Indocyanine green fluorescence visualizes landmark arteries for endoscopic sinus and skull base surgery.

OBJECTIVE: Landmark arteries during endoscopic sinus surgery are currently identified on the basis of anatomy, CT imaging and navigation, and Doppler flowmetry. However, the advantage of intraoperative fluorescence imaging during endoscopic sinus surgery has not been demonstrated. This study aimed to investigate whether Indocyanine Green (ICG) is useful for visualizing landmark arteries during endoscopic sinus and skull base surgery. METHODS: Eight patients who underwent endoscopic sinus and pituitary surgeries and consented to study participation were included. After planned procedures were performed as usual, landmark arteries were examined by ICG endoscope. Recorded video and preoperative CT images were analyzed for identification of five landmark arteries: anterior ethmoidal artery (AEA), posterior ethmoidal artery (PEA), internal carotid artery (ICA), sphenopalatine artery (SPA), and postnasal artery (PNA). Identification of arteries was evaluated three grades: identifiable, locatable, unrecognizable. RESULTS: Eight patients and eleven sides were evaluated. The ICG dose was 2.5 mg/body and a single shot was sufficient for evaluation. 100 % of AEA was identified (9/9 sides), 86 % of PNA (6/7 sides), 56 % of ICA (5/9 sides), and 25 % of PEA and SPA (2/8 sides). CONCLUSION: ICG could visualize landmark arteries, even thin arteries like AEA, during endoscopic sinus and skull base surgeries. Visualization was affected by thickness of bone or soft tissue above arteries, blood clots, sensitivity setting, and angle and distance of near-infrared light irradiation. ICG visualization of landmark arteries may help avoid vascular injuries during endoscopic sinus and skull base surgeries, particularly of AEA, PNA and ICA.

Endovascular treatment for dural arteriovenous fistulas in the petroclival region.

Petroclival region dural arteriovenous fistulas (DAVFs) are rare and difficult lesions to manage. They often have very complex anatomical structures and can be further divided into the superior petrosal sinus, petrous apex, inferior petrosal sinus, upper clival, and upper clival epidural-osseous DAVFs. Most petroclival region DAVFs should be treated due to their high Cognard grades. Currently, endovascular treatment (EVT) has become the first-line therapeutic option for petroclival region DAVFs. But not all the petroclival region DAVFs could be cured with EVT. When the arterial feeders are large or the DAVF is adjacent to the venous sinus, the success rate may be higher. In petroclival region DAVFs, if EVT can be performed successfully, satisfactory outcome can be anticipated. However, there are some inadvertent complications, which include cranial nerve palsy, subsequent sinus thrombosis, and migration embolization of the internal carotid artery and vertebral artery. Currently, a review of the EVT of petroclival region DAVFs is lacking. In this article, we performed a review of the relevant literature on this issue. In addition, some illustrative cases would be provided to elaborate these specific entities.

Radiologic analysis of the location, shape and size of the external aperture of the carotid canal in children.

OBJECTIVES: This retrospective computed tomography (CT) study was aimed to assess the growth dynamic of the external aperture of the carotid canal (EACC) in children aged between 1 and 20 years. METHODS: Two hundred patients (sex 100 females/100 males, average age 10.50 ± 5.77 years) with good head CT image quality were included in this study. CT images of the patients were used to obtain data related to the location, shape and dimension of EACC. RESULTS: EACC shapes were identified as oval shaped, round shaped, and tear-drop shaped in 58.3% (233 sides), 24% (96 sides) and 17.8% (71 sides), respectively. EACC length, disEACC-MSP (distance between EACC and midsagittal plane), and EACC width did not change from the prepubescence period; while, the disEACC-SC (distance between EACC and supramastoid crest) seemed to reach adult size in the postpubescence period. Linear functions for EACC length and width were calculated as: y = 5.453 + 0.091 × years, and y = 5.398 + 0.059 × years, respectively. CONCLUSION: The regression equations of the measured parameters representing the growth dynamic of EACC in children can be helpful to estimate its size, location and angulation, which suggest that the dimension and distances to certain anatomical landmarks seemed to reach adult size in different developmental periods. In this context, the findings of this study may seem to emphasize the importance of preoperative radiological evaluation on skull base, related to EACC, for multidisciplinary surgeon teams during childhood surgeries in terms of patients' positioning, and the selection of appropriate surgical approach.

