Evaluation of Surgical Resection Goal and Its Relationship to Extent of Resection and Patient Outcomes in a Multicenter Prospective Study of Patients With Surgically Treated, Nonfunctioning Pituitary Adenomas: A Case Series.

BACKGROUND: The influence of the surgeon's preoperative goal regarding the extent of tumor resection on patient outcomes has not been carefully studied among patients with nonfunctioning pituitary adenomas. OBJECTIVE: To analyze the relationship between surgical tumor removal goal and patient outcomes in a prospective multicenter study. METHODS: Centrally adjudicated extent of tumor resection (gross total resection [GTR] and subtotal resection [STR]) data were analyzed using standard univariate and multivariable analyses. RESULTS: GTR was accomplished in 148 of 171 (86.5%) patients with planned GTR and 32 of 50 (64.0%) patients with planned STR (P = .001). Sensitivity, specificity, positive predictive value, and negative predictive value of GTR goal were 82.2, 43.9, 86.5, and 36.0%, respectively. Knosp grade 0-2, first surgery, and being an experienced surgeon were associated with surgeons choosing GTR as the goal (P < .01). There was no association between surgical goal and presence of pituitary deficiency at 6 mo (P = .31). Tumor Knosp grade (P = .004) and size (P = .001) were stronger predictors of GTR than was surgical goal (P = .014). The most common site of residual tumor was the cavernous sinus (29 of 41 patients; 70.1%). CONCLUSION: This is the first pituitary surgery study to examine surgical goal regarding extent of tumor resection and associated patient outcomes. Surgical goal is a poor predictor of actual tumor resection. A more aggressive surgical goal does not correlate with pituitary gland dysfunction. A better understanding of the ability of surgeons to meet their expectations and of the factors associated with surgical result should improve prognostication and preoperative counseling.

Results of a prospective multicenter controlled study comparing surgical outcomes of microscopic versus fully endoscopic transsphenoidal surgery for nonfunctioning pituitary adenomas: the Transsphenoidal Extent of Resection (TRANSSPHER) Study.

OBJECTIVE: Many surgeons have adopted fully endoscopic over microscopic transsphenoidal surgery for nonfunctioning pituitary tumors, although no high-quality evidence demonstrates superior patient outcomes with endoscopic surgery. The goal of this analysis was to compare these techniques in a prospective multicenter controlled study. METHODS: Extent of tumor resection was compared after endoscopic or microscopic transsphenoidal surgery in adults with nonfunctioning adenomas. The primary end point was gross-total tumor resection determined by postoperative MRI. Secondary end points included volumetric extent of tumor resection, pituitary hormone outcomes, and standard quality measures. RESULTS: Seven pituitary centers and 15 surgeons participated in the study. Of the 530 patients screened, 260 were enrolled (82 who underwent microscopic procedures, 177 who underwent endoscopic procedures, and 1 who cancelled surgery) between February 2015 and June 2017. Surgeons who used the microscopic technique were more experienced than the surgeons who used the endoscopic technique in terms of years in practice and number of transsphenoidal surgeries performed (p < 0.001). Gross-total resection was achieved in 80.0% (60/75) of microscopic surgery patients and 83.7% (139/166) of endoscopic surgery patients (p = 0.47, OR 0.8, 95% CI 0.4-1.6). Volumetric extent of resection, length of stay, surgery-related deaths, and unplanned readmission rates were similar between groups (p > 0.2). New hormone deficiency was present at 6 months in 28.4% (19/67) of the microscopic surgery patients and 9.7% (14/145) of the endoscopic surgery patients (p < 0.001, OR 3.7, 95% CI 1.7-7.7). Microscopic surgery cases were significantly shorter in duration than endoscopic surgery cases (p < 0.001). CONCLUSIONS: Experienced surgeons who performed microscopic surgery and less experienced surgeons who performed endoscopic surgery achieved similar extents of tumor resection and quality outcomes in patients with nonfunctioning pituitary adenomas. The endoscopic technique may be associated with lower rates of postoperative pituitary gland dysfunction. This study generally supports the transition to endoscopic pituitary surgery when the procedure is performed by proficient surgeons, although both techniques yield overall acceptable surgical outcomes.■ CLASSIFICATION OF EVIDENCE Type of question: therapeutic; study design: prospective cohort trial; evidence: class III.Clinical trial registration no.: NCT02357498 (clinicaltrials.gov).

