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Edward H. Oldfield and Alexander O. Vortmeyer

Object

The presence of a histological pseudocapsule around pituitary tumors was noted in the early 1900s. Since that time there has been no emphasis on the sequence of the stages of its development or on the relationship between these stages and the capacity to identify very small pituitary tumors at surgery in patients in whom preoperative imaging has been nondiagnostic. In addition, limited emphasis has been given to the pseudocapsule’s use for selective and complete resection of pituitary adenomas.

Methods

The development of the pseudocapsule was examined by performing histological analysis of portions of pituitary glands removed during 805 operations for Cushing disease.

Twenty-five adenomas, each measuring between 0.25 and 4 mm in maximum diameter, were detected in the excised specimens; 17 were adenocorticotropic hormone–positive adenomas and eight were incidental tumors (four prolactin-secreting and four nonsecreting lesions). In 16 tumors the size of the adenoma could be established. The distribution of tumor size in relation to the presence of a histological pseudocapsule indicates a transition from the absence of a reticulin capsule (tumor diameter ≤ 1 mm) through the initial compression of surrounding tissue (tumor diameter 1–2 mm) to the presence of a multilayered reticulin capsule observed when adenomas become larger (tumor diameter 2–3 mm).

Conclusions

The absence of a reticulin capsule in cases of very small tumors may contribute to limited localization of these lesions during surgical exploration of the pituitary gland. In this article the authors describe surgical techniques in which the histological pseudocapsule is used as a surgical capsule during pituitary surgery. In their experience, recognition of this surgical capsule and its use at surgery has contributed to the identification of microadenomas buried in the pituitary gland, aided the recognition of subtle invasion of the pituitary capsule and contiguous dura mater, and enhanced the consistency of complete tumor excision with small and large tumors.

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Gabriel C. Tender, Alexander O. Vortmeyer, and Edward H. Oldfield

✓ Intradural spinal arteriovenous fistulas (AVFs), a subtype of spinal arteriovenous malformation in which there is a direct communication between a spinal artery and a vein on the cord surface or in the subarachnoid space, are generally considered to be congenital lesions caused by maldevelopment of the embryonic vascular system. The authors present the cases of two patients with acquired AVFs of the terminal filum. In each patient an AVF between the distal segment of the anterior spinal artery and its accompanying vein on the terminal filum developed within 1 year of repeated lumbar myelography that had demonstrated no evidence of abnormal vascularity. In both patients spinal arteriography demonstrated the absence of medullary venous drainage in the thoracolumbar region, which, combined with the arterialized venous input from the AVF, permitted the development of venous congestion and myelopathy. The involved segment of the terminal filum was excised; in vitro microarteriography and the histopathological examination demonstrated a single, simple arteriovenous connection in both patients.

The findings in these cases indicate that intradural AVF can spontaneously arise in later life. The development of these lesions and/or their clinical manifestation may require not only the presence of the AVF, but also deficiency of medullary spinal venous drainage. The epidemiology and anatomy of intradural AVFs are compatible with an acquired origin in many cases.

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Russell R. Lonser, Alexander Ksendzovsky, Joshua J. Wind, Alexander O. Vortmeyer, and Edward H. Oldfield

Object

Dural invasion by adrenocorticotropic hormone (ACTH)-secreting adenomas is a significant risk factor for incomplete resection and recurrence in Cushing disease (CD). Since ACTH-producing adenomas are often the smallest of the various types of pituitary tumors at the time of resection, examining their invasion provides the best opportunity to identify the precise sites of early dural invasion by pituitary adenomas. To characterize the incidence and anatomical distribution of dural invasion by ACTH-secreting adenomas, the authors prospectively and systematically analyzed features of dural invasion in patients with CD.

Methods

The authors prospectively studied consecutive patients with CD undergoing the systematic removal of ACTH-secreting adenoma and histological analysis of the anterior sella dura as well as other sites of dural invasion that were evident at surgery. Clinical, imaging, histological, and operative findings were analyzed.

Results

Eighty-seven patients with CD (58 females and 29 males) were included in the study. Overall, dural invasion by an ACTH-positive adenoma was histologically confirmed in 30 patients (34%). Eighteen patients (60% of dural invasion cases, 21% of all patients) had evidence of cavernous sinus wall invasion (4 of these patients also had other contiguous sites of invasion), and 12 patients (40% of dural invasion cases) had invasion of the sella dura excluding the cavernous sinus wall. Eleven patients (13% all patients) had invasion of the routinely procured anterior sella dura specimen. Preoperative MR imaging revealed an adenoma in 64 patients (74%) but accurately predicted dural invasion in only 4 patients (22%) with cavernous sinus invasion and none of the patients with non–cavernous sinus invasion. Adenomas associated with dural invasion (mean ± SD, 10.9 ± 7.8 mm, range 2–37 mm) were significantly larger than those not associated with dural invasion (5.7 ± 2.1 mm, range 2.5–12 mm; p = 0.0006, Mann-Whitney test).