An undescribed venous pathway intervening between the olfactory fossa and nasal vestibule.

PURPOSE: A curvilinear pathway intervening between the olfactory fossa and nasal vestibule has not been well documented. Therefore, the aim of this study was to examine its structure using magnetic resonance imaging (MRI). METHODS: In total, 84 patients underwent thin-sliced, contrast MRI. Among these patients, 31 underwent additional thin-sliced, sagittal T2-weighted imaging. RESULTS: A curvilinear pathway intervening between the olfactory fossa and nasal vestibule was delineated on sagittal and coronal imaging in 98% and 82% of patients, respectively. All of these pathways demonstrated communication with the lower limit of the superior sagittal sinus (SSS) or fine venous channels connecting to the SSS in the vicinity of the crista galli. The pathway was identified in the parasagittal regions on both sides with varying lengths, diameters, and curvatures. In 94% of the patients who underwent sagittal T2-weighted imaging, the pathways appeared as linear high-intensity signals. Most pathways were delineated as a single channel coursing extracranially adjacent to the olfactory fossa. In 38% of the patients, post-contrast sagittal images showed variable filling defects between the olfactory bulb and floor of the olfactory fossa, furthermore traversing the venous pathway. Additionally, in 73% of the patients, post-contrast images identified diploic venous channels, variably in the nasal bone and communicating with the venous pathway. CONCLUSIONS: A curvilinear pathway intervening between the olfactory fossa and nasal vestibule is a consistent venous structure and may function as an extracranial route of cerebrospinal fluid drainage.

Diploic veins of the cranial base: an anatomical study using magnetic resonance imaging.

PURPOSE: The anatomy and distribution of the diploic veins (DVs) of the cranial base have not been fully documented. The aim of this study was to characterize these veins using contrast magnetic resonance imaging (MRI). METHODS: In total, 95 patients underwent thin-sliced, contrast MRI. Coronal and sagittal images were used for the analysis. The cranial base was divided into the anterior, middle, and posterior bases. Then, each base was further subdivided into three equal parts in the anteroposterior and lateromedial directions. The anteroposterior parts were evaluated on coronal images, while the lateromedial parts were evaluated on sagittal images. RESULTS: The DVs were identified over the entire cranial base. However, they were more frequent in the posterior-third of the lateral-third region of the anterior, middle-third of the lateral and middle-third regions of the middle, and middle-third region of the posterior cranial base, and sparse in the posterior and medial-third regions of the middle cranial base. The DVs showed marked morphological variability. For instance, the DVs of the pterional area were generally well defined, as pivotal channels connecting the lateral parts of the anterior and middle cranial base, but were highly varied in appearance. CONCLUSIONS: The DVs of the cranial base are distinct structures characterized by morphological variability and topographical predilection. Contrast MRI is useful for delineating these veins.

Anatomical variations of anterior ethmoidal artery at the ethmoidal roof and anterior skull base in Asians.

PURPOSE: The variations of the anterior ethmoidal artery (AEA) in different populations should be recognized by surgeons to prevent unwarranted complications during surgery. The aim of this study was to assess the anatomical variations of AEA in Asian population. METHODS: A cross-sectional study of 252 AEA identified by computed tomography (CT) of the paranasal sinuses. The multiplanar CT images were acquired from SOMATOM® Definition AS+ and reconstructed to axial, coronal and sagittal view at 1 mm slice thickness. RESULTS: 42.5% of AEA was within skull base (grade I), 20.2% at skull base (grade II) and 37.3% coursed freely below skull base (grade III). The prevalence of supraorbital ethmoid cell (SOEC) and suprabullar cell (SBC) was 29.8% and 48.0%. The position of AEA at skull base has significant association with SOEC (p < 0.001), but not with SBC (p = 0.268). Type I Keros was 42.1% and Type 11 Keros was 57.9%. When lateral lamella's height is longer, the probability increases for AEA to course freely within the ethmoid sinus (p = 0.016). The mean distance of AEA from skull base was 1.93 ± 2.03 mm, orbital floor 21.91 ± 2.47 mm and nasal floor 49.01 ± 3.53 mm. CONCLUSIONS: The position of AEA at skull base depends on the presence of SOEC and length of lateral lamella, but not with SBC. When compared to European population, the mean distance between AEA and nasal floor is shorter in Asians.