Proposal and Validation of a Simple Grading Scale (TRANSSPHER Grade) for Predicting Gross Total Resection of Nonfunctioning Pituitary Macroadenomas After Transsphenoidal Surgery.

BACKGROUND: A simple, reliable grading scale to better characterize nonfunctioning pituitary adenomas (NFPAs) preoperatively has potential for research and clinical applications. OBJECTIVE: To develop a grading scale from a prospective multicenter cohort of patients that accurately and reliably predicts the likelihood of gross total resection (GTR) after transsphenoidal NFPA surgery. METHODS: Extent-of-resection (EOR) data from a prospective multicenter study in transsphenoidal NFPA surgery were analyzed (TRANSSPHER study; ClinicalTrials.gov NCT02357498). Sixteen preoperative radiographic magnetic resonance imaging (MRI) tumor characteristics (eg, tumor size, invasion measures, tumor signal characteristics, and parameters impacting surgical access) were evaluated to determine EOR predictors, to calculate receiver-operating characteristic curves, and to develop a grading scale. A separate validation cohort (n = 165) was examined to assess the scale's performance and inter-rater reliability. RESULTS: Data for 222 patients from 7 centers treated by 15 surgeons were analyzed. Approximately one-fifth of patients (18.5%; 41 of 222) underwent subtotal resection (STR). Maximum tumor diameter > 40 mm; nodular tumor extension through the diaphragma into the frontal lobe, temporal lobe, posterior fossa, or ventricle; and Knosp grades 3 to 4 were identified as independent STR predictors. A grading scale (TRANSSPHER grade) based on a combination of these 3 features outperformed individual variables in predicting GTR (AUC, 0.732). In a validation cohort, the scale exhibited high sensitivity and specificity (AUC, 0.779) and strong inter-rater reliability (kappa coefficient, 0.617). CONCLUSION: This simple, reliable grading scale based on preoperative MRI characteristics can be used to better characterize NFPAs for clinical and research purposes and to predict the likelihood of achieving GTR.

Visual Field Outcome Reporting in Neurosurgery: Lessons Learned from a Prospective, Multicenter Study of Transsphenoidal Pituitary Surgery.

OBJECTIVE: Visual field (VF) outcomes are commonly reported in neurosurgical case series; however, substantial variability can exist in VF testing and outcome reporting. We aimed to evaluate the challenges of VF testing and to develop detailed recommendations for VF outcome reporting by analyzing results from an ongoing, multicenter study of transsphenoidal pituitary surgery. METHODS: VF testing results were collected during a prospective, multicenter clinical trial evaluating patient outcomes after transsphenoidal surgery for nonfunctioning pituitary adenomas (TRANSSPHER). Two independent ophthalmologists reviewed reliability and outcomes of all VF studies. Preoperative and postoperative VF studies were evaluated individually and as preoperative/postoperative pairs. RESULTS: Suboptimal perimetry field settings were reported in 37% of VF studies. Automated reliability criteria flagged 25%-29% of VF studies as unreliable, whereas evaluation by 2 independent ophthalmologists flagged 16%-28%. Agreement between automated criteria and raters for VF reliability was inconsistent (κ coefficients = 0.55-0.83), whereas agreement between the 2 raters was substantial to almost perfect (κ coefficients = 0.78-0.83). Most patients demonstrated improvement after surgery (rater 1, 67%; rater 2, 60%), with substantial rater agreement on outcomes for paired examinations (κ coefficient = 0.62). CONCLUSIONS: VF outcome studies demonstrated significant variability of test parameters and patient performance. Perimetry field settings varied among patients and for some patients varied preoperatively versus postoperatively. Reliance on automated criteria alone could not substitute for independent ophthalmologist review of test reliability. Standardized guidelines for VF data collection and reporting could increase reliability of results and allow better comparisons of outcomes in future studies.

Dynamics of postoperative serum cortisol after transsphenoidal surgery for Cushing's disease: implications for immediate reoperation and remission.

