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Introduction Spinal cord tumors (SCT) are relatively uncommon and usually require surgical treatment. Readmission within 30 days after discharge is an important indicator of health care quality. The aim of this study was to investigate the rates and causes of unplanned readmissions and reoperations after SCT surgery. Methods A retrospective analysis of patients’ charts at a single center from May 2007 to September 2015 was completed. Inclusion criteria: history of laminectomy with excision of neoplasm in the spinal cord. Exclusion criteria: (1) surgery outside the timeframe; (2) less than 19 years old; (3) non-neoplastic intramural pathologies; (4) previous resection at the same location; (5) metastatic lesions. Results We found 131 patients that met criteria. Six patients (4.5%) were readmitted within 30 days and two within 90 days (1.5%). Four underwent reoperation: one for a cerebrospinal fluid leak, two for pseudomenigoceles, and one for repeat laminectomy. Resection of intramedullary tumors resulted in twice the risk of having one or more complications compared to extramedullary tumors (RR 2.0; 95% CI: 1.0–4.2; p = 0.057), and nearly four times the risk of having a neurological complication (RR 3.8; 95% CI 1.5–9.5; p = 0.005). Conclusion This study analyzes readmission, reoperation and complication rates for the surgical care of SCT highlighting how SCT surgery is still involved with morbidity in experienced and specialized centers. This information is useful both for health care enhancement projects and for evidence-based patient counseling.

Introduction The binocular operating microscope has been the visualization instrument of choice for microsurgical clipping of intracranial aneurysms for many decades. Objective To discuss recent technological advances that have provided novel visualization tools, which may prove to be superior to the binocular operating microscope in many regards. Methods We present an operative video and our operative experience with the BrightMatterTM Servo System (Synaptive Medical, Toronto, Ontario, Canada) during the microsurgical clipping of an anterior communicating artery aneurysm. To the best of our knowledge, the use of this device for the microsurgical clipping of an intracranial aneurysm has never been described in the literature. Results The BrightMatterTM Servo System (Synaptive Medical) is a surgical exoscope which avoids many of the ergonomic constraints of the binocular operating microscope, but is associated with a steep learning curve. The BrightMatterTM Servo System (Synaptive Medical) is a maneuverable surgical exoscope that is positioned with a directional aiming device and a surgeon-controlled foot pedal. While utilizing this device comes with a steep learning curve typical of any new technology, the BrightMatterTM Servo System (Synaptive Medical) has several advantages over the conventional surgical microscope, which include a relatively unobstructed surgical field, provision of high-definition images, and visualization of difficult angles/trajectories. Conclusion This device can easily be utilized as a visualization tool for a variety of cranial and spinal procedures in lieu of the binocular operating microscope. We anticipate that this technology will soon become an integral part of the neurosurgeon's armamentarium.

IgG4-related hypophysitis is a rare clinical entity that forms part of an emerging group of multi-organ IgG4-related fibrosclerotic systemic diseases. The rare prevalence of the disease, presenting features that overlap with other sellar pathologies, and variable imaging features can make preoperative identification challenging. We report three cases of isolated IgG4-related hypophysitis with atypical clinical and imaging features that mimicked those of pituitary apoplexy and other sellar lesions. Additionally, we review the literature of IgG4-related hypophysitis to provide context for individual patient data described herein. All patients presented with symptoms that mimicked those of pituitary apoplexy and visual disturbance, and MRI findings suggestive of pituitary macroadenoma, Rathke’s cleft cyst and craniopharyngioma. The clinical presentation warranted surgical decompression, resulting in rapid symptomatic improvement. Preoperative high-dose followed by postoperative low-dose glucocorticoid replacement therapy was administered in all cases. Histopathology showed dense infiltrate of IgG4 cells. Post-operative follow-up monitoring for 12–26 months revealed normal serum IgG4 levels with no other organ involvement, while endocrinological testing revealed persistent pituitary hormone deficiencies. Our cases highlight the importance of considering IgG4-related hypophysitis in the differential diagnosis of solid and cystic sellar lesions presenting acutely with pituitary apoplexy symptoms. Existing diagnostic criteria may not be sufficiently precise to permit rapid and reliable identification, or avoidance of surgery in the acute setting. In contrast to other reports of the natural history of this condition, despite the severity of presenting features, the disease in our cases was pituitary-restricted with normal serum IgG4 levels.

OBJECT Middle fossa floor dehiscence (MFFD) can present as multiple syndromes depending on dehiscence location, tissue herniation, and dural integrity. The authors propose a classification system for MFFD with the potential to guide clinical decision making. METHODS A retrospective analysis of the electronic medical records (years 1995–2012) of patients who had undergone temporal craniotomy for the surgical repair of an MFFD syndrome at a single institution was undertaken. Reviewed data included demographic, operative, presentation, and outcome details. Middle fossa floor dehiscence was classified as follows: Class A, bony dehiscence without herniation of the brain and/or meninges; Class B, herniation of the brain and/or meninges through the middle fossa floor without CSF leakage; Class C, dehiscence with CSF leakage without meningitis; or Class D, dehiscence with meningitis. RESULTS Fifty-one patients, 22 males and 29 females, were included in the analysis. The mean age was 48.7 ± 15.5 years, mean body mass index was 32.65 ± 6.86 kg/m2, and mean symptom duration was 33 ± 42 months. Seven patients underwent repeat surgery for symptomatic recurrence; therefore, there were 58 surgical encounters. Repair included bony reconstruction with hydroxyapatite with or without resection of encephaloceles and/or repair of a dural defect. According to the MFFD classification system described, 15, 8, 27, and 8 cases were categorized as Class A, B, C, and D, respectively. The prevalence of hearing loss was 87%, 63%, and 70% in Classes A, B, and C, respectively. Vestibular symptoms were more prevalent in Class A. Seven patients reported persistent symptoms at the last follow-up. Transient complications were similar in each classification (13%–25%), and a single permanent complication related to anesthesia was observed. There were no mortalities or severe neurological morbidities in the series. CONCLUSIONS Middle fossa floor dehiscence has a spectrum of clinical presentations. A classification system may help to clarify the diagnosis and guide therapy. Surgery, the mainstay of treatment, is safe and well tolerated.