[Variability and age-related features of the anatomy of the midline structures of the anterior skull base]. / Variabel'nost' i vozrastnye osobennosti anatomii sredinnykh struktur perednikh otdelov osnovaniia cherepa.

The article presents the literature data on the structural variability and age-related features of the midline anatomical structures of the anterior skull base (frontal sinus, ethmoid bone, anterior parasellar region, and medial orbital wall). This is the area of surgical interests of neurosurgeons and rhinosurgeons. The study objective is to analyze the literature data on the individual variability and age-related anatomy of these structures. The work is illustrated with original images from the authors' personal archive. The individual anatomical features of eloquent structures in the surgical area (structures within the surgical corridor, key anatomical landmarks, optic tract, internal carotid and ethmoidal arteries, etc.) should be considered in planning surgery in patients of all age groups because they can limit the view and the amount of safe manipulations or increase the risk of complications. The presented data may be useful for neurosurgeons and otolaryngologists whose surgical interests are focused on the midline structures of the anterior skull base.

Contrast-enhanced Reformatted MR Images for Preoperative Assessment of the Bridging Veins of the Skull Base.

Magnetic resonance (MR) venography and computed tomographic (CT) venography are suited for displaying the convexity veins that drain the medial and lateral surfaces of the brain hemispheres. However, such is not the case for the bridging veins of the skull base. Technical factors prevent contrast material-enhanced MR or CT images obtained in standard axial, coronal, and sagittal planes from fully displaying the curved pathways of these clinically important venous structures. This limitation can be overcome by using a reconstruction technique that depicts these venous structures and their interconnections. Curved and multiplanar reformatted images that distill the important venous features often require knowledgeable manipulation of source images by an operator who is familiar with numerous venous variants and their surgical implications. The normal anatomy of the draining veins is detailed-anatomy that radiologists must master before they can show the surgeon the important venous anatomy that is often missing at standard imaging; this information will foster better communication between radiologists and their surgical colleagues. As a practical matter, the skull base veins are arbitrarily subdivided into those that are at greatest risk with the pterional approach and the subtemporal approach, respectively. These approaches can be expanded to define connections between the superficial venous system and the other valveless venous networks that drain the deep portions of the cerebral hemisphere, the scalp, face, muscles of the neck, diploë of the skull, and meninges. As radiologists gain experience, their image interpretations should mature beyond simple analysis of the primary hemodynamic changes induced by intraoperative sacrifice or injury.

Diagnostic limitations in the treatment of cerebral aneurysms.

BACKGROUND: Endovascular coiling has become a standard technique in the treatment of cerebral aneurysms. The mechanisms of recurrence are incompletely understood. METHODS: In our clinical investigations we present three uncommon cases where the pathology at the base might has been underestimated in digital subtraction or magnetic resonance angiography. RESULTS: In the first clinical study rehemorrhage occurred 11 years after endovascular coiling. Before rehemorrhage occurred, serial magnetic resonance angiographies had revealed a stable situation with only a small base remnant after initial endovascular treatment. In the second clinical study, intraprocedural rupture during endovascular coiling occurred and a residual angiographic occult lesion was detected only during microsurgical clipping. In the third clinical study, we again found a residual lesion during microsurgical clipping. CONCLUSION: We present three clinical studies were the pathology at the base might has been underestimated in digital subtraction angiography or magnetic resonance angiography. The incidence of angiographic occult residuals is unknown, but their clinical relevance may be important. Beside other mechanisms, these lesions might be the source of aneurysmal regrowth and hemorrhage (Fig. 4, Ref. 27).

Central skull base osteomyelitis: new insights and implications for diagnosis and treatment.

