Earlier post-operative hypocortisolemia may predict durable remission from Cushing's disease

CONTEXT

Achievement of hypocortisolemia following transsphenoidal surgery (TSS) for Cushing's disease (CD) is associated with successful adenoma resection. However, up to one-third of these patients recur.

OBJECTIVE

We assessed whether delay in reaching post-operative cortisol nadir may delineate patients at risk of recurrence for CD following TSS.

METHODS

A retrospective review of 257 patients who received 291 TSS procedures for CD at NIH, between 2003 and 2016. Early biochemical remission (serum cortisol nadir <5 μg/dL) was confirmed with endocrinological and clinical follow-up. Recurrence was detected by laboratory testing, clinical stigmata or medication dependence during a median follow-up of 11 months.

RESULTS

Of the 268 unique admissions, remission was recorded in 241 instances. Recurrence was observed in 9% of these cases with cortisol nadir ≤5 μg/dL and 6% of cases with cortisol nadir ≤2 μg/dL. The timing of hypocortisolemia was critical in detecting late recurrences. Morning POD-1 cortisol <3.3 μg/dL was 100% sensitive in predicting durable remission and morning POD-3 cortisol ≥18.5 μg/dL was 98.6% specific in predicting remote recurrence. AUROC analysis revealed that hypocortisolemia ≤5 µg/dL before 15 h (post-operative) had 95% sensitivity and an NPV of 0.98 for durable remission. Serum cortisol level ≤2 µg/dL, when achieved before 21 h, improved sensitivity to 100%.

CONCLUSIONS

In our cohort, early, profound hypocortisolemia could be used as a clinical prediction tool for durable remission. Achievement of hypocortisolemia ≤2 µg/dL before 21 post-operative hours appeared to accurately predict durable remission in the intermediate term.

Surgical Management of Carney Complex-Associated Pituitary Pathology

BACKGROUND

Carney complex (CNC) is a familial neoplasia syndrome that is associated with pituitary-associated hypersecretion of growth hormone (GH) (acromegaly). The underlying cause of pituitary GH hypersecretion and its management have been incompletely defined.

OBJECTIVE

To provide biological insight into CNC-associated pituitary pathology and improve management, we analyzed findings in CNC patients who underwent transsphenoidal surgery.

METHODS

Consecutive CNC patients at the National Institutes of Health with acromegaly and imaging evidence of a pituitary adenoma(s) who underwent transsphenoidal resection of tumor(s) were included. Prospectively acquired magnetic resonance imaging and biochemical, surgical, and histological data were analyzed.

RESULTS

Seven acromegalic CNC patients (2 male, 5 female) were included. The mean age at surgery was 29.7 years (range, 18-44 years). The mean follow-up was 4.7 years (range, 0.2-129 months). Magnetic resonance imaging revealed a single pituitary adenoma in 4 patients and multiple pituitary adenomas in 3 patients. Whereas patients with single discrete pituitary adenomas underwent selective adenomectomy, patients with multiple adenomas underwent selective adenomectomy of multiple tumors, as well as partial or total hypophysectomy. All adenomas were either GH and prolactin positive or exclusively prolactin positive. Pituitary tissue surrounding the adenomas in patients with multiple adenomas revealed hyperplastic GH- and prolactin-positive tissue.

CONCLUSION

CNC-associated acromegaly results from variable pituitary pathology, including a single GH-secreting adenoma or multiple GH-secreting adenomas and/or GH hypersecretion of the pituitary gland surrounding multiple adenomas. Although selective adenomectomy is the preferred treatment for cases of GH-secreting adenomas, multiple adenomas with associated pituitary gland GH hypersecretion may require partial or complete hypophysectomy to achieve biochemical remission.

Imaging of Convective Drug Delivery in the Nervous System

Convection-enhanced delivery permits the direct homogeneous delivery of small- and large-molecular-weight putative therapeutics to the nervous system in a manner that bypasses the blood-nervous system barrier. The development of co-infused surrogate imaging tracers (for computed tomography and MRI) allows for the real-time, noninvasive monitoring of infusate distribution during convective delivery. Real-time image monitoring of convective distribution of therapeutic agents insures that targeted structures/nervous system regions are adequately perfused, enhances safety, informs efficacy (or lack thereof) of putative agents, and provides critical information regarding the properties of convection-enhanced delivery in normal and various pathologic tissue states.