Objective To analyze whether cavernous sinus sampling (CSS) and dynamic magnetic resonance imaging (dMRI) are consistent with intraoperative findings in Cushing disease (CD) patients. Design Retrospective outcomes study. Setting Oregon Health & Science University; 2006 and 2013. Participants A total of 37 CD patients with preoperative dMRI and CSS to confirm central adrenocorticotropic hormone (ACTH) hypersecretion. Patients were 78% female; mean age was 41 years (at diagnosis), and all had a minimum of 6 months of follow-up. Main Outcome Measures Correlations among patient characteristics, dMRI measurements, CSS results, and intraoperative findings. Results All CSS indicated presence of CD. Eight of 37 patients had no identifiable tumor on dMRI. Three of 37 patients had no tumor at surgery. dMRI tumor size was inversely correlated with age (rs = − 0.4; p = 0.01) and directly correlated to intraoperative lateralization (rs = 0.3; p

The retrosigmoid craniotomy is a modification of the traditional suboccipital craniotomy, which was first described in the literature by Frankel et al. in 1904 [1, 2]. The suboccipital craniotomy provides a wide view of the posterior cranial fossa from the tentorium cerebelli to the foramen magnum. Although new technologies and techniques have been introduced to make the approach safer, it is a testament to its versatility that this surgical approach continues to be used nearly unchanged from its original description over a century ago [1].

Background Anterior and posterior clinoidectomies have been proposed to augment exposure of the basilar apex. A sequential quantitative benefit analysis offered by these maneuvers has not been reported. Methods Fourteen datasets from eight cadaveric specimens were analyzed. A modified orbitozygomatic frontotemporal craniotomy was performed. The extent of proximal control of the basilar artery was determined through the exposed opticocarotid and carotidoculomotor triangles before and after clinoidectomies and mobilization of the third nerve at the porous oculomotarius. Results Removal of the anterior and posterior clinoids significantly improved proximal basilar artery access (p Conclusion Anterior and posterior clinoidectomies significantly improved the area of exposure of the opticocarotid triangle, carotidoculomotor triangle, and the exposed length of the basilar artery available for proximal control. This improvement is extremely important for large or giant aneurysms of the upper basilar artery or aneurysms hidden by the posterior clinoid.

Appropriate management of adult gliomas requires an accurate histopathological diagnosis. However, the heterogeneity of gliomas can lead to misdiagnosis and undergrading, especially with biopsy. We evaluated the role of preoperative relative cerebral blood volume (rCBV) analysis in conjunction with histopathological analysis as a predictor of overall survival and risk of undergrading. We retrospectively identified 146 patients with newly diagnosed gliomas (WHO grade II–IV) that had undergone preoperative MRI with rCBV analysis. We compared overall survival by histopathologically determined WHO tumor grade and by rCBV using Kaplan–Meier survival curves and the Cox proportional hazards model. We also compared preoperative imaging findings and initial histopathological diagnosis in 13 patients who underwent biopsy followed by subsequent resection. Survival curves by WHO grade and rCBV tier similarly separated patients into low, intermediate, and high-risk groups with shorter survival corresponding to higher grade or rCBV tier. The hazard ratio for WHO grade III versus II was 3.91 (p = 0.018) and for grade IV versus II was 11.26 (p

Objectives To analyze surgical outcomes and predictive factors of disease remission in acromegaly patients who underwent microscopic transsphenoidal surgery (TSS) for a growth hormone (GH)-secreting adenoma. Design A 6-year retrospective review of 86 consecutive acromegaly surgeries. Setting Procedures performed at a single institution by a single surgeon. Participants Seventy acromegaly patients. Main Outcome Measures Demographic information, preoperative laboratory values, tumor imaging data, and morphological and immunohistochemical data were collected. Predictive values using the latest and most stringent biochemical remission criteria were determined using univariate and multivariate statistical analyses. Results Remission rate for 59 (18 males) acromegaly patients meeting the study inclusion criteria was 52.5%. Remission rates for micro- and macroadenomas were 81.8% and 45.8%, respectively. Patients of older age, with a smaller tumor, lower Knosp grade, lower preoperative GH, and insulinlike growth factor 1 levels were more likely to achieve remission. Remission rate decreased significantly with repeat surgeries. Those patients with adenomas that stained positive for somatostatin receptor subtype 2A were less likely to experience tumor recurrence and more likely to respond to medical treatment with persistent or elevated GH hypersecretion. Conclusions Microscopic TSS continues to be a viable means for treating acromegaly patients. Patients should be followed long term.

Object This study was designed to determine if the “keyhole concept,” proposed by Perneczky's group, can be verified quantitatively. Methods Fourteen (3 bilateral and 8 unilateral) sides of embalmed latex-injected cadaveric heads were dissected via 3 sequential craniotomy approaches: supraorbital keyhole, frontotemporal pterional, and supraorbital. Three-dimensional cartesian coordinates were recorded using a stereotactic localizer. The orthocenter of the ipsilateral anterior clinoid process, the posterior clinoid process, and the contralateral anterior clinoid process are expressed as a center point (the apex). Seven vectors project from the apex to their corresponding target points in a radiating manner on the parasellar skull base. Each 2 neighboring vectors border what could be considered a triangle, and the total area of the 7 triangles sharing the same apex was geometrically expressed as the area of exposure in the parasellar region. Results Values are expressed as the mean ± SD (mm2). The total area of exposure was as follows: supraorbital keyhole 1733.1 ± 336.0, pterional 1699.3 ± 361.9, and supraorbital 1691.4 ± 342.4. The area of exposure on the contralateral side was as follows: supraorbital keyhole 602.2 ± 194.7, pterional 595.2 ± 228.0, and supraorbital 553.3 ± 227.2. The supraorbital keyhole skull flap was 2.0 cm2, and the skull flap size ratio was 1:5:6.5 (supraorbital keyhole/pterional/supraorbital). Conclusions The area of exposure of the parasellar region through the smaller supraorbital keyhole approach is as adequate as the larger pterional and supraorbital approaches. The keyhole concept can be verified quantitatively as follows: 1) a wide area of exposure on the skull base can be obtained through a small keyhole skull opening, and 2) the side opposite the opening can also be visualized.

Object The optimal timing of cranioplasty after decompressive craniectomy for stroke is not known. Case series suggest that early cranioplasty is associated with higher rates of infection while delaying cranioplasty may be associated with higher rates of bone resorption. The authors examined whether the timing of cranioplasty after decompressive craniectomy for stroke affects postoperative complication rates. Methods A retrospective cohort study was undertaken to evaluate complication rates in patients undergoing cranioplasty at early (within 10 weeks of craniectomy) or late (≥ 10 weeks) stages. Multivariate logistic regression analysis was used to determine characteristics that would predict complications in patients undergoing cranioplasty after decompressive craniectomy for stroke. Results While the overall complication rate was higher in the early cranioplasty cohort (22% vs 16% in the late cranioplasty cohort), the difference was not statistically significant (p = 0.5541). Patients in the early cranioplasty cohort had lower rates of postoperative hematoma but higher rates of infection. Presence of a CSF shunt was the only significant predictor of complications (OR 8.96, 95% CI 1.84–43.6). Conclusions Complications rates for early cranioplasty (within 10 weeks of craniectomy) are similar to those encountered when cranioplasty is delayed, although the cohort size in this study was too small to state equivalence. Patients with a ventriculoperitoneal shunt are at higher risk for complications after cranioplasty.