Central skull base osteomyelitis (SBO) is a life-threatening disease originating from ear and from sinonasal infections. The intention of this study was to evaluate contemporary trends in etiology, diagnosis, management, and outcome of SBO and to draw the clinician's attention on this probably underestimated disease. Over a 6-year period we performed this systematic study in an academic quaternary medical care and skull base center including 20 patients (mean age 63.7 years) with central SBO, which is one of the largest series from a single center. In contrast to previous studies we explicitly excluded infections limited to malignant external otitis only but did not restrict central SBO to conditions unrelated to aural pathology. Fifteen patients had otogenic and five sinugenic SBO; four patients had fungal or mixed fungal infections. Pre-existing illnesses altering bone vascularization were detected in 70 % of the patients and had a negative effect on the improvement of cranial nerve palsies that were found in 14 patients. In relation, patients with otogenic SBO more often had local and systemic predisposing factors. Contrary to previous studies 16 patients (80 %) underwent surgical therapy and none of our patients died. A meta-analysis of five recent studies was done and compared with our own data and two previous meta-analyses. The present study highlights several important aspects with major implications for diagnosis and treatment of SBO that have not been adequately addressed as yet. In contrast to the restrictive attitude towards surgery in literature we recommend early and radical operative treatment to reduce its mortality.

Staged 'intentional' bridging vein ligation: a safe strategy in gaining wide access to skull base tumors.

BACKGROUND: The venous drainage of the temporal lobe, through bridging veins to the middle cranial fossa, is pivotal in determining the surgical corridor for skull base lesions. In dealing with select cases, where venous drainage was an obstacle in the surgical approach, we hypothesized that staged 'intentional' ligation of the dominant pathway of venous drainage would provide a safer and wider access to skull base tumors. We study the indications and safety of this surgical strategy in the management of skull base lesions. MATERIALS AND METHODS: From 1995 to 2012, 318 patients with skull base tumors were treated at our institute by the fronto-orbito-zygomatic (FOZ) or transpetrosal approaches, eight of whom we planned for staged 'intentional' bridging vein ligation. Seven patients underwent planned ligation of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage, followed by definitive surgery through the desired skull base approach, in the second stage, while in one patient the strategy was abandoned. These patients were evaluated with respect to their clinical presentation, pre- and post-operative radiology including venogram, intra-operative findings and post-operative course. RESULTS: Seven patients, four males and three females, with ages ranging from 16 to 63 years, underwent staged 'intentional' bridging vein ligation. The diagnoses were recurrent craniopharyngioma in four, and petroclival meningioma, sphenopetroclival meningioma and spheno-orbital meningioma in one each. Six of these lesions were approached from the dominant (left) side, while one lesion was on the right side. Venograms done after the first-stage procedure showed obliteration of the dominant venous drainage with opening up of anastomotic venous channels in all patients. All patients tolerated the first-stage procedure well; only one patient showed asymptomatic mild temporal lobe edema on MRI, which resolved in 3 weeks. None of the patients had venous complications after definitive surgery. One patient with recurrent chordoma, who was planned for staged ligation, did not undergo ligation as, intra-operatively, the draining channel turned out to be a cortical vein, which could be mobilized without ligation. CONCLUSION: In an attempt to detether the temporal lobe, the disconnection of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage may lead to re-direction of the venous outflow over time. This may allow skull base surgeons a better surgical corridor and ensure safety of venous structures during the definitive surgery.

Asymmetry of the anterior ethmoidal artery in relation to the anterior skull base: a population-based study of 500 arteries.

OBJECTIVE: To analyze variability in the distance between the Anterior Ethmoidal Artery (AEA) and the anterior Skull Base (SB), as well as the frequency of lateral asymmetry in a Latin American population using computed tomography. METHODS: A total of 250 computed tomography scans of paranasal sinuses in coronal reconstruction (500 AEAs) were analyzed. After determining the image with the best anatomical view of the artery, the distance between its midpoint and the ethmoidal roof was measured, and the images were independently interpreted by 2 physicians. RESULTS: Of the 500 AEAs, 279 (55.8%) adhered to or passed through the SB at a distance of 0mm. A total of 221 AEAs (44.2%) were at some distance from the SB, of which 107 (48.4%) were on the right side, ranging from 1.18 to 6.75mm, and 114 (51.5%) were on the left side, ranging from 1.15 to 6.04mm. The overall mean distance between the AEA and SB was 1.22 (SD=1.57) mm, increasing to 2.77 (SD=1.14) when the arteries adhered to the SB were excluded. Seventy-six individuals (30.4%) had a lateral distance variation > 1mm. CONCLUSION: Our study includes the largest sample of AEA analyzed with computed tomography scans of paranasal sinuses. There was some distance between the AEA and SB in almost half the patients, and we found a high rate of lateral variability >1mm. LEVEL OF EVIDENCE: Level 3.