Conclusions

Dural invasion by ACTH-producing adenomas preferentially occurs laterally into the wall of the cavernous sinus. Preoperative MR imaging infrequently detects dural invasion, including cavernous sinus invasion. Invasion is directly associated with tumor size. To provide a biochemical cure and avoid recurrence after resection, identification and removal of invaded sella dura, including the medial cavernous sinus wall, are necessary.

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Brian J. Kelley, Michele H. Johnson, Alexander O. Vortmeyer, Brian G. Smith, and Khalid M. Abbed

The authors report a case in which multilevel thoracic pedicle subtraction osteotomy (PSO) was performed to correct post-laminectomy kyphotic deformity in a 9-year-old boy presenting with worsening lower-extremity neurological deficits. Five years prior to presentation, the patient underwent multilevel thoracolumbar laminectomies for resection of an atypical teratoid/rhabdoid tumor (AT/RT), a rare lesion that typically occurs intracranially and has a poor prognosis, making this particular presentation unusual and the patient's subsequent postoperative course remarkable. No fusion was undertaken at the time of resection, given the patient's age and presumptive poor prognosis. Over the next 5 years, the patient developed progressive thoracolumbar kyphotic deformity, with a Cobb angle greater than 110°, despite bracing, and bilateral lower-extremity weakness requiring ankle-foot orthotics for continued ambulation due to progressive foot drop. Worsening gait and the onset of respiratory issues prompted surgical intervention. Multilevel thoracic PSO and thoracolumbar fusion were performed, resulting in improved lower-extremity function and correction of the kyphotic deformity to approximately 65°. This report outlines an unusual AT/RT presentation and postoperative course and also discusses literature related to PSO within the context of pediatric kyphotic deformity. The authors' experience supports the use of multilevel PSO with fusion as a potential treatment option for significant pediatric thoracolumbar kyphotic deformity requiring surgical correction.

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Jeffrey W. Degen, Stuart Walbridge, Alexander O. Vortmeyer, Edward H. Oldfield, and Russell R. Lonser

Object. Convection-enhanced delivery (CED) can be used safely to perfuse regions of the central nervous system (CNS) with therapeutic agents in a manner that bypasses the blood—brain barrier (BBB). These features make CED a potentially ideal method for the distribution of potent chemotherapeutic agents with certain pharmacokinetic properties to tumors of the CNS. To determine the safety and efficacy of the CED of two chemotherapeutic agents (with properties ideal for this method of delivery) into the CNS, the authors perfused naive rats and those harboring 9L gliomas with carboplatin or gemcitabine.

Methods. Dose-escalation toxicity studies were performed by perfusing the striatum (10 µl, 24 rats) and brainstem (10 µl, 16 rats) of naive rats with carboplatin (0.1, 1, and 10 mg/ml) or gemcitabine (0.4, 4, and 40 mg/ml) via CED. Efficacy trials involved the intracranial implantation of 9L tumor cells in 20 Fischer 344 rats. The tumor and surrounding regions were perfused with 40 µl of saline (control group, four rats), 1 mg/ml of carboplatin (four rats), or 4 mg/ml of gemcitabine (four rats) 7 days after implantation. Eight rats harboring the 9L glioma were treated with the systemic administration of 60 mg/kg of carboplatin (four rats) or 150 mg/kg of gemcitabine (four rats) 7 days postimplantation. Clinical, gross, and histological analyses were used to determine toxicity and efficacy.

Toxicity occurred in rats that had received only the highest dose of the CED of carboplatin or gemcitabine. Among rats with 9L gliomas, all control and systemically treated animals died within 26 days of tumor implantation. Long-term survival (120 days) and eradication of the tumor occurred in both CED-treated groups (75% of rats in the carboplatin group and 50% of rats in the gemcitabine group). Furthermore, animals harboring the 9L glioma and treated with intratumoral CED of carboplatin or gemcitabine survived significantly longer than controls treated with intratumoral saline (p < 0.01) or systemic chemotherapy (p < 0.01).

