Anatomy of the sphenopalatine artery and its implications for transnasal neurosurgery.

BACKGROUND: The knowledge of sinonasal vasculature is inevitable in transnasal neurosurgery. We performed an anatomical study on the sphenopalatine artery from the perspective of skull base procedures. METHODOLOGY: To analyse the anatomical landmarks of the sphenopalatine artery, arterial skull corrosion casts (26 head halves) underwent endoscopic transnasal phantom surgery. Furthermore, we performed microsurgical dissection on formaldehyde-fixated cadavers with arterial perfusion (14 head halves) as well as studied Cone Beam CT-scans of anonymised patients and cadavers (115 head sides). RESULTS: In our cadaveric material, the sphenopalatine foramen is located at the transition of the superior and middle nasal meatus (95.0%) or in the superior nasal meatus (5.0%). It is the main entry point of the branches of the sphenopalatine artery into the nasal cavity. In most cadaveric cases (25.0%), at this level there are 2 branches superiorly and 1 vessel inferiorly to the ethmoid crest. An average of 2.4 vessels leave the sphenopalatine foramen superiorly to the ethmoid crest, 97.8% of them belong to the sphenopalatine arterys posterior septal branches. An average of 2.1 branches leave the sphenopalatine foramen inferiorly to the ethmoid crest; all of them belong to the posterior lateral nasal branches. There are no cases with a single artery at the plane of the sphenopalatine foramen. We describe a triangular bony structure bordering the sphenopalatine foramen anteriorly which is built up by the palatine and ethmoid bone as well as the maxilla. According to the radiographic studies, this triangular prominence is surrounded superiorly by a posterior ethmoid cell (57.4%), the sphenoid sinus (41.7%) or the orbit (0.9%) with a varying contribution of the superior nasal meatus; inferolaterally by the maxillary sinus (98.3%) or the pterygopalatine and infratemporal fossa (1.7%) and inferomedially by the middle nasal meatus. The medial vertex of the bony triangle corresponds to the ethmoid crest of the palatine bone. In transnasal endoscopic surgery, the posterior lateral nasal branches of the sphenopalatine artery appear at the triangle's inferomedial edge, the posterior septal branches emerge at its superior edge. CONCLUSIONS: The triangular bony structure is a landmark to find and differentiate the posterior lateral nasal and posterior septal branches of the sphenopalatine artery and to identify the sphenoid sinus.

The minimally invasive supraorbital subfrontal key-hole approach for surgical treatment of temporomesial lesions of the dominant hemisphere.

INTRODUCTION: Surgery in the temporomesial region is generally performed using a subtemporal, transtemporal, or pterional-transsylvian approach. However, these approaches may lead to approach-related trauma of the temporal lobe and frontotemporal operculum with subsequent postoperative neurological deficits. Iatrogenic traumatisation is especially significant if surgery is performed in the dominant hemisphere. METHODS: During a five-year period between January 2003 and December 2007, we have approached the temporomesial region in 21 cases via the supraorbital approach. In 15 cases, the lesion was located within the dominant hemisphere, all lesions had space-occupying effects. In all cases, meticulous approach planning was performed, demonstrating a close proximity of the lesion to the pial surface on the upper anterior mesial aspect of the temporal lobe. An extension within the parahippocampal gyrus or with deep temporobasal tumor growth below the sphenoid wing were considered as exclusion criteria for using the supraorbital approach. RESULTS: In all cases surgery was performed without intraoperative complications. Pathological investigation showed 7 low-grade astrocytomas, 4 high-grade astrocytomas, 2 gangliogliomas and 2 cavernomas. Early postoperative MRI scans confirmed a complete removal of the lesion in 14 cases. In one case of a subtotal resection, the residual tumor was removed through a posterior subtemporal approach. The postoperative neurological examination was unchanged in 14 cases. In one case a transient hemiparesis was observed. In patients with dominant-sided lesions no speech or mental deficits were present. CONCLUSION: In selected cases, the minimally invasive supraorbital craniotomy offers excellent surgical efficiency in the temporomesial region with no approach-related morbidity compared to a standard transtemporal or pterional-transsylvian approach.

Endoscope-assisted microsurgery for tumors of the septum pellucidum: surgical considerations and benefits of the method in the treatment of four serial cases.

Neoplasms that primarily originate from the septum pellucidum are extremely rare. Generally the septum pellucidum is involved in direct extension of tumors that arise from the neighboring structures, principally the corpus callosum. Endoscope-assisted techniques form a useful adjunct to common microsurgical procedures to completely remove intraventricular lesions. There are two main advantages of endoscope-assisted surgery over common microsurgical techniques: reduction of superficial brain retraction with less iatrogenic trauma to the neighboring structures and inspection of hidden corners depict simultaneously anatomical details which are not precisely visible in the zoomed and thus light-reduced beam of the microscope. Four patients with septum pellucidum tumors underwent surgery by a transcallosal approach. In all four patients the endoscope-assisted microsurgery technique was used to remove the tumor. In one of the four patients neuronavigation was additionally used for guidance. Complete tumor excision was achieved in all patients. The histological findings showed pilocytic astrocytoma in two cases, one subependymoma and one neurocytoma, respectively. There were no postoperative complications. Endoscope-assisted microsurgery provides maximum efficiency to remove the septum pellucidum tumors with minimum invasiveness.