Eyebrow craniotomy for anterior skull base lesions: how I do it.

BACKGROUND: The eyebrow craniotomy is a less invasive alternative approach for accessing anterior skull base lesions, compared to traditional and more extensive exposures. We give a stepwise description of this minimally invasive technique with discussion on the indications, limitations and key aspects of perioperative management. METHODS: Positioning of the head and planning the surgical corridor are dictated by the nature, site and size of the target lesion. The eyebrow incision should spare the medial and posterolateral neural structures. Microsurgical strategy is based on opening up the basal cisterns and respecting the distorted neurovascular anatomy. Selective use of brain retractor and angulation of the operative microscope enable the surgeon to make use of the "keyhole effect" for accessing a larger target. Perioperative measures are in part dictated by the nature of the pathology, involvement of the optic apparatus and changes to pituitary function. CONCLUSION: The eyebrow craniotomy may be safely used as a minimally invasive approach for a variety of anterior skull base lesions. There is an operative learning curve and some types of pathologies are easier to approach by this technique than others. KEY POINTS: • The eyebrow craniotomy is an alternative less invasive approach for accessing anterior skull base lesions • Positioning of the head and planning the surgical corridor are dictated by the nature, site and size of the target lesion • Microsurgical strategy is based on opening up the basal cisterns and respecting the distorted neurovascular anatomy. • Selective use of brain retractor and angulation of the operative microscope enable the surgeon to make use of the "keyhole effect" for accessing a larger target • Perioperative measures are in part dictated by the nature of the pathology, involvement of the optic apparatus and changes to pituitary function. • There is an operative learning curve and some types of pathologies are easier to approach by this technique than others.

Tissue dissection before direct manipulation to the pathology with pulsed laser-induced liquid jet system in skull base surgery--preservation of fine vessels and maintained optic nerve function.

BACKGROUND: Most difficulties in skull base tumor removal are generally caused by adhesion of feeding arteries to the vital structures and cranial nerves. Water jet technology provides tissue dissectability with preservation of fine blood vessels both in experimental and clinical situations. However problems still remain regarding whether tumor removal with preservation of peripheral nerve function is possible or not. This clinical investigation evaluated functional preservation of peripheral nerves and dissectability with a newly developed pulsed laser-induced liquid jet (LILJ) system under intraoperative electrophysiological monitoring. METHODS: The LILJ system was used to treat 21 patients with skull base tumors manifesting as severe visual disturbance through the extended transsphenoidal approach. The LILJ system consists of a bayonet-shaped catheter incorporating a jet generator, and total weight is around 7 g. Intraoperative visual evoked potential (VEP), and pre/postoperative conventional visual assessments were investigated. RESULTS: Precise dissections of the tumor were obtained, resulting in gross total removal in 19 of 21 patients. Two patients with meningiomas with tight adhesion to the origin of the lenticulostriate arteries had small remnants. Of the 21 patients, 16 showed immediate improvement on intraoperative VEP, 2 had no change, and 3 had prolonged latency, which required intermittent suspension of procedure. A total of 20 patients and 40 eyes showed good recovery at discharge, and all patients evaluated had recovered good visual status. CONCLUSIONS: The LILJ system can achieve safe and optimal removal with functional preservation of optic nerves, probably because of the high resistance of the arachnoidal sheath and fine vascular tissue.

Microsurgical anatomy of the infratemporal fossa.