Normalized Early Postoperative Cortisol and ACTH Values Predict Nonremission After Surgery for Cushing Disease

CONTEXT

Perioperative increases in adrenocorticotropic hormone (ACTH) and cortisol mimic results of corticotropin-releasing hormone (CRH) stimulation testing. This phenomenon may help identify patients with residual adenoma after transsphenoidal surgery (TSS) for Cushing disease (CD).

OBJECTIVE

To predict nonremission after TSS for CD.

DESIGN

Retrospective case-control study of patients treated at a single center from December 2003 until July 2016. Early and medium-term remission were assessed at 10 days and 11 months.

PATIENTS AND SETTING

Two hundred and ninety-one consecutive TSS cases from 257 patients with biochemical evidence of CD seen at a clinical center.

INTERVENTIONS

Normalized early postoperative values (NEPVs) for cortisol and ACTH were calculated as immediate postoperative cortisol or ACTH levels minus preoperative post-CRH-stimulation test levels.

MAIN OUTCOME MEASURES

Prediction of early nonremission was evaluated using logistic regression. Prediction of medium-term remission was assessed using Cox regression. Predictive ability was quantified by area under the receiver operating characteristic curve (AUROC).

RESULTS

NEPVs for cortisol and ACTH predicted early nonremission [adjusted odds ratio (OR): 1.1; 95% confidence interval (CI): 1.0, 1.1; P = 0.016 and adjusted OR: 1.0; 95% CI: 1.0, 1.0; P = 0.048, respectively]. AUROC for NEPV of cortisol was 0.78 (95% CI: 0.61, 0.95); for NEPV of ACTH, it was 0.80 (95% CI: 0.61, 0.98). NEPVs for cortisol and ACTH predicted medium-term nonremission [hazard ratio (HR): 1.1; 95% CI: 1.0, 1.1; P = 0.023 and HR: 1.0; 95% CI: 1.0, 1.0; P = 0.025, respectively].

CONCLUSIONS

NEPVs for cortisol and ACTH predicted nonremission after TSS for CD.

Personalized Medicine for Nervous System Manifestations of von Hippel-Lindau Disease

von Hippel–Lindau disease (VHL) is a familial neoplasia syndrome associated with multisystem tumor development. Depending on tumor type and location, current treatments for VHL-associated tumors can include a combination of chemotherapy, radiation therapy, and/or surgery. Central nervous system (CNS) manifestations of VHL include craniospinal hemangioblastomas and endolymphatic sac tumors (ELSTs). While the first-line treatment for both types of VHL-associated CNS tumors is surgery, the indications for treatment are patient specific and different for each tumor type. Although early sign/symptom formation is the primary indication for resection of craniospinal hemangioblastomas, radiographic discovery (asymptomatic and symptomatic) of ELSTs can be an indication for resection of ELSTs in VHL patients. Recently, research has revealed that specific VHL germline mutations may permit targeted medical treatments of not only CNS manifestations of VHL-associated tumors but also visceral tumors. Specifically, missense mutations can result in the translation of functional VHL protein (pVHL) that is rapidly degraded resulting in functional loss of the pVHL, and inhibitors of pVHL degradation may slow protein degradation and restore pVHL function. Emerging research will investigate the safety and practicality of using potential targeted therapies.

Cushing's disease: pathobiology, diagnosis, and management

Cushing's disease (CD) is the result of excess secretion of adrenocorticotropic hormone (ACTH) by a benign monoclonal pituitary adenoma. The excessive secretion of ACTH stimulates secretion of cortisol by the adrenal glands, resulting in supraphysiological levels of circulating cortisol. The pathophysiological levels of cortisol are associated with hypertension, diabetes, obesity, and early death. Successful resection of the CD-associated ACTH-secreting pituitary adenoma is the treatment of choice and results in immediate biochemical remission with preservation of pituitary function. Accurate and early identification of CD is critical for effective surgical management and optimal prognosis. The authors review the current pathophysiological principles, diagnostic methods, and management of CD.

The science and questions surrounding chronic traumatic encephalopathy

Recently, the pathobiology, causes, associated factors, incidence and prevalence, and natural history of chronic traumatic encephalopathy (CTE) have been debated. Data from retrospective case series and high-profile media reports have fueled public fear and affected the medical community's understanding of the role of sports-related traumatic brain injury (TBI) in the development of CTE. There are a number of limitations posed by the current evidence that can lead to confusion within the public and scientific community. In this paper, the authors address common questions surrounding the science of CTE and propose future research directions.