Postoperative serum cortisol is used as an indicator of Cushing's disease (CD) remission following transsphenoidal surgery (TSS) and guides (controversially) the need for immediate adjuvant treatment for CD. We investigated postoperative cortisol and adrenocorticotropic hormone (ACTH) levels as predictors of remission/recurrence in CD in a large retrospective cohort of patients with pathologically confirmed CD, over 6 years at a single institution. Midnight and morning cortisol, and ACTH at 24-48 h postoperatively (24 h after last hydrocortisone dose) were measured. Remission was defined as normal 24-h urine free cortisol, normal midnight salivary cortisol, a normal dexamethasone-corticotropin releasing hormone (CRH) test or continued need for hydrocortisone, assessed periodically. Statistical analysis was performed using PASW 18. Follow up data was available for 52 patients (38 females and 14 males), median follow up was 16.5 month (range 2-143 months), median age was 45 years (range 21-72 years), 28 tumors were microadenomas and 16 were macroadenomas, and in eight cases no tumor was observed on magnetic resonance imaging. No patient with postoperative cortisol levels10 mcg/dl were found to be in remission. Ten of the 52 patients with cortisol10 mcg/dl by postoperative day 1-2 underwent a second TSS within 7 days. Forty-three patients (82.7%) achieved CD remission (36 after one TSS and 7 after a second early TSS) and six patients suffered disease recurrence (mean 39.2 ± 52.4 months). An immediate second TSS induced additional hormonal deficiencies (diabetes insipidus) in three patients with no surgical complications. Persistent disease was noted in nine patients despite three patients having an immediate second TSS. Positive predictive value for remission of cortisol2 mcg/dl and ACTH5 pg/ml was 100%. Cortisol and ACTH levels (at all postoperative time points and at 2 months) were correlated (r = 0.37, P0.001). Nadir serum cortisol of ≤2 mcg/dl and ACTH5 pg/ml predicted remission (P0.005), but no level predicted lack of recurrence. Immediate postoperative ACTH/cortisol did not predict length of remission. No patients with postoperative cortisol10 mcg/dl were observed to have delayed remission; all required additional treatment. There was no significant difference in age, body mass index, tumor size and length of follow-up between postoperative cortisol groups: cortisol ≤2 mcg/dl, cortisol5 mcg/dl and cortisol10 mcg/dl. Immediate postoperative cortisol levels should routinely be obtained in CD patients post TSS, until better tools to identify early remission are available. Immediate repeat TSS could be beneficial in patients with cortisol10 mcg/dl and positive CD pathology: our combined (micro- and macroadenomas) remission rate with this approach was 82.7%. ACTH measurements correlate well with cortisol. However, because no single cortisol or ACTH cutoff value excludes all recurrences, patients require long-term clinical and biochemical follow-up. Further research is needed in this area.

Background: Endoscopic third ventriculostomy (ETV) has become one of the most common neuroendoscopic procedures.Methods: In this article, we will review the major milestones in the history of ETV development from its early use by Walter Dandy to the techniques currently employed with advanced technology.Conclusions: ETV has become an important technique in the armamentarium of the neurosurgeon. From a meager beginning with few applications, our knowledge of long-term outcomes has evolved. ETV has a rich history and more recently, has had a renewed interest in its use. Our current understanding of its indications is growing and is based on a century of development through trial and error.

A 69-year-old female with a history of breast cancer and hypertension presented with a rare case of herpes simplex encephalitis (HSE) isolated to her left parietal lobe. The patient's first biopsy was negative for herpes simplex virus (HSV) I/II antigens, but less than two weeks later, the patient tested positive on repeat biopsy. This initial failure to detect the virus and the similarities between HSE and symptoms of intracranial hemorrhage (ICH) suggests repeat testing for HSV in the presence of ICH. Due to the frequency of patients with extra temporal HSE, a diagnosis of HSE should be more readily considered, particularly when a patient may not be improving and a concrete diagnosis has not been solidified.

Introduction The operating microscope (OM) has become instrumental in aiding surgeons during key microdissection with greater safety and detail. An exoscope offers similar detail with improved functionality and greater implications for live teaching and improved operating room flow. Methods Eleven senior neurosurgery residents and fellows performed unilateral, single-level laminotomies on fresh cadavers using an OM and exoscope. Three attending spine surgeons blinded for the visualization technique used then reviewed and graded each decompression. Data points gathered included time of procedure, grading of decompression (1–5), and complications, including dural tear, nerve root injury, and pars fracture. Results Operative times between the 2 systems were not significantly different (14.9 minutes OM vs. 15.6 minutes exoscope, P = 0.766). Despite high variability between evaluators in assessing complications and adequacy of decompression, there was no significant difference between either system. Postprocedural surveys indicated greater comfort with the exoscope, greater ease of use, and superior teaching potential for the exoscope over the standard OM. Conclusion In our simulated operating room model, an exoscope is a valid alternative to the standard OM that affords the surgeon greater comfort with greater teaching potential while maintaining many of the microscope's benefits.

Acromegaly is associated with serious morbidity and mortality, if not well controlled. Approved somatostatin receptor ligands (SRLs) are a mainstay of medical therapy and exhibit preferential affinity for somatostatin receptor (SSTR) subtype 2. Our objective was to assess whether characteristic features of individual growth hormone (GH)-secreting adenomas at diagnosis, correlated with SRL sensitivity, using defined tumor markers. A retrospective review of 86 consecutive acromegaly surgeries (70 patients) performed between January 2006 and December 2011 was undertaken. Patients with any preoperative medical treatment were excluded. Response to SRL therapy was defined as normalization of insulin-like growth factor 1 (IGF1) and random GH