OBJECTIVESuccessful transsphenoidal surgery for adrenocorticotropin hormone (ACTH)-producing pituitary tumors is associated with subnormal postoperative serum cortisol levels, which may guide decisions regarding immediate reoperation. However, little is known about the detailed temporal course of changes in serum cortisol in the immediate postoperative period, and the relationship of postoperative cortisol dynamics to remission and late recurrence.METHODSA single-center retrospective cohort analysis was performed for all patients undergoing pituitary surgery from 2007 through 2015. Standardized diagnostic and treatment algorithms were applied to all patients with potential Cushing's disease (CD), including microsurgical transsphenoidal adenomectomy (TSA) by a single surgeon. All patients had serum cortisol levels drawn at 6-hour intervals for 72 hours after surgery, and were offered reoperation within 3 days for normal or supranormal postoperative cortisol levels. Primary outcomes were 6-month remission and late recurrence; secondary outcomes were persistent postoperative hypocortisolism and surgical morbidity. Discriminatory levels of postoperative serum cortisol for predicting remission were calculated at various intervals after surgery using receiver operating characteristic (ROC) curves.RESULTSAmong 89 patients diagnosed with CD, 81 underwent initial TSA for a potentially curable lesion; 23 patients (25.8%) underwent an immediate second TSA. For the entire cohort, 6-month remission was achieved in 77.8% and late recurrences occurred in 9.5%, at a mean of 43.5 months. Compared with patients with a single surgery, those with an immediate second TSA had similar rates of remission (78.3% vs 77.6%) and late recurrence (5.6% vs 11.1%). The rate of hypocortisolism for patients with 2 surgeries (12/23, 52.2%) was significantly greater than that for patients with single surgeries (13/58, 22.4%; p < 0.001). There was no difference in the incidence of CSF leaks between the first and second operations. Remission was achieved in 58 (92.1%) of 64 patients who completed the 2-surgery protocol. The temporal course of postoperative serum cortisol levels among patients varied considerably, with subnormal nadir levels < 2 µg/dl occurring between 12 hours and 66 hours. Patients achieving remission had significantly lower mean serum cortisol levels at every time point after surgery (p < 0.01). By ROC curve analysis, nadir cortisol levels < 2.1 µg/dl were predictive of 6-month remission for the entire cohort over 3 days (positive predictive value [PPV] = 94%); discriminating cortisol levels for predicting remission on postoperative day (POD) 2 were < 5.4 µg/dl (PPV = 97%), although patients with remission after postoperative cortisol levels of 2-5 µg/dl had a significantly higher rate of late recurrence.CONCLUSIONSThere is substantial variation in the temporal course of serum cortisol levels over the first 72 hours after TSA for CD, with nadir levels predictive for remission occurring as late as POD 3. Although a cortisol level of 2.1 µg/dl at any point was an accurate predictor of 6-month remission, levels less than 5.4 µg/dl on POD 2 were reasonably accurate. These data may enable decisions regarding the efficacy of an immediate second surgical procedure performed during the same hospitalization; immediate reoperation is associated with excellent remission rates and low recurrence rates in patients otherwise unlikely to achieve remission, but carries a higher risk of permanent hypocortisolism.

Shunt scissors: technical note.

OBJECTIVEWhen performing ventriculoperitoneal shunt surgery it is necessary to create a subgaleal pocket that is of sufficient size to accommodate a shunt valve. In most cases the valve is placed over the posterior skull where the galea begins to transition to suboccipital neck fascia. Dense fibrous attachments in this region of the skull make it technically awkward to develop the subgaleal valve pocket using standard scissors and a blunt dissection technique. In this report the authors describe a new device that enables surgeons to create the shunt valve pocket by using a simple semi-sharp dissection technique.METHODSThe authors analyzed the deficiencies of the standard valve pocket dissection technique and designed shunt scissors that address the identified shortcomings. These new scissors allow the surgeon to sharply dissect the subgaleal space by using an efficient hand-closing maneuver.RESULTSStandard surgical scissors were modified to create shunt scissors that were tested on the benchtop and used in the operating room. In all cases the shunt scissors proved easy to use and allowed the efficient and reliable creation of a subgaleal valve pocket in a technically pleasing manner.CONCLUSIONSShunt scissors represent an incremental technical advance in the field of neurosurgical shunt operations.