Activation of hypoxia signaling induces phenotypic transformation of glioma cells: implications for bevacizumab antiangiogenic therapy

Glioblastoma (GBM) is the most common and deadly primary brain tumor in adults. Bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor (VEGF), can attenuate tumor-associated edema and improve patient symptoms but based on magnetic resonance imaging, is associated with non-enhancing tumor progression and possibly gliosarcoma differentiation. To gain insight into these findings, we investigated the role of hypoxia and epithelial-mesenchymal transition (EMT)-associated proteins in GBM. Tumor markers of hypoxia and EMT were upregulated in bevacizumab-treated tumors from GBM patients compared to untreated counterparts. Exposure of glioma cells to 1% oxygen tension increased cell proliferation, expression of EMT-associated proteins and enhanced cell migration in vitro. These phenotypic changes were significantly attenuated by pharmacologic knockdown of hypoxia-inducible Factor 1α (HIF1α) or HIF2α, indicating that HIFs represent a therapeutic target for mesenchymal GBM cells. These findings provide insights into potential development of novel therapeutic targeting of angiogenesis-specific pathways in GBM.

Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery

OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing's disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra-high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm³ and 0.15 × 0.15 × 0.30 mm³, respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p < 0.01) in the SNR were inversely proportional to the distance from the ESC tip to the anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult pituitary adenomas and identify microscopic invasion of the dura or cavernous sinus.

Biological and clinical impact of hemangioblastoma-associated peritumoral cysts in von Hippel-Lindau disease

OBJECTIVE

Peritumoral cysts are frequently associated with CNS hemangioblastomas and often underlie neurological morbidity and mortality. To determine their natural history and clinical impact, the authors prospectively analyzed hemangioblastoma-associated peritumoral cysts in patients with von Hippel-Lindau (VHL) disease.

METHODS

Patients with VHL disease who had 2 or more years of follow-up and who were enrolled in a prospective study at the National Institutes of Health were included. Serial prospectively acquired laboratory, genetic, imaging, and clinical data were analyzed.

RESULTS

One hundred thirty-two patients (of 225 in the VHL study with at least 2 years of follow-up) had peritumoral cysts that were followed for more than 2 years (total of 292 CNS peritumoral cysts). The mean age at study entrance was 37.4 ± 13.1 years ([mean ± SD], median 37.9, range 12.3-65.1 years). The mean follow-up was 7.0 ± 1.7 years (median 7.3, range 2.1-9.0 years). Over the study period, 121 of the 292 peritumoral cysts (41.4%) became symptomatic. Development of new cysts was associated with a larger number cysts at study enrollment (p = 0.002) and younger age (p < 0.0001). Cyst growth rate was associated with anatomical location (cerebellum cysts grew faster than spine and brainstem cysts; p = 0.0002 and p = 0.0008), younger age (< 35 years of age; p = 0.0006), and development of new neurological symptoms (p < 0.0001). Cyst size at symptom production depended on anatomical location (p < 0.0001; largest to smallest were found, successively, in the cerebellum, spinal cord, and brainstem). The most common location for peritumoral cysts was the cerebellum (184 cysts [63%]; p < 0.0001).

CONCLUSIONS

Peritumoral cysts frequently underlie symptom formation that requires surgical intervention in patients with VHL disease. Development of new cysts was associated with a larger number of cysts at study enrollment and younger age. Total peritumoral cyst burden was associated with germline partial deletion of the VHL gene.

Real-time magnetic resonance imaging-guided frameless stereotactic brain biopsy: technical note

OBJECTIVE

The object of this study was to assess the feasibility, accuracy, and safety of real-time MRI-compatible frameless stereotactic brain biopsy.

METHODS

Clinical, imaging, and histological data in consecutive patients who underwent stereotactic brain biopsy using a frameless real-time MRI system were analyzed.

RESULTS

Five consecutive patients (4 males, 1 female) were included in this study. The mean age at biopsy was 45.8 years (range 29-60 years). Real-time MRI permitted concurrent display of the biopsy cannula trajectory and tip during placement at the target. The mean target depth of biopsied lesions was 71.3 mm (range 60.4-80.4 mm). Targeting accuracy analysis revealed a mean radial error of 1.3 ± 1.1 mm (mean ± standard deviation), mean depth error of 0.7 ± 0.3 mm, and a mean absolute tip error of 1.5 ± 1.1 mm. There was no correlation between target depth and absolute tip error (Pearson product-moment correlation coefficient, r = 0.22). All biopsy cannulae were placed at the target with a single penetration and resulted in a diagnostic specimen in all cases. Histopathological evaluation of biopsy samples revealed dysembryoplastic neuroepithelial tumor (1 case), breast carcinoma (1 case), and glioblastoma multiforme (3 cases).