The objective of this study is to clearly and precisely describe the topography and contents of the infratemporal fossa. Ten formalin-fixed, adult cadaveric specimens were studied. Twenty infratemporal fossa were dissected and examined using micro-operative techniques with magnifications of 3-40×. Information was obtained about the inter-relationships of the contents of the infratemporal fossa. The infratemporal fossa lies at the boundary of the head and neck, and the intracranial cavity. It is surrounded by the maxillary sinus anteriorly, the mandible laterally, the pterygoid process anteromedially, and the parapharyngeal space posteromedially. It contains the maxillary artery and its branches, the pterygoid muscles, the mandibular nerve, and the pterygoid venous plexus. The course and the anatomic variation of the maxillary artery and the branches of the mandibular nerve were demonstrated. The three-dimensional (3D) relationships between the important bony landmarks and the neurovascular bundles of the infratemporal fossa were also shown. The skull base anatomy of the infratemporal fossa is complex, requiring neurosurgeons and head and neck surgeons to have a precise knowledge of 3D details of the topography and contents of the region. A detailed 3D anatomic knowledge is mandatory to manage benign or malignant lesions involving the infratemporal fossa without significant postoperative complications.

The petrosal artery and its variations: a comprehensive review and anatomical study with application to skull base surgery and neurointerventional procedures.

BACKGROUND: The petrosal artery supplies several structures at the skull base and is often the focus of various neurointerventional procedures. Therefore, knowledge of its anatomy and variations is important to surgeons and interventionalists. MATERIALS AND METHODS: Twenty latex injected cadaveric heads (40 sides) underwent microsurgical dissection of the petrosal artery. Documentation of the course of the artery and its branches were made. Measurements of the petrosal artery's length and diameter were performed using microcallipers. RESULTS: A petrosal artery was identified on all sides. The mean length and diameter of the artery within the middle cranial fossa was 2.4 cm and 0.38 mm, respectively. Branches included the following: dural, ganglionic, V3 branches, branches extending through the foramen ovale, branches directly to the greater petrosal and lesser petrosal nerves, branches to the floor of the hiatus of the greater and lesser petrosal nerves, branch to the arcuate eminence, and superior tympanic artery. No statistically significant differences were noted between male and female specimens, but right-sided petrosal arteries were in general, larger in diameter than left sides. CONCLUSIONS: A thorough anatomical knowledge of the petrosal artery and to its relationship to the facial nerve and other neurovascular structures is necessary to facilitate effective endovascular treatment and to preclude facial nerve complications.

Initial experiences with the Amplatzer Vascular Plug 4 for permanent occlusion of the internal carotid artery in the skull base in patients with head and neck tumors.

INTRODUCTION: As the first report in the literature, we present our initial experiences with the latest generation's Amplatzer Vascular Plug 4 (AVP4) as a device for permanent occlusion of the internal carotid artery in its course in the skull base. METHODS: Permanent occlusion of the internal carotid artery in the skull base was performed in four patients after administration of an intravenous heparin bolus (three patients preoperatively to facilitate radical surgery of head and neck tumors, one patient with a palliative intent to reduce tumor arrosion bleeding risk). RESULTS: In all patients, the deployment of the AVP4 in the artery's course in the skull base was feasible. In two patients, placement was possible in the cavernous segment of the internal carotid artery, and in the other two patients, more proximal in the artery's foramen lacerum and petrous segment, respectively. Occlusion was accomplished in one patient with one AVP4 (occlusion time 25 min), in two patients with two AVP4 (occlusion time 20 min in each case), and in one patient with one AVP4, three additional fibered coils and two Gelfoam pledgets (occlusion time more than 2 h). Complications did not occur in any of the four patients. CONCLUSION: The AVP4 may be a promising device for permanent occlusion of the internal carotid artery, allowing in its latest generation, navigability as distal as the cavernous segment in some, but not in all cases. Difficulties may still occur in very tortuous vessel anatomy.

Microsurgical anatomy of distal medial striate artery (recurrent artery of Heubner).