Incisional cerebrospinal fluid (CSF) leakage after cranial surgery is a significant cause of morbidity due to poor wound healing and infection, meningitis, and pseudomeningocele formation. Many common dural closure techniques, such as sutures, autologous grafts, gelatin or collagen sponges, and fibrin glues, are used to achieve watertight closure, although none are US Food and Drug Administration approved for this use. DuraSeal Dural Sealant System is a polyethylene glycol (PEG) hydrogel approved by the U.S. Food and Drug Administration for obtaining watertight dural closure when applied after standard dural suturing. This multicenter, prospective randomized study further evaluated the safety of a PEG hydrogel compared with common dural sealing techniques.A total of 237 patients undergoing elective cranial surgery at 17 institutions were randomized to dural closure augmented with the PEG hydrogel or a control "standard of care" dural sealing technique after Valsalva maneuver demonstrated an intraoperative nonwatertight dural closure. Data were collected on complications resulting in unplanned postoperative interventions or reoperations, surgical site infections, CSF leaks, and other neurological complications within 30 days. Surgeons also provided data on the ease of use of the dural sealing techniques, as well as preparation and application times.The incidences of neurosurgical complications, surgical site infections, and CSF leaks were similar between treatment and control groups, with no statistically significant difference between the measures. In the PEG hydrogel group (n = 120), the incidence of neurosurgical complications was 5.8% (n = 7), the incidence of surgical site infections was 1.7% (n = 2), and the incidence of CSF leak was 0.8% (n = 1). In the control group (n = 117), the incidence of neurosurgical complications was 7.7% (n = 9), the incidence of surgical site infection was 2.6% (n = 3), and the incidence of CSF leak was 1.7% (n = 2). Sealant preparation time was less than 5 minutes in 96.6% of the PEG hydrogel group compared with 66.4% of controls (P

Object The objective of this study was to retrospectively look at methamphetamine (MA) use in patients with aneurysmal subarachnoid hemorrhage (SAH) to determine if MA use affects clinical presentation and outcomes after aneurysmal SAH. Methods A retrospective review of patients admitted to the Oregon Health & Science University neurosurgical service with aneurysmal SAH during the past 6 years was undertaken. Variables analyzed included MA use, age, sex, cigarette use, Hunt and Hess grade, Fisher grade, admission blood pressure, aneurysm characteristics, occurrence of vasospasm, hospital length of stay (LOS), cerebral infarction, aneurysm treatment, and Glasgow Outcome Scale (GOS) score. Data differences between MA users and nonusers were statistically analyzed using multivariate logistic regression analysis. A separate comparison with randomly selected age-matched nonuser controls was also performed. Results Twenty-eight (7%) of 374 patients with aneurysmal SAH were identified as MA users. Methamphetamine users were younger than nonusers (45.2 vs 55.9 years, respectively; p 15 days included age (p = 0.002), Fisher grade (p = 0.002), Hunt and Hess grade (p Conclusions A history of MA use may predict poorer outcomes in patients who present with aneurysmal SAH. Methamphetamine users have significantly worse presentations and outcomes when compared with age-matched controls.

High-grade dural arteriovenous fistulas (DAVFs) with retrograde cortical leptomeningeal drainage are formidable lesions because of their risk for intracranial hemorrhage. Treatment is aimed at occluding venous outflow to achieve obliteration of the fistula. In DAVFs that involve a large dural venous sinus (transverse sigmoid sinus or superior sagittal sinus), occluding venous outflow can be accomplished endovascularly with transvenous embolization. However, in some cases of DAVFs with reflux into cortical leptomeningeal veins, there may be venous restrictive disease downstream, such as occlusive thrombosis, which can prohibit endovascular access via the transfemoral or transjugular routes. In these instances, a transcranial approach can be performed to expose the large dural venous sinus distal to the site of occlusion for direct catheterization of the venous outflow for transvenous embolization. This combined surgical and endovascular strategy provides direct access to the venous outflow and bypasses the site of thrombotic obstruction.In this report, we describe our technique of single stage surgically-assisted transvenous embolization in three patients with high-grade DAVFs involving a large dural sinus.All patients achieved complete obliteration of their DAVFs without any venous related complications.Our technique of surgically-assisted direct transvenous embolization of high-grade DAVFs can be successfully performed as a single stage in the operating room with intraoperative angiography and stereotactic image guidance.

Object Staged resection of large vestibular schwannomas (VSs) has been proposed as a strategy to improve facial nerve outcomes and morbidity. The authors report their experience with 2-stage resections of large VSs and analyze the indications, facial nerve outcomes, surgical results, and complications. The authors compare these results with those of a similar cohort of patients who underwent a single-stage resection. Methods A retrospective review of all patients (age > 18 years) who underwent surgery from 2002 to 2010 for large (≥ 3 cm) VSs at the authors' institution with a minimum of 6 months follow-up was undertaken. A first-stage retrosigmoid approach (without meatal drilling) was performed to remove the cerebellopontine angle portion of the tumor and to decompress the brainstem. A decision to stage the operation was made intraoperatively if there was cerebellar or brainstem edema, excessive tumor adherence to the facial nerve or brainstem, a poorly stimulating facial nerve, or a thinned or splayed facial nerve. A second-stage translabyrinthine approach was performed at a later date to remove the remaining tumor. The single-stage resection consisted of a retrosigmoid approach with meatal drilling. Patient charts were evaluated for tumor size, extent of resection, tumor recurrence, House-Brackmann facial nerve function grade, and complications. Results Twenty-eight and 19 patients underwent 2- or single-stage resection of a large VS, respectively. The average tumor size was 3.9 cm (range 3.2–7 cm) in the 2-stage group and 3.9 cm (range 3.1–5 cm) in the single-stage group. The mean follow-up was 36 ± 19 months in the 2-stage group versus 24 ± 14 months in the single-stage group. Gross-total or near-total resection was achieved in 27 (96.4%) of 28 patients in the 2-stage group and 15 (79%) of 19 patients in the single-stage group (p < 0.01). Anatomical facial nerve preservation was achieved in all but 1 patient (94.7%), and there were no recurrences on follow-up imaging in the 2-stage group. Good facial nerve functional outcome (House-Brackmann Grades I and II) at last follow-up was achieved in 23 (82%) of 28 patients in the 2-stage group and 10 (53%) of 19 patients in the single-stage group (p < 0.01). Cerebrospinal fluid leak–related complications (intracranial hypotension, blood patch, and lumboperitoneal shunt for pseudomeningocele) were more common in the 2-stage group. There were no postoperative strokes, hemorrhages, or deaths in either group. Conclusions The authors' results suggest that staged resection of large VSs may potentially achieve better facial nerve outcomes. There does not appear to be added neurological morbidity with staged resections.