Preoperative relative cerebral blood volume analysis in gliomas predicts survival and mitigates risk of biopsy sampling error.

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 < 0.0001) and the hazard ratio for each increase in 1.0 rCBV units was 1.12 (p < 0.002). Additionally, 3 of 13 (23%) patients initially diagnosed by biopsy were upgraded on subsequent resection. Preoperative rCBV was elevated at least one standard deviation above the mean in the 3 upgraded patients, suggestive of undergrading, but not in the ten concordant diagnoses. In conclusion, rCBV can predict overall survival similarly to pathologically determined WHO grade in patients with gliomas. Discordant rCBV analysis and histopathology may help identify patients at higher risk for undergrading.

A case series of atypical features of patients with biopsy-proven isolated IgG4-related hypophysitis and normal serum IgG4 levels.

BACKGROUND: 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. PURPOSE AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Dynamic susceptibility contrast and dynamic contrast-enhanced MRI characteristics to distinguish microcystic meningiomas from traditional Grade I meningiomas and high-grade gliomas.

OBJECTIVE Microcystic meningioma (MM) is a meningioma variant with a multicystic appearance that may mimic intrinsic primary brain tumors and other nonmeningiomatous tumor types. Dynamic susceptibility contrast (DSC) and dynamic contrast-enhanced (DCE) MRI techniques provide imaging parameters that can differentiate these tumors according to hemodynamic and permeability characteristics with the potential to aid in preoperative identification of tumor type. METHODS The medical data of 18 patients with a histopathological diagnosis of MM were identified through a retrospective review of procedures performed between 2008 and 2012; DSC imaging data were available for 12 patients and DCE imaging data for 6. A subcohort of 12 patients with Grade I meningiomas (i.e., of meningoepithelial subtype) and 54 patients with Grade IV primary gliomas (i.e., astrocytomas) was also included, and all preoperative imaging sequences were analyzed. Clinical variables including patient sex, age, and surgical blood loss were also included in the analysis. Images were acquired at both 1.5 and 3.0 T. The DSC images were acquired at a temporal resolution of either 1500 msec (3.0 T) or 2000 msec (1.5 T). In all cases, parameters including normalized cerebral blood volume (CBV) and transfer coefficient (kTrans) were calculated with region-of-interest analysis of enhancing tumor volume. The normalized CBV and kTrans data from the patient groups were analyzed with 1-way ANOVA, and post hoc statistical comparisons among groups were conducted with the Bonferroni adjustment. RESULTS Preoperative DSC imaging indicated mean (± SD) normalized CBVs of 5.7 ± 2.2 ml for WHO Grade I meningiomas of the meningoepithelial subtype (n = 12), 4.8 ± 1.8 ml for Grade IV astrocytomas (n = 54), and 12.3 ± 3.8 ml for Grade I meningiomas of the MM subtype (n = 12). The normalized CBV measured within the enhancing portion of the tumor was significantly higher in the MM subtype than in typical meningiomas and Grade IV astrocytomas (p < 0.001 for both). Preoperative DCE imaging indicated mean kTrans values of 0.49 ± 0.20 min-1 in Grade I meningiomas of the meningoepithelial subtype (n = 12), 0.27 ± 0.12 min-1 for Grade IV astrocytomas (n = 54), and 1.35 ± 0.74 min-1 for Grade I meningiomas of the MM subtype (n = 6). The kTrans was significantly higher in the MM variants than in the corresponding nonmicrocystic Grade 1 meningiomas and Grade IV astrocytomas (p < 0.001 for both). Intraoperative blood loss tended to increase with increased normalized CBV (R = 0.45, p = 0.085). CONCLUSIONS An enhancing cystic lesion with a normalized CBV greater than 10.3 ml or a kTrans greater than 0.88 min-1 should prompt radiologists and surgeons to consider the diagnosis of MM rather than traditional Grade I meningioma or high-grade glioma in planning surgical care. Higher normalized CBVs tend to be associated with increased intraoperative blood loss.

Treatment of Aggressive Prolactin-Secreting Pituitary Adenomas with Adjuvant Temozolomide Chemotherapy: A Review.

