flap. The neuroendoscope, although helpful at times, is not essential and no special instruments or intraoperative image guidance is required. Relative contraindications include the presence of a large frontal sinus, severe brain edema, and recent subarachnoid hemorrhage. In addition, this approach has not been used for the treatment of giant intracranial aneurysms.

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Use of ETV in adult hydrocephalus has broad application with a low complication rate and reasonably good efficacy in selected patients.

Knowledge of the distribution of the perforating branches along the proximal middle cerebral artery and at the internal carotid artery bifurcation is important for the surgeon approaching aneurysms and other lesions in these areas. The microsurgical anatomy of the proximal middle cerebral artery and the internal carotid artery bifurcation was analyzed in 36 fixed hemispheres. The number, size, and location of all perforators along the proximal middle cerebral artery and the internal carotid artery bifurcation were noted. Three distinct patterns of perforators arising from the proximal middle cerebral artery were found. The implications of the anatomical variations in this area are discussed.