CONCLUSIONS

The ability to place a biopsy cannula under real-time imaging guidance permits on-the-fly alterations in the cannula trajectory and/or tip placement. Real-time imaging during MRI-guided brain biopsy provides precise safe targeting of brain lesions.

Epidermal growth factor receptor as a novel molecular target for aggressive papillary tumors in the middle ear and temporal bone

Adenomatous tumors in the middle ear and temporal bone are rare but highly morbid because they are difficult to detect prior to the development of audiovestibular dysfunction. Complete resection is often disfiguring and difficult because of location and the late stage at diagnosis, so identification of molecular targets and effective therapies is needed. Here, we describe a new mouse model of aggressive papillary ear tumor that was serendipitously discovered during the generation of a mouse model for mutant EGFR-driven lung cancer. Although these mice did not develop lung tumors, 43% developed head tilt and circling behavior. Magnetic resonance imaging (MRI) scans showed bilateral ear tumors located in the tympanic cavity. These tumors expressed mutant EGFR as well as active downstream targets such as Akt, mTOR and ERK1/2. EGFR-directed therapies were highly effective in eradicating the tumors and correcting the vestibular defects, suggesting these tumors are addicted to EGFR. EGFR activation was also observed in human ear neoplasms, which provides clinical relevance for this mouse model and rationale to test EGFR-targeted therapies in these rare neoplasms.

Protein Phosphatase 2A Inhibition with LB100 Enhances Radiation-Induced Mitotic Catastrophe and Tumor Growth Delay in Glioblastoma

Protein phosphatase 2A (PP2A) is a tumor suppressor whose function is lost in many cancers. An emerging, though counterintuitive, therapeutic approach is inhibition of PP2A to drive damaged cells through the cell cycle, sensitizing them to radiotherapy. We investigated the effects of PP2A inhibition on U251 glioblastoma cells following radiation treatment in vitro and in a xenograft mouse model in vivo. Radiotherapy alone augmented PP2A activity, though this was significantly attenuated with combination LB100 treatment. LB100 treatment yielded a radiation dose enhancement factor of 1.45 and increased the rate of postradiation mitotic catastrophe at 72 and 96 hours. Glioblastoma cells treated with combination LB100 and radiotherapy maintained increased γ-H2AX expression at 24 hours, diminishing cellular repair of radiation-induced DNA double-strand breaks. Combination therapy significantly enhanced tumor growth delay and mouse survival and decreased p53 expression 3.68-fold, compared with radiotherapy alone. LB100 treatment effectively inhibited PP2A activity and enhanced U251 glioblastoma radiosensitivity in vitro and in vivo. Combination treatment with LB100 and radiation significantly delayed tumor growth, prolonging survival. The mechanism of radiosensitization appears to be related to increased mitotic catastrophe, decreased capacity for repair of DNA double-strand breaks, and diminished p53 DNA-damage response pathway activity.

Dr. Arvid Lindau and discovery of von Hippel-Lindau disease

Arvid Lindau, MD, PhD, consolidated the disparate array of benign and malignant visceral and nervous system lesions into the neoplastic syndrome known as von Hippel-Lindau (VHL) disease. Based on this pioneering work, Dr. Lindau was awarded both a Rockefeller fellowship to work in Dr. Harvey Cushing's laboratory in Boston, Massachusetts, and the Lennmalm Prize. While working in Dr. Cushing's laboratory, Dr. Lindau continued his study of CNS hemangioblastomas. His work with Dr. Cushing led to their lifelong friendship and scientific collaboration. In this paper the authors describe Arvid Lindau's pioneering work in nervous system tumor pathology, his relationship to Dr. Cushing, and his role in advancing neurological surgery and research in Europe.

Convection-enhanced delivery to the central nervous system

Convection-enhanced delivery (CED) is a bulk flow–driven process. Its properties permit direct, homogeneous, targeted perfusion of CNS regions with putative therapeutics while bypassing the blood-brain barrier. Development of surrogate imaging tracers that are co-infused during drug delivery now permit accurate, noninvasive real-time tracking of convective infusate flow in nervous system tissues. The potential advantages of CED in the CNS over other currently available drug delivery techniques, including systemic delivery, intrathecal and/or intraventricular distribution, and polymer implantation, have led to its application in research studies and clinical trials. The authors review the biophysical principles of convective flow and the technology, properties, and clinical applications of convective delivery in the CNS.