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Object Image-guided frameless stereotactic techniques provide an alternative to traditional head-frame fixation in the performance of fine-needle biopsies. However, these techniques still require rigid head fixation, usually in the form of a head holder. The authors report on a series of fine-needle biopsies and brain abscess aspirations in which a frameless technique was used with a patient's head supported on a horseshoe headholder. To validate this technique, they performed an in vitro accuracy study. Methods Forty-eight patients underwent fine-needle biopsy of intracranial lesions that ranged in size from 0.9 to more than 107.7 ml; a fiducial-less, frameless, image-guided technique was used without rigid head fixation. In 1 of the 48 patients a cerebral abscess was drained. The accuracy study was performed with a skull phantom that was imaged with a CT scanner and tracked with a registration mask containing light-emitting diodes. The objective was a skin fiducial marker with a 4-mm circular target to accommodate the 2.5-mm biopsy needle. A series of 50 trials was conducted. Results Diagnostic tissue was obtained on the first attempt in 47 of 48 brain biopsy cases. In 2 cases small hemorrhages at the biopsy site were noted as a complication on the postoperative CT scan. One of these hemorrhages resulted in hand and arm weakness. The accuracy study demonstrated a 98% success rate of the biopsy needle passing through the 4-mm circular target using the registration mask as the registration and tracking device. This demonstrates a ± 0.75-mm tolerance on the targeting method. Conclusions The accuracy study demonstrated the ability of the mask to actively track the target and allow navigation to a 4-mm-diameter circular target with a 98% success rate. The frameless, pinless, fiducial-less technique described herein will likely be another safe, fast alternative to frame-based stereotactic techniques for fine-needle biopsy that avoids the potential morbidity of rigid head-pin fixation. Furthermore, it should lend itself to other image-guided applications such as the placement of ventricular catheters for shunting or Ommaya reservoirs.

The authors report the safety and efficacy of using a percutaneous minimal-access insertion technique for distal shunt catheter placement in 100 cases. From June 2007 to March 2008, they attempted 100 minimal-access insertions of distal shunt catheters in 91 patients who required ventriculoperitoneal shunting. Using the minimal-access approach, they avoided utilizing laparoscopic assistance or a mini-laparotomy in 91% of the cases. There were no bowel injuries or misplaced distal catheters. Additional outcomes in terms of operative times, cases that required conversion to open or laparoscopically assisted implantation, and infection rates are presented. They conclude that intraperitoneal shunt catheter placement can be safely and effectively accomplished using a simplified percutaneous minimal-access insertion method that does not require direct laparoscopic visualization.

Object The authors introduce a novel technique of intraparenchymal brain tumor resection using a rod lens endoscope and parallel instrumentation via a transparent conduit. Methods Over a 4-year period, 21 patients underwent completely endoscopic removal of a subcortical brain lesion by means of a transparent conduit. Image guidance was used to direct the cannulation and resection of all lesions. Postoperative MR imaging or CT was performed to assess for residual tumor in all patients, and all patients were followed up postoperatively to assess for new neurological deficits or other surgical complications. Results The histopathological findings were as follows: 12 metastases, 5 glioblastomas, 3 cavernous malformations, and 1 hemangioblastoma. Total radiographically confirmed resection was achieved in 8 cases, near-total in 6 cases, and subtotal in 7 cases. There were no perioperative deaths. Complications included 1 infection and 1 pulmonary embolus. There were no postoperative hematomas, no postoperative seizures, and no worsened neurological deficits in the immediate postoperative period. Conclusions Fully endoscopic resection may be a technically feasible method of resection for selected subcortical masses. Further experience with this technique will help to determine its applicability and safety.

✓Craniopharyngiomas have always been an extremely challenging type of tumor to treat. The transsphenoidal route has been used for resection of these lesions since its introduction. The authors present a historical review of the literature from the introduction of the endonasal route for resection of craniopharyngiomas until the present. Abandoned early due to technological limitations, this approach has been expanded both in its application and in its anatomical boundaries with subsequent progressive improvements in outcomes. This expansion has coincided with advances in visualization devices, imaging guidance techniques, and anatomical understanding. The progression from the use of headlights, to microscopy, to endoscopy and fluoroscopy, and finally to modern intraoperative magnetic resonance–guided techniques, combined with collaboration between otolaryngologists and neurosurgeons, has provided the framework for the development of current techniques for the resection of sellar and suprasellar craniopharyngiomas.