Most prolactin-secreting pituitary adenomas demonstrate slow growth and are effectively managed with medical/surgical therapy. Rarely, these tumors can behave aggressively with rapid growth and invasion of local tissues, and are refractory to medical, surgical, or radio-surgical therapies. We report a case of a prolactin-secreting adenoma in a young woman, which became progressively aggressive and refractory to usual treatment modalities, but responded to treatment with the chemotherapeutic agent temozolomide. In addition, we review the literature for treatment of refractory adenomas with temozolomide. The clinical and pathologic characteristics of aggressive prolactin-secreting adenomas are reviewed, as well as their response to dopamine agonists, surgery, radiotherapy, and chemotherapy.

Delayed postoperative hyponatremia after transsphenoidal surgery: prevalence and associated factors.

OBJECT: Transient delayed postoperative hyponatremia (DPH) after transsphenoidal surgery (TSS) is common and can have potentially devastating consequences. However, the true prevalence of transient symptomatic and asymptomatic DPH has not been studied in a large patient cohort with close and accurate follow-up. METHODS: A retrospective analysis of a single-institution prospective database was conducted; all patients undergoing TSS for lesions involving the pituitary gland were followed up in a multidisciplinary neuroendocrine clinic, and demographic, imaging, and clinical data were prospectively collected. Patients were examined preoperatively and followed up postoperatively in a standardized fashion, and their postoperative sodium levels were measured at Weeks 1 and 2 postoperatively. Levels of hyponatremia were rated as mild (serum sodium concentration 130-134 mEq/L), moderate (125-129 mEq/L), or severe (< 125 mEq/L). Routine clinical questionnaires were administered at all postoperative office visits. Postoperative hyponatremia was analyzed for correlations with demographic and clinical features and with immediate postoperative physiological characteristics. RESULTS: Over a 4-year interval, 373 procedures were performed in 339 patients who underwent TSS for sellar and parasellar lesions involving the pituitary gland. The mean (± SD) age of patients was 48 ± 18 years; 61.3% of the patients were female and 46.1% were obese (defined as a body mass index [BMI] ≥ 30). The overall prevalence of DPH within the first 30 days postoperatively was 15.0%; 7.2% of the patients had mild, 3.8% moderate, and 3.8% severe hyponatremia. The incidence of symptomatic hyponatremia requiring hospitalization was 6.4%. The Fisher exact test detected a statistically significant association of DPH with female sex (p = 0.027) and a low BMI (p = 0.001). Spearman rank correlation detected a statistically significant association between BMI and nadir serum sodium concentration (r = 0.158, p = 0.002) and an inverse association for age (r = -0.113, p = 0.031). Multivariate analyses revealed a positive correlation between postoperative hyponatremia and a low BMI and a trend toward association with age; there were no associations between other preoperative demographic or perioperative risk factors, including immediate postoperative alterations in serum sodium concentration. Patients were treated with standardized protocols for hyponatremia, and DPH was not associated with permanent morbidity or mortality. CONCLUSIONS: Delayed postoperative hyponatremia was a common result of TSS; a low BMI was the only clear predictor of which patients will develop DPH. Alterations in immediate postoperative sodium levels did not predict DPH. Therefore, an appropriate index of suspicion and close postoperative monitoring of serum sodium concentration should be maintained for these patients, and an appropriate treatment should be undertaken when hyponatremia is identified.

Intracranial sebaceous neoplasm: a case report.

BACKGROUND AND IMPORTANCE: Sebaceous neoplasms range from hyperplastic hamartomas to malignant tumors and are most commonly cutaneous lesions. We describe the first reported case of an intracranial sebaceous neoplasm, discussing the differential diagnosis and possible pathogenesis in relation to the current literature. CLINICAL PRESENTATION: A 58-year-old man presented with evolving neck stiffness, facial pain, and progressively worsening diplopia. Magnetic resonance imaging identified a moderate-sized lesion intimately related to the left cavernous sinus, which had extended into the posterior fossa. The patient underwent endoscopic, transnasal subtotal resection of the neoplasm with significant improvement. Histologically, the tumor was identified as a sebaceous neoplasm previously unreported intracranially. Follow-up imaging at 6 months revealed no further recurrence. CONCLUSION: This is the first reported case of an intracranial sebaceous neoplasm. Careful follow-up is required to help elucidate the biology of this tumor in an effort to determine the role of adjuvant therapy.

