Unilateral Approaches To Bilutateral Cerebral Aneurysms: A Study Of Microsurgical Anatomical

Among patients diagnosed with cerebral aneurysms, It was reported that the incidence of multiple intracranial aneurysms is between 14% and 34% .In approximately 20% to 40% of these patients with the aneurysms are bilateral . If the multiple intracranial anurysms on the bilateral intracarotid arteries in the supratentorial were adequately and safely exposed and clipped by a single unilateral approach craniotomy carried out for being would simplify treatment beacause it would avoid encounter second operation, which would play an important role in not only decreacing mortality ,increacing curative ratio,but also lightening economic burden for patiens in the clinic. We conducted a microsurgical study in humen cadaver heads to investigate the feasibility of surgical clipping of all bilateral supratentorial multiple aneurysms via a umlalateral approach and some important morphometric data were documented for anatomical parameter for neurosurgical practise in the clinic.In this study, pteroinal approach craniotomies were performed in 15 adult cadaveric heads, which had been fixed in formalin. We conducted a microsurgical study in human cadaver specimens with the aid of an operating microscope, to examine the bilateal exposure multiple aneurysms at the most common five sites in the anterior circulation, such as the origin of the ophthalmic artery(OA), The origin of the posterior communicating artery(PCOA), The internal carotid artery ( ICA ) termination, The anteriorcommunicating artery (ACOA) complex, And the middle cerebral artery (MCA) bifurcation. We have attempted to choose the best surgical approach and to establish guidelines for the microsurgical exposure of aneurysms at these sites based on morphometric data obtained in our study for colleagues reference in the clinic.Our study showed the following: 1) The origin of contralateral OA was successfully exposed in 63.3% of specimens. Theoptimum corridor for visualization of this vessel was always the anterior opticochiasmatic space below the bilateral opitic nerves. Exposure was optimized by incision of the falciform dural fold and partial mobilizatiom of the contralateral optic nerve . 2) The contralateral origin of PCOA was successfully exposed in 50% of specimens. The corridor for visualization of the contralateral PCOA usually ran through the anterior opticochiasmatic space, Occasionally requiring incision of the falciform dural ligament and mobilization of the contralateral optic nerve. In some specimens however, the origin of PCOA was adequately exposed through the opticocarotid corridor, superior and lateral to the optic chiasm. 3) The contralateral ICA termination was successfully exposed in 100% of specimens. Visualization of the distal ICA and proximal AI and M] segments was achieved with only gentle retractionof the frontal lobes. 4) The ACOA complex is a midline structure. It is equally accessible from either side. 5 ) The contralateral MCA bifurcation was succfully exposed in 60% of specimens. The contralateral MCA bifurcation was visualized only when the MI segments less than 14mm in length. Progressive opening of the contralateral sylvian cistern and frontal lobe retraction then led to exposure of the contralateral MCAbifurcation . In this study, Morphometric date, including surgical space, lengths and diameters of major arterial segments and nerves, were documented, and implications for the contralateral approach to aneursysms at this site are discussed.