Object Facial nerve paresis can be a devastating complication following resection of large (> 2.5 cm) cerebellopontine angle (CPA) tumors. The authors have developed and used a new high-density diffusion tensor imaging (HD-DT imaging) method, aimed at preoperatively identifying the location and course of the facial nerve in relation to large CPA tumors. Their study objective was to preoperatively identify the facial nerve in patients with large CPA tumors and compare their HD-DT imaging method with a traditional standard DT imaging method and correlate with intraoperative findings. Methods The authors prospectively studied 5 patients with large (> 2.5 cm) CPA tumors. All patients underwent preoperative traditional standard- and HD-DT imaging. Imaging results were correlated with intraoperative findings. Results Utilizing their HD-DT imaging method, the authors positively identified the location and course of the facial nerve in all patients. In contrast, using a standard DT imaging method, the authors were unable to identify the facial nerve in 4 of the 5 patients. Conclusions The HD-DT imaging method that the authors describe and use has proven to be a powerful, accurate, and rapid method for preoperatively identifying the facial nerve in relation to large CPA tumors. Routine integration of HD-DT imaging in preoperative planning for CPA tumor resection could lead to improved facial nerve preservation.

New criteria that define acromegaly remission are more stringent: normal (age/sex-adjusted) insulin-like growth factor type 1 (IGF-1), growth hormone (GH) random (GHr)

Background After intradural cranial surgery, a dural substitute is often required for dural closure. Although preferred, limitations of autograft include local availability and additional surgical site morbidity. Thus, allografts, xenografts, and synthetics are frequently used. Objective To report 6-month results of a randomized, controlled trial of a biosynthesized cellulose (BSC) composed duraplasty device compared with commercially available dural replacements. Methods A total of 99 patients (62 BSC; 37 control) were treated on protocol, using a 2:1 (BSC:control) blocked randomization schedule. Physical examinations were performed pre- and postoperatively within 10 days and at 1, 3, and 6 months. Magnetic resonance imaging was performed preoperatively and at 6 months. The primary study endpoint was the absence of pseudomeningocele and extracerebral fluid collection confirmed radiographically and the absence of cerebrospinal fluid fistula at 6 months. Results At 6 months, the primary hypothesis, noninferiority of the BSC implant compared with the control group, was confirmed (P = .0206). Overall success was achieved by 96.6% of BSC and 97.1% of control patients. No significant difference was revealed between treatment groups for surgical site infection (P = 1.0000) or wound healing assessment (P ≥ .3685) outcomes, or radiologic endpoints (P ≥ .4061). Device strength and seal quality favored BSC. Conclusion This randomized, controlled trial establishes BSC as noninferior to commercially available dural replacement devices. BSC offers a hypothetical advantage concerning prion and other infectious agent exposure; superior handling qualities are evident. Longer term data are necessary to identify limitations of BSC and its potential equivalence to the gold standard of pericranium.

The intracarotid sodium amobarbital (Amytal) test, the Wada test, remains an efficient test for evaluation of language and memory function. However, due to a world shortage of amobarbital, it has become necessary to investigate the use of alternatives. We report the efficacy of the Wada test using secobarbital sodium (Ional) in determining language dominance. An accurate determination of language dominance was required in 43 patients preoperatively at our institution. Patients underwent the Wada test using secobarbital sodium, effectiveness and safety were assessed. Patients were monitored for vital signs (blood pressure, respiratory rates, heart rates and saturation of oxygen). Ten patients were further monitored for continuous intra-arterial blood pressure and monitored with scalp electroencephalography (EEG). Language dominance was determined by the Wada test with secobarbital sodium in all patients. Total volume of secobarbital sodium injected was 10-25 mg (mean 16.5 ± 3.2 mg). Changes in vital signs were minimal and any induced neurological deficits completely disappeared within 8 min. On EEG records, induced theta waves immediately appeared on the ipsilateral side of the intra-arterial injection and disappeared within 6 min. One patient described a scintillating scotoma (sensation of shimmering light in his eyes) at the moment of injection; another experienced an epileptic episode during the test and recovered after 6 min. No adverse events were observed in the remaining 41 cases. We propose secobarbital sodium as a safe and reliable alternative to sodium amobarbital used in the Wada test to determine language dominance.

Object Convection-enhanced delivery (CED) is a novel intracerebral drug delivery technique with considerable promise for delivering therapeutic agents throughout the CNS. Despite this promise, Phase III clinical trials employing CED have failed to meet clinical end points. Although this may be due to inactive agents or a failure to rigorously validate drug targets, the authors have previously demonstrated that catheter positioning plays a major role in drug distribution using this technique. The purpose of the present work was to retrospectively analyze the expected drug distribution based on catheter positioning data available from the CED arm of the PRECISE trial. Methods Data on catheter positioning from all patients randomized to the CED arm of the PRECISE trial were available for analyses. BrainLAB iPlan Flow software was used to estimate the expected drug distribution. Results Only 49.8% of catheters met all positioning criteria. Still, catheter positioning score (hazard ratio 0.93, p = 0.043) and the number of optimally positioned catheters (hazard ratio 0.72, p = 0.038) had a significant effect on progression-free survival. Estimated coverage of relevant target volumes was low, however, with only 20.1% of the 2-cm penumbra surrounding the resection cavity covered on average. Although tumor location and resection cavity volume had no effect on coverage volume, estimations of drug delivery to relevant target volumes did correlate well with catheter score (p < 0.003), and optimally positioned catheters had larger coverage volumes (p < 0.002). Only overall survival (p = 0.006) was higher for investigators considered experienced after adjusting for patient age and Karnofsky Performance Scale score. Conclusions The potential efficacy of drugs delivered by CED may be severely constrained by ineffective delivery in many patients. Routine use of software algorithms and alternative catheter designs and infusion parameters may improve the efficacy of drugs delivered by CED.

Cerebral spinal fluid (CSF) rhinorrhea immediately after the initiation of cabergoline in prolactinoma patients is an uncommon complication that could lead to serious comorbidities and management difficulties. We present a case of a woman with multiple endocrine neoplasia type 1 syndrome and a recurrent macroprolactinoma, who developed CSF rhinorrhea and pneumocephalus after 3 doses of 0.5 mg cabergoline. The patient was treated for sinusitis after complaining of increasing headache. Imaging revealed a large pituitary tumor, skull base erosion, and pneumocephalus. Skull-base defect repair and subsequent transsphenoidal tumor debulking was performed. Prolactin continued to increase postoperatively, and the dopamine agonist (DA) was changed to bromocriptine, with no further CSF leak during 18 months of follow-up. We recommend urgent surgical repair as the treatment of choice for CSF leak following DA treatment. Concurrent surgical tumor debulking should be preformed if possible. Retreatment with DA is a safe option in most cases. To our knowledge, CSF rhinorrhea following cabergoline therapy has not been described in the multiple endocrine neoplasia type 1 syndrome.