Object Craniopharyngiomas are notoriously difficult to treat. Surgeons must weigh the risks of aggressive resection against the long-term challenges of recurrence. Because of their parasellar location, often extending well beyond the sella, these tumors challenge vision and pituitary and hypothalamic function. New techniques are needed to improve outcomes in patients with these tumors while decreasing treatment morbidity. An endoscopic expanded endonasal approach (EEA) is one such technique that warrants understanding and evaluation. The authors explain the techniques and approach used for the endoscopic endonasal resection of suprasellar craniopharyngiomas and introduce a tumor classification scheme. Methods The techniques and approach used for the endoscopic, endonasal resection of suprasellar craniopharyngiomas is explained, including the introduction of a tumor classification scheme. This scheme is helpful for understanding both the appropriate expanded approach as well as relevant involved anatomy. Results The classification scheme divides tumors according to their suprasellar extension: Type I is preinfundibular; Type II is transinfundibular (extending into the stalk); Type III is retroinfundibular, extending behind the gland and stalk, and has 2 subdivisions (IIIa, extending into the third ventricle; and IIIb, extending into the interpeduncular cistern); and Type IV is isolated to the third ventricle and/or optic recess and is not accessible via an endonasal approach. Conclusions The endoscopic EEA requires a thorough understanding of both sinus and skull base anatomy. Moreover, in its application for craniopharyngiomas, an understanding of tumor growth and extension with respect to the optic chiasm and infundibulum is critical to safely approach the lesion via an endonasal route.

✓ Cerebrospinal fluid (CSF) leakage following endoscopic endonasal skull base resection can be a significant problem. A method for securing tissue grafts is needed. In this paper the authors used an endonasal suturing device to secure the graft reconstruction following endonasal tumor resection. The U-Clip anastomotic device (Medtronic), developed for cardiovascular anastomoses, was used to secure the tissue graft to native dura. A specialized needle driver and hemoclip applier were used for the application and deployment of this device. No suture tying was necessary, facilitating its endonasal application. The graft was successfully secured in its desired position to native dura by using the U-Clip anastomotic device. The patient did not suffer a postoperative CSF leak, and postoperative imaging and endoscopy revealed that the graft was in a good position. There was no complication from the use of the device. The U-Clip anastomotic device can be used as a suture device during endonasal surgery. It may prevent tissue graft migration and help prevent CSF leakage.

✓ The purpose of this study was to describe the technique used to safely identify the petrous carotid artery during expanded endonasal approaches to the skull base. A series of 20 cadaveric studies was undertaken to isolate the vidian artery and nerve and to use them as landmarks to the petrous internal carotid artery (ICA). Twenty-five consecutive paraclival endoscopic cases were also reviewed to determine the consistency of the vidian artery in vivo as an intraoperative landmark to the ICA. These data were then correlated with results from a separate study in which computed tomography scans from 44 patients were evaluated to delineate the course of the vidian canal and its relationship to the petrous ICA. In all 20 cadaveric dissections and all 25 surgical cases, the vidian artery was consistently identified and could be reliably used as a landmark to the ICA. The correlation between anatomical and clinical data in this paper supports the consistent use of the vidian artery as an important landmark to the petrous ICA.

✓Paraclinoidal aneurysms, especially superior hypophyseal artery (SHA) aneurysms (with medial projection), can be challenging to access via a pterional craniotomy and damage to the optic nerve can occur during surgery. The authors have previously reported on endonasal clipping and aneurysmorrhaphy of a vertebral artery aneurysm following proximal and distal protection of the aneurysm using partial coil embolization. To the best of the authors' knowledge no unprotected aneurysm has been clipped using an endonasal approach. The 56-year-old woman in this report was found to have two unruptured aneurysms: an anterior communicating artery (ACoA) aneurysm and an SHA aneurysm. An endoscopic endonasal, transplanar–transsellar approach was used to successfully clip the SHA aneurysm. Proximal and distal control was obtained endonasally prior to successful clip occlusion of the aneurysm. The ACoA aneurysm was clipped via a pterional craniotomy during the same anesthetic session. This report shows that it is possible to successfully clip a medially projecting, paraclinoidal aneurysm using an endonasal approach. Such cases must be chosen with extreme caution and only performed by surgeons with significant experience with both endoscopic endonasal approaches and neurovascular surgery.