INTRODUCTION: In literature, many controversies exist about courses and terminology of the distal medial striate artery (DMSA) or recurrent artery first described by Heubner near 1872. The purpose of this study was to define the accurate anatomy of this artery, to help the practitioners during surgery of the anterior cerebral-anterior communicating arteries (ACA-ACoA) complex. MATERIALS AND METHODS: 20 cranial bases were examined using magnification of the surgical microscope. One half for which the internal carotid arteries and internal jugular veins were dissected, cannulated and perfused with colored silicon on fresh cadavers; the other half only with arterial injection of formalin-fixed normal adult human brains. RESULTS: The artery arose principally from A2 segment (58%), always less than 5 mm up to downstream from ACA to ACoA junction. In 59.5% it had a recurrent course anterior to A1 segment. It terminated in one to three stems which entered the medial part of the anterior perforated substance. The DMSA was present as a single vessel in 95% of cases. Its main outer diameter was 0.7 mm and the length had an average of 24 mm. CONCLUSION: Iatrogenic damage or occlusion leads to a mediobasal striatum infarction with important neurological deficits such as brachiofacial hemiparesis and aphasia. This artery should be routinely identified during clipping of ACoA aneurysm. Special attention in this study was given to atypical posterior course or anatomic variations such as double DMSA on a same side.

The medial tentorial artery of Bernasconi-Cassinari: a comprehensive review of its anatomy and neurosurgical importance.

PURPOSE: The medial tentorial artery (MTA) of Bernasconi-Cassinari has been associated with many neurosurgical pathologies, including tentorial and petroclival meningiomas, dural arteriovenous fistulae, hemangioblastomas, moyamoya disease, arteriovenous malformations, trigeminal neuromas, and malignant gliomas. This vessel may function as a source of collateral blood supply for the posterior circulation. Our goal was to elucidate the MTA by compiling information about it in one concise article for clinicians and neurosurgeons who need to know about the anatomy and clinical significance of this artery. METHODS: We reviewed the medical literature for information dealing with the anatomy, pathology, and surgery of the MTA and its clinical implications. RESULTS: Based on the literature, the MTA commonly arises from the cavernous segment of the internal carotid artery and at times, may provide important collateral blood flow to the posterior circulation. This vessel is roughly 2 cm long and has a wavy appearance on angiography. It is usually a single trunk and often supplies the oculomotor, trochlear, and abducens nerves. The MTA may be seen on normal angiography and may be involved in the blood supply of petroclival and tentorial meningiomas. CONCLUSIONS: A thorough knowledge of its anatomy and variations is important to clinicians interpreting imaging and neurosurgeons operating in this region. Detailed knowledge of this vessel may shed light on therapeutic options regarding its associated pathologies.

Pulsed laser-induced liquid jet for skull base tumor removal with vascular preservation through the transsphenoidal approach: a clinical investigation.

BACKGROUND: The transsphenoidal approach has recently been used to treat complex lesions beyond the sella turcica, but the difficulties of dealing with small vessels, deep and narrow space, and working angle may limit the procedures. To overcome these problems, we have developed a pulsed laser-induced liquid jet (LILJ) system to dissect tumor tissue with preservation of fine blood vessels within deep and narrow working spaces and evaluated its utility and safety. METHODS: The LILJ system was applied to 14 consecutive patients with uncharacteristically complex skull base tumor treated through the extended transsphenoidal approach. This system consists of a bayonet-shaped catheter incorporating a jet generator formed of stainless tube (external diameter 1.10 mm, internal diameter 0.78 mm), which was surrounded by a coaxial polytetrafluoroethylene 14-G equivalent suction tube to be able to incorporate into the confined working spaces. Minor modifications could be fitted for the catheter (15 to 18 cm length, straight or side flexion tip), and total weight was around 7 g. FINDINGS: Precise dissection and mass reduction of the tumor were obtained in all cases except one recurrent case of chordoma with significant fibrosis due to radiation. Both small arteries and veins were preserved, allowing subsequent microsurgical devascularization. Intraoperative blood loss was minimal, and tumor removal rate was satisfactory after the introduction of the system. No complication was related to use of the LILJ system. CONCLUSION: Although comparison between conventional surgical instruments is mandatory in the future, the present study suggests that the LILJ system can achieve safe and optimum removal of complex skull base tumor. Potential application for minimally invasive endoscopic system, as well as potentials for changing the design of the catheter in according to preference of surgeon with low cost, may give advantages over conventional surgical instruments.