Subfrontal schwannomas, sometimes referred to as olfactory groove schwannomas, are rare tumors (34 cases reported to date). Despite the name and several theories proposed in the literature, there is no officially recognized description of the tumor's cell origin. Yasuda proposed the concept of an olfactory ensheathing cell (OEC) tumor in 2006. Olfactory ensheathing cells are glial cells that ensheath the axons of the first cranial nerve. Microscopically, both olfactory ensheathing cells and Schwann cells have similar morphological and immunohistochemical features. However, immunohistochemically olfactory ensheathing cells are negative for Leu7 and Schwann cells positive. A 30-year-old woman presented with a subfrontal, extraaxial, enhancing tumor, and underwent gross total resection. Immunohistochemical reactivity data suggested a schwannoma (positive for S-100 and negative for epithelial membrane antigen). However, the tumor was negative for Leu7. Accordingly, our final diagnosis was that of an OEC tumor. Subfrontal schwannoma immunohistochemical staining, if negative for Leu7, is indicative of an OEC tumor. It is possible that schwannoma-like extraaxial tumors at the anterior skull base are OEC tumors, which negative Leu7 staining can confirm.

Object The DuraSeal dural sealant system, a polyethylene glycol hydrogel, has been shown to be safe and effective when used with commercial and autologous duraplasty materials. The authors report on the safety and effectiveness of this sealant when used in conjunction with nonautologous duraplasty materials. Methods In this retrospective, nonrandomized, multicenter study, the safety and efficacy of a dural sealant system was assessed in conjunction with primarily collagen-based nonautologous duraplasty materials in a sample of 66 patients undergoing elective cranial procedures at 3 institutions. This cohort was compared with 50 well-matched patients from the DuraSeal Pivotal Trial who were treated with this sealant system and autologous duraplasty material. Results The key end points of the study were the incidences of CSF leaks, surgical site infections, and meningitis 90 days after surgery. The incidence of postoperative CSF leakage was 7.6% in the study group (retrospective population) and 6.0% in the Pivotal Trial population. The incidence of meningitis was 0% and 4.0% in the retrospective and Pivotal Trial groups, respectively. There were no serious device-related adverse events or unanticipated adverse device effects noted for either population. Conclusions This study demonstrates that the DuraSeal sealant system is safe and effective when used for watertight dural closure in conjunction with nonautologous duraplasty materials.

To analyze the interpretation of the 1-microg low-dose adrenocorticotropic hormone (ACTH) test (LDT) for assessment of the presence of adrenal insufficiency (AI) in comparison with the 250-microg or standard high-dose ACTH test (HDT), which uses the same cutoff cortisol value of 18 microg/dL (500 nmol/L) as the lower limit of normal.We present a retrospective review of 26 patients referred to the Pituitary Clinic who underwent both the LDT and the HDT for evaluation of the function of the hypothalamic-pituitary-adrenal axis.Of the 26 study patients, 23 had discordant findings--abnormal LDT and normal HDT results with use of the empiric cortisol cutoff of 18 microg/dL at 30 minutes in response to the ACTH dose. Glucocorticoid replacement therapy was stopped or not started in these patients, and no clinical symptoms of AI developed during a follow-up period ranging from 19 to 24 months.Our retrospective review of patients' discordant LDT and HDT results questions the reliability of the LDT as a screening test for AI, as currently interpreted. Our data suggest that abnormal results should be evaluated in the context of the clinical picture and that additional testing may be indicated to prevent unwarranted treatment with glucocorticoids. Further studies are needed to establish a safe, sensitive, and specific test for the diagnosis of AI.

Object In this study, the authors evaluated the efficacy and safety of modified orbitozygomatic craniotomy for resection of craniopharyngioma in children. Methods A prospective, institutional review board–approved database was retrospectively reviewed for pediatric patients undergoing craniopharyngioma resection performed by a single surgeon. Results Ten patients underwent craniopharyngioma resection surgery between July 2000 and January 2006 (4 girls and 6 boys, ages 1.5–17 years). Nine patients presented to the authors' institution, and 1 patient was referred after surgery and radiation therapy were administered elsewhere. Nine patients presented with visual field deficits (2 with unilateral or bilateral light perception only) and 5 with endocrine dysfunction. Eight patients had large tumors that significantly displaced the optic chiasm and hypothalamus. All patients underwent a modified frontotemporal orbitozygomatic osteotomy in a single piece. The lamina terminalis was opened in 4 patients with third ventricular extension. One patient required a staged transsphenoidal operation to remove residual tumor in the sella turcica, and 1 patient underwent a contralateral subtemporal approach to resect a daughter lesion in the prepontine cistern. Complete radiographic resection was achieved in all patients. Follow-up averaged 55 months (range 12–95 months). Vision was improved in 8 patients and remained stable in 2. All patients had postoperative endocrine dysfunction. One patient experienced transient cranial nerve IV palsy and 1 suffered a small caudate stroke 5 months after surgery without sequelae. Two patients experienced polyphagia and weight gain without other symptoms of hypothalamic dysfunction. There were no other new neurological deficits. Conclusions Modified orbitozygomatic craniotomy provides excellent exposure of the suprasellar region with minimal brain retraction, allowing complete resection of craniopharyngiomas with good visual and neurological results.

Object Surgical intervention may be required if endovascular embolization is insufficient to completely obliterate intracranial dural arteriovenous fistulas (DAVFs). The authors report their 14-year experience with 23 patients harboring diverse intracranial DAVFs that required surgical intervention. Methods Between 1993 and 2007, 23 patients underwent surgery for intracranial DAVFs. The following types of DAVFs were treated: superior petrosal sinus (in 10 patients); parietooccipital (in 3); confluence of sinuses and ethmoidal (in 2 each); and tentorial, falcine, occipital, transverse-sigmoid, superior sagittal, and cavernous sinuses (in 1 patient each). In all cases, the authors' goal was to obliterate the DAVF venous outflow by direct surgical interruption of the leptomeningeal venous drainage. Transarterial embolization was used primarily as an adjunct to decrease flow to the DAVF prior to definitive treatment. Results Complete angiographic obliteration of the DAVF was achieved in all cases. There were no complications of venous hypertension, venous infarction, or perioperative death. There were no recurrences and no further clinical events (new hemorrhages or focal neurological deficits) after a mean follow-up of 45 months. Conclusions The authors' experience emphasizes the importance of occluding venous outflow to obliterate intracranial DAVFs. Those that drain purely through leptomeningeal veins can be safely obliterated by surgically clipping the arterialized draining vein as it exits the dura. Radical excision of the fistula is not necessary.