Object Transsphenoidal approaches have been used for a century for the resection of pituitary and other sellar tumors. Recently, however, the standard endonasal approach has been expanded to provide access to other parasellar lesions. With the addition of the endoscope, this expansion has significant potential for the resection of skull base lesions. Methods The anatomical landmarks and surgical techniques used in expanded (extended) endoscopic approaches to the clivus and cervicomedullary junction are reviewed and presented, accompanied by case illustrations of each segment (or module) of approach. The caudal portion of the midline anterior skull base and the cervicomedullary junction is divided into modules of approach: the middle third of the clivus, its lower third, and the cervicomedullary junction. Case illustrations of successful resections of lesions via each module of the approach are presented and discussed. Conclusions Endoscopic expanded endonasal approaches to caudally located midline anterior skull base and cervicomedullary lesions are feasible and hold great potential for decreased morbidity. The effectiveness and appropriate use of these techniques must be evaluated by close examination of outcomes as case series expand.

Object Transsphenoidal approaches have been used for a century for the resection of pituitary and other sellar tumors. More recently, the standard endonasal approach has been expanded to provide access to other, parasellar lesions. With the addition of the endoscope, this expansion carries significant potential for the resection of skull base lesions. Methods The anatomical landmarks and surgical techniques used in expanded (extended) endoscopic approaches to the rostral, anterior skull base are reviewed and presented, accompanied by case illustrations of each segment (or module) of approach. The rostral half of the anterior skull base is divided into modules of approach: sellar/parasellar, transplanum/transtuberculum, and transcribriform. Case illustrations of successful resections of lesions with each module are presented and discussed. Conclusions Endoscopic, expanded endonasal approaches to rostral anterior skull base lesions are feasible and hold great potential for decreased morbidity. The effectiveness and appropriate use of these techniques must be evaluated by close examination of outcomes as case series expand.

Harvey Cushing first popularized the transsphenoidal route to the sella turcica, and Jules Hardy subsequently refined it by adding the operating microscope. Over the ensuing decades, attempts at extending the application of this approach have been advanced by Edward Laws and others. With the evolution of endoscopic approaches, the natural expansion of their use to intradural lesions followed. For the expanded endonasal approach to become a viable option, the paramount concerns surrounding consistent reconstruction of the dura mater must be overcome. In this review the authors chronicle the evolution of the reconstruction technique they currently use after performing expanded endonasal approaches. They also report the use of a balloon stent to buttress the reconstruction and counter the effects of graft migration and cerebrospinal fluid fistula formation. The technique described in this report represents an important step forward in the reconstruction of defects resulting from expanded endonasal approaches.

Object The middle third of the clivus and the region around the petrous internal carotid artery (ICA) is a difficult area of the skull base in terms of access. This is a deep area rich with critical neurovascular structures, which is often host to typical skull base diseases. Expanded endoscopic endonasal approaches offer a potential option for accessing this difficult region. The objective of this paper was to establish the clinical feasibility of gaining access to the paraclival space in the region of the middle third of the clivus, to provide a practical modular and clinically applicable classification, and to describe the relevant critical surgical anatomy for each module. Methods The anatomical organization of the region around the petrous ICA, cavernous sinus, and middle clivus is presented, with approaches divided into zones. In an accompanying paper in this issue by Cavallo, et al., the anatomy of the pterygopalatine fossa is presented; this was observed through cadaveric dissection for which an expanded endonasal approach was used. In the current paper the authors translate the aforementioned anatomical study to provide a clinically applicable categorization of the endonasal approach to the region around the petrous ICA. A series of zones inferior and superior to the petrous ICA are described, with an illustrative case presented for each region. Conclusions The expanded endonasal approach is a feasible approach to the middle third of the clivus, petrous ICA, cavernous sinus, and medial infratemporal fossa in cases in which the lesion is located centrally, with neurovascular structures displaced laterally.

The increasing popularity of minimally invasive neurosurgery has led to the development of transnasal expanded approaches for the treatment of skull base lesions. One of the greatest challenges in safely accomplishing resection of tumors, particularly intradural lesions, is effective hemostasis. Over the past 7 years the authors have progressively developed an organized approach to address this challenge. This has required the development of new instrumentation as well as variations on standard techniques. In this report they present the technique that has evolved at their institution for endoneurosurgical hemostasis.