Pasireotide (SOM230): a novel pituitary-targeted medical therapy for the treatment of patients with Cushing's disease.

Cushing's disease (CD) is a rare and debilitating condition resulting from extended exposure to excessive glucocorticoids caused by an adrenocorticotropic hormone-secreting pituitary adenoma. First-line treatment for most patients with CD is trans-sphenoidal adenomectomy. Postsurgical remission remains problematic; however, due to the difficulty of removing the tumor. Until recently, there were no approved medical treatments for Cushing's syndrome, but recent data on pasireotide (SOM230; a novel somatostatin analog) demonstrate restored hormone levels and improvements in quality of life, with a safety profile similar to that of other somatostatin analogs, except for incidence of hyperglycemia. Pasireotide represents an exciting, novel, pituitary-targeted medical therapy for patients with CD who are not surgical candidates, or for those who experience postsurgical recurrence.

Recent advances in pituitary tumor management.

PURPOSE OF REVIEW: Advances in the neurosurgical management of pituitary tumors have included the refinement of surgical access and significant progress in navigation technology to help further reduce morbidity and improve outcome. Similarly, stereotactic radiosurgery has evolved to become an integral part in pituitary tumors not amenable to medical or surgical treatment. RECENT FINDINGS: The evolution of minimally invasive surgery has evolved toward endoscopic versus microscopic trans-sphenoidal approaches for pituitary tumors. Debate exists regarding each approach, with advocates for both championing their cause. Stereotactic and fractional radiosurgery have been shown to be a safe and effective means of controlling tumor growth and ensuring hormonal stabilization, with longer-term data available for GammaKnife compared with CyberKnife. SUMMARY: The advances in trans-sphenoidal surgical approaches, navigation technological improvements and the current results of stereotactic radiosurgery are discussed.

Intraoperative computed tomography registration and electromagnetic neuronavigation for transsphenoidal pituitary surgery: accuracy and time effectiveness.

OBJECT: The authors assessed the feasibility, anatomical accuracy, and cost effectiveness of frameless electromagnetic (EM) neuronavigation in conjunction with portable intraoperative CT (iCT) registration for transsphenoidal adenomectomy (TSA). METHODS: A prospective database was established for data obtained in 208 consecutive patients who underwent TSA in which the iCT/EM navigation technique was used. Data were compared with those acquired in a retrospective cohort of 65 consecutive patients in whom fluoroscope-assisted TSA had been performed by the same surgeon. All patients in both groups underwent transnasal removal of pituitary adenomas or neuroepithelial cysts, using identical surgical techniques with an operating microscope. In the iCT/EM technique-treated cases, a portable iCT scan was obtained immediately prior to surgery for registration to the EM navigation system, which did not require rigid head fixation. Preexisting (nonnavigation protocol) MR imaging studies were fused with the iCT scans to enable 3D navigation based on MR imaging data. The accuracy of the navigation system was determined in the first 50 iCT/EM cases by visual concordance of the navigation probe location to 5 preselected bony landmarks. For all patients in both cohorts, total operating room time, incision-to-closure time, and relative costs of imaging and surgical procedures were determined from hospital records. RESULTS: In every case, iCT registration was successful and preoperative MR images were fused to iCT scans without affecting navigation accuracy. There was 100% concordance between probe tip location and predetermined bony loci in the first 50 cases involving the iCT/EM technique. Total operating room time was significantly less in the iCT/EM cases (mean 108.9 ± 24.3 minutes [208 patients]) compared with the fluoroscopy group (mean 121.1 ± 30.7 minutes [65 patients]; p < 0.001). Similarly, incision-to-closure time was significantly less for the iCT/EM cases (mean 61.3 ± 18.2 minutes) than for the fluoroscopy cases (mean 71.75 ± 19.0 minutes; p < 0.001). Relative overall costs for iCT/EM technique and intraoperative C-arm fluoroscopy were comparable; increased costs for navigation equipment were offset by savings in operating room costs for shorter procedures. CONCLUSIONS: The use of iCT/MR imaging-guided neuronavigation for transsphenoidal surgery is a time-effective, cost-efficient, safe, and technically beneficial technique.