Object Pituitary adenomas represent a large proportion of brain tumors that are increasing in incidence because of improved imaging techniques. Headache is the primary symptom in patients with large tumors (macroadenomas), but is also a symptom in patients with small tumors (microadenomas, tumors < 1.0 cm). The prevalence and optimal treatment of headaches associated with pituitary tumors is still unclear, particularly in cases of microadenoma. If conventional medical management fails, transsphenoidal surgery (TSS) may be considered as an alternative treatment for intractable headaches. Methods The authors conducted a retrospective review of 512 patients who underwent TSS at Oregon Health & Science University between 2001 and 2007; patients with Cushing disease were excluded. The authors identified 41 patients with small pituitary tumors who underwent TSS, and retrospectively evaluated the resolution and/or treatment of headache. Results Ninety percent of patients who presented with nonfunctioning microadenomas and Rathke cleft cysts experienced resolution or improvement in their headaches after TSS, and 56% of patients who presented with hyperfunctioning pituitary microadenomas had improvement in their headaches. There were no postoperative complications. Conclusions In this retrospective study, the authors demonstrate the efficacy of TSS in the treatment of intractable headaches in patients who present with pituitary microadenomas (nonsecreting and hypersecretory) and Rathke cleft cysts.

Background: The following technical case report illustrates the use of multiple imaging modalities including 3D CTV with frameless stereotactic navigation for intraoperative planning and localization for surgical obliteration of a cranial dAVF with leptomeningeal drainage. Case Description: This 65-year-old man presented with an asymptomatic occipital dAVF with leptomeningeal drainage. In addition to cerebral angiography, a CTV with 3D reconstruction was performed, which provided excellent visualization of the dAVF and clarified its pattern of drainage. The dAVF was supplied by a middle meningeal artery branch that drained into an occipital cortical vein, which then retrograde filled the vein of Labbe. Frameless stereotactic navigation with the imported CTV images was used to plan the craniotomy and to localize the leptomeningeal draining vein and vein of Labbe. The draining vein of the fistula was successfully ligated and divided while preserving flow in the vein of Labbe. Postoperative angiogram demonstrated complete obliteration of the dAVF. Conclusion: Integration of a 3D reconstructed CTV with conventional angiographic information optimized our surgical understanding of the spatial anatomy of this dAVF and its pattern of venous drainage. Applying the CTV with frameless stereotaxy allowed for safe obliteration of the dAVF while preserving the vein of Labbe.

The formation of the occipital bone is intricate and has been extensively studied with many controversial conclusions, but with minimal effort being focused on the genes and molecular interactions necessary for its formation. A better understanding of this bone of the calvarial and skull base may shed light on pathologies where the occiput is often considered the offending entity. A review of the germane medical literature using textbooks and standard search engines was performed to gather information about previous conclusions as it pertains to the embryology and ossification of the occipital bone. The occipital bone has both membranous and cartilaginous origin with ossification occurring as early as week 9 of fetal gestation. Its formations is dependent on complex interacts between genes and molecules with pathologies resulting from disruption of this delicate process. There has been much controversy in the past in regards to the development and ossification process necessary for occipital bone formation, which has only recently been clarified with documentation of the genes and molecular interactions necessary for its formation. Lastly, this improved knowledge might improve our understanding of such congenital derailments as the Chiari malformations.

An understanding of normal CSF physiology is a prerequisite to treating problems such as CSF fistulae and pseudomeningoceles. CSF diversion techniques fall into two categories, external and internal. External lumbar drainage is useful when temporary CSF diversion is necessary (eg, in cases necessitating manipulation and retraction of the brain to gain access to deep lesions) and in treating otorrhea or rhinorrhea following traumatic or iatrogenic insults to the cranial base. Drawbacks include insertion discomfort and limited duration of therapy.LP and VP shunts came into widespread use in the 1970s, and both systems share risks of bowel perforation, obstruction, over drainage and wound-related complications. In addition, VP shunts add the risks of intracerebral hematoma and ventriculitis. New valve technology has made it possible to alter the volume drained, thus alleviating problems of over-and under drainage.

✓ The authors report on a surgical technique involving a one-piece osteoplastic bone flap, which incorporates the frontal, temporal, and lateral portions of the orbital rim as a technically simpler alternative to the standard orbitozygomatic (OZ) craniotomy. The orbital rim component extends just laterally from the supraorbital foramen/notch to the frontozygomatic suture. This craniotomy obviates the need for removing the zygoma and has evolved from the authors' experience in more than 200 patients with a variety of pathological lesions, both vascular and tumorous. The osteoplastic aspect of this technique was initially evaluated in 14 cadaveric sites in seven heads dissected prior to implementing this procedure clinically. The osteoplastic bone flap minimally obstructs the surgical view and provides all the advantages of a standard OZ craniotomy. Temporalis muscle atrophy leading to temporal hollowing is avoided, a bone union to the calvaria is improved, and the possibility of bone infection is decreased. The osteoplastic component of the technique adds to the improved long-term cosmesis and warrants active consideration in the art of neurosurgery.

✓ The authors present a modification to a previously reported supraorbital craniotomy procedure that is smaller, simpler, safe, and cosmetically pleasing. Minimal brain retraction is used without compromising the surgical exposure of the orbital roof, floor of the anterior fossa, and the parasellar region to treat tumoral lesions that are located medial to the ipsilateral optic nerve as well as aneurysms of the anterior communicating artery.

Object. Conventional wisdom regarding skull base surgery says that more extensive bone removal equals greater exposure. Few researchers have quantitatively examined this assertion, however. In this study the authors used a frameless stereotactic system to measure quantitatively the area of petroclival exposure and surgical freedom for manipulation of instruments with successive steps of temporal bone removal. Methods. With the aid of high-power magnification and a high-speed drill, 12 cadaveric specimens were dissected in four predetermined, successive bone removal steps: 1) removal of the Kawase triangle; 2) removal of the Glasscock triangle; 3) removal of the cochlea together with skeletonization of the anterior internal auditory canal; and 4) inferior displacement of the zygoma. Step 1 offered 62 ± 43 mm2 of exposed petroclival area, with 84 ± 69 mm2 of surgical freedom; Step 2, 61 ± 22 and 76 ± 58 mm2; Step 3, 128 ± 47 and 109 ± 87 mm2; and Step 4, 135 ± 38 and 102 ± 69 mm2, respectively. Conclusions. The middle fossa approach provided a means surgically to expose the petroclival area. When examined quantitatively by using a frameless stereotactic device, the authors determined that the removal of the cochlea and skeletonization of the anterior internal auditory canal (Step 3) provided the most significant increase in both exposure and surgical freedom. Removal of the zygoma improved neither exposure nor surgical freedom.

