Microsurgical Management of the Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Feasibility Study

Background: The proper head positioning decreases the surgical complications by enabling a better surgical maneuverability. Middle cerebral artery (MCA) bifurcation aneurysms have been classified by Dashti et al. [Surg Neurol. 2007 May;67(5):441–56] as the intertruncal, inferior, lateral, insular, and complex types based on dome projection. Our aim was to identify the optimum head positions and to explain the anatomic variables, which may affect the surgical strategy of MCA bifurcation aneurysms. Methods: The lateral supraorbital approach bilaterally was performed in the 4 cadaveric heads. All steps of the dissection were recorded using digital camera. Results: The distal Sylvian fissure (SF) dissection may be preferred for insular type and the proximal SF dissection may be preferred for all other types. Fifteen degrees head rotation was found as the most suitable position for the intertruncal, lateral type and subtype of complex aneurysms related with superior trunk. Thirty degrees head rotation was found the most suitable position for the inferior type, insular type, and subtype of complex aneurysms related with inferior trunk. Conclusions: The head positioning in middle cerebral bifurcation aneurysms surgery is a critical step. It should be tailored according to the projection and its relationship with the parent vessels of the middle cerebral bifurcation.

Adult Nasoethmoidal Encephalocele Corrected by Supraorbitary Approach: Case Report and Review

Encephalocele is a protrusion of the central nervous system elements through a defect in the dura mater and in the cranium. The prevalence of encephalocele ranges from 0.08 to 0.5 per 1,000 births. The posterior encephaloceles are more common in North America and Europe, while frontal defect is frequently found in Asia. The present paper describes a 26-year-old male patient presenting with cerebrospinal fluid leak and meningitis symptoms. He was diagnosed with congenital nasoethmoidal encephalocele and treated surgically using a supraorbital approach without complications.

Transcranial Approaches to the Orbit

Transcranial approaches to the orbit provide familiar and flexible approaches with wide access to the majority of the orbit, only limited in the inferomedial orbit. A pterional craniotomy is the predominant approach but can be expanded with an orbital or zygomatic osteotomy for even wider access. Minimally invasive approaches, such as the lateral supraorbital or “eyebrow” supraorbital approach, are options for selected pathologies and minimize morbidity related to the approach.

Comparative anatomical analysis between the minipterional and supraorbital approaches

OBJECTIVEKeyhole approaches, namely the minipterional approach (MPTa) and the supraorbital approach (SOa), are alternatives to the standard pterional approach to treat lesions located in the anterior and middle cranial fossae. Despite their increasing popularity and acceptance, the indications and limitations of these approaches require further assessment. The purpose of the present study was to determine the differences in the area of surgical exposure and surgical maneuverability provided by the MPTa and SOa.METHODSThe areas of surgical exposure afforded by the MPTa and SOa were analyzed in 12 sides of cadaver heads by using a microscope and a neuronavigation system. The area of exposure of the region of interest and surgical freedom (maneuverability) of each approach were calculated.RESULTSThe area of exposure was significantly larger in the MPTa than in the SOa (1250 ± 223 mm2 vs 939 ± 139 mm2, p = 0.002). The MPTa provided larger areas of exposure in the ipsilateral and midline compartments, whereas there was no significant difference in the area of exposure in the contralateral compartment. All targets in the anterior circulation had significantly larger areas of surgical freedom when treated via the MPTa versus the SOa.CONCLUSIONSThe MPTa provides greater surgical exposure and better maneuverability than that offered by the SOa. The SOa may be advantageous as a direct corridor for treating lesions located in the contralateral side or in the anterior cranial fossa, but the surgical exposure provided in the midline region is inferior to that exposed by the MPTa.