Despite recent advances in the treatment of malignant gliomas (World Health Organization grade III and grade IV tumors- Glioblastoma Multiforme, Anaplastic Astrocytoma and Anaplastic Oligodendroglioma), the overall prognosis remains poor. Tumor recurrence in malignant glioma is inevitable, and associated with reduced overall survival (OS). Bevacizumab is approved for use in progressive GBM as a second line treatment, and is associated with improvements in progression free survival (PFS). However, all GBM patients eventually recur on bevacizumab therapy, with a very short OS after bevacizumab failure. No FDA-approved therapy is available for this clinical setting. Etoposide crosses the blood-brain barrier and has activity in recurrent malignant gliomas. The use of bevacizumab with etoposide in recurrent malignant gliomas in the setting of bevacizumab resistance is evaluated in this review. Bevacizumab and etoposide combined therapy is associated with radiographic response and effectiveness in selected patients.

The outcomes of surgery for acoustic neuromas have improved dramatically since the development of modern surgical techniques, the operating microscope, magnetic resonance imaging (MRI), and cranial nerve monitoring. The goals of acoustic neuroma surgery are now preservation of facial nerve function and, when feasible, hearing preservation. Many large series do not report standardized hearing and facial function grading, and they include patients who did not benefit from the most modern techniques. The purpose of this study was to present the results of acoustic neuroma surgery using the most modern techniques and equipment, using standardized grading systems.Retrospective review.Tertiary referral center.97 patients who underwent surgical removal of acoustic neuromas from 1992 to 1998.All patients underwent acoustic neuroma surgery and had preoperative audiograms and MRI with contrast. In addition, all patients had preoperative and postoperative facial function graded by the House-Brackmann scale and intraoperative facial nerve monitoring. Hearing preservation was attempted in patients with tumors of any size who had preoperative function of grade A or B according to the Committee on Hearing and Equilibrium guidelines for reporting results of acoustic neuroma surgery.Hearing preservation was considered successful if the patient retained serviceable hearing grade A or B. House-Brackmann grade 1 or 2 was considered excellent facial function. Complications were recorded.Facial nerve integrity was preserved in 96 of 97 patients (99%). Eight of 8 (100%) patients with intracanalicular tumors had excellent facial nerve function (HB 1-2). Fifty-two of 55 (95%) of patients with small tumors had excellent facial nerve function, and 15 of 24 (63%) with medium tumors had HB grade 1-2. Hearing was preserved in 29% of patients with tumors under 2 cm. The overall complication rate was 20%; cerebrospinal fluid leak was the most common.These results show that with modern imaging and surgical techniques, acoustic neuroma surgery is extremely safe and outcomes are very good. Surgery remains the treatment of choice for most tumors until alternative therapies, such as gamma knife, use uniform grading scales and show long-term facial and hearing results.

Object. The petrosal approach to the petroclival region has been used by a variety of authors in various ways and the terminology has become quite confusing. A systematic assessment of the benefits and limitations of each approach is also lacking. The authors classify their approach to the middle and upper clivus, review the applications for each, and test their hypotheses on a cadaver model by using frameless stereotactic guidance.Methods. The petrosal approach to the upper and middle clivus is divided into four increasingly morbidity-producing steps: retrolabyrinthine, transcrusal (partial labyrinthectomy), transotic, and transcochlear approaches. Four latexinjected cadaveric heads (eight sides) underwent dissection in which frameless stereotactic guidance was used. An area of exposure 10 cm superficial to a central target (working area) was calculated. The area and length of clival exposure with each subsequent dissection was also calculated.The retrolabyrinthine approach spares hearing and facial function but provides for only a small window of upper clival exposure. The view afforded by what we have called the transcrusal approach provides for up to four times this exposure. The transotic and transcochlear procedures, although producing more morbidity, add little in terms of a larger clival window. However, with each step, the surgical freedom for manipulation of instruments increases.Conclusions. The petrosal approach to the upper and middle clivus is useful but should be used judiciously, because levels of morbidity can be high. The retrolabyrinthine approach has limited utility. For tumors without bone invasion, the transcrusal approach provides a much more versatile exposure with an excellent chance of hearing and facial nerve preservation. The transotic approach provides for greater versatility in treating lesions but clival exposure is not greatly enhanced. Transcochlear exposure adds little in terms of intradural exposure and should be reserved for cases in which access to the petrous carotid artery is necessary.

Object. The purpose of this study was to evaluate the far-lateral transcondylar transtubercular approach (complete FLA) based on quantitative measurements of the exposure of the foramen magnum and petroclival area obtained after each successive step of this approach.Methods. The complete FLA was reproduced in eight specially prepared cadaveric heads (a total of 15 sides). The approach was divided into six steps: 1) C-1 hemilaminectomy and suboccipital craniectomy with unroofing of the sigmoid sinus (basic FLA); 2) partial resection of the occipital condyle (up to the hypoglossal canal); 3) removal of the jugular tuberculum; 4) mastoidectomy (limited to the labyrinth and the fallopian canal) and retraction of the sigmoid sinus; 5) resection of the lateral mass of C-1 with mobilization of the vertebral artery; and 6) resection of the remaining portion of the occipital condyle. After each successive step, a standard set of measurements was obtained using a frameless stereotactic device. The measurements were used to estimate two parameters: the size of the exposed petroclival area and the size of a spatial cone directed toward the anterior rim of the foramen magnum, which depicts the amount of surgical freedom available for manipulation of instruments.The initial basic FLA provided exposure of only 21 ± 6% of the petroclival area that was exposed with the full, six-step maximally aggressive (complete) FLA. Likewise, only 18 ± 9% of the final surgical freedom was obtained after the basic FLA was performed. Each subsequent step of the approach increased both petroclival exposure and surgical freedom. The most dramatic increase in petroclival exposure was noted after removal of the jugular tuberculum (71 ± 12% of final exposure), whereas the least improvement in exposure occurred after the final step, which consisted of total condyle resection.Conclusions. The complete FLA provides wide and sufficient exposure of the foramen magnum and lower to middle clivus. The complete FLA consists of several steps, each of which contributes to increasing petroclival exposure and surgical freedom. However, the FLA may be limited to the less aggressive steps, while still achieving significant exposure and surgical freedom. The choice of complete or basic FLA thus depends on the underlying pathological condition and the degree of exposure required for effective surgical treatment.