Conclusions. The perfusion of sensitive regions of the rat brain can be accomplished without toxicity by using therapeutic concentrations of carboplatin or gemcitabine. In addition, CED of carboplatin or gemcitabine to tumors in this glioma model is safe and has potent antitumor effects. These findings indicate that similar treatment paradigms may be useful in the treatment of glial neoplasms in humans.

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Lance S. Governale, Alexander O. Vortmeyer, Zhengping Zhuang, and Edward H. Oldfield

✓ Meningioma has been included in the constellation of tumors associated with von Hippel—Lindau (VHL) disease in previously published reports. It is unclear whether these tumors are an uncommon component of VHL disease or are more readily detected in these patients because of the frequency with which they undergo central nervous system imaging as part of the routine management of VHL disease. The authors report the case of a patient with VHL disease in whom a progressively enlarging supratentorial mass developed and was diagnosed as a hemangioblastoma because of its appearance on serial magnetic resonance images. At surgery the tumor displayed the typical features of a meningioma and was given the histological diagnosis of fibrous meningioma. Single-stranded conformational polymorphism analysis of the tumor DNA revealed a loss of heterozygosity at the neurofibromatosis Type 2 gene locus, known to be associated with sporadically occurring meningiomas. Despite this finding, the VHL gene locus on the allele from the patient's unaffected parent was normal. Thus it is unlikely that the occurrence of this patient's fibrous meningioma was associated with underlying VHL disease. Given the high frequency of neuroimaging sessions in patients with VHL disease, some supratentorial lesions that have been given radiological diagnoses of hemangioblastomas may be incidental meningiomas.

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Russell R. Lonser, Martin Baggenstos, H. Jeffrey Kim, John A. Butman, and Alexander O. Vortmeyer

Object

Although endolymphatic sac tumors (ELSTs) frequently destroy the posterior petrous bone and cause hearing loss, the anatomical origin of these neoplasms is unknown. To determine the precise topographic origin of ELSTs, the authors analyzed the imaging, operative, and pathological findings in patients with von Hippel–Lindau disease (VHL) and ELSTs.

Methods

Consecutive VHL patients with small (≤ 1.5 cm) ELSTs who underwent resection at the National Institutes of Health were included. Clinical, imaging, operative, and pathological findings were analyzed.

Results

Ten consecutive VHL patients (6 male and 4 female) with 10 small ELSTs (≤ 1.5 cm; 9 left, 1 right) were included. Serial imaging captured the development of 6 ELSTs and revealed that they originated within the intraosseous (vestibular aqueduct) portion of the endolymphatic duct/sac system. Imaging just before surgery demonstrated that the epicenters of 9 ELSTs (1 ELST was not visible on preoperative imaging) were in the vestibular aqueduct. Inspection during surgery established that all 10 ELSTs were limited to the intraosseous endolymphatic duct/sac and the immediately surrounding region. Histological analysis confirmed tumor within the intraosseous portion (vestibular aqueduct) of the endolymphatic duct/sac in all 10 patients.

Conclusions

ELSTs originate from endolymphatic epithelium within the vestibular aqueduct. High-resolution imaging through the region of the vestibular aqueduct is essential for diagnosis. Surgical exploration of the endolymphatic duct and sac is required for complete resection.

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S. Taylor Jarrell, Alexander O. Vortmeyer, W. Marston Linehan, Edward H. Oldfield, and Russell R. Lonser

Object

Patients with hereditary cancer syndromes may be at increased risk for the development of tumor-to-tumor metastases. To gain insight into the biological nature of these lesions in the central nervous system (CNS), to determine their prevalence in a familial neoplasia syndrome, and to better define their management, the authors retrospectively examined a series of cases in which metastatic lesions developed within hemangioblastomas in patients with von Hippel–Lindau (VHL) disease.

Methods

The study included all cases of VHL disease in which patients underwent resection of a CNS hemangioblastoma that contained a metastasis or were found at autopsy to have a metastasis to a hemangioblastoma between January 2002 and December 2005 at the National Institute of Neurological Disorders and Stroke (NINDS). Clinical, histopathological, imaging, and surgical and/or autopsy findings were analyzed.

Metastasis to a CNS hemangioblastoma was found in six resected tumors (8% of all hemangioblastomas resected from patients with VHL disease at the NINDS during the study period) from six patients (five women, one man; mean age at surgery 42.5 years). The primary site of metastatic disease was the kidney in five patients (renal cell carcinoma) and the pancreas in one (a pancreatic neuroendocrine tumor). Only one patient had systemic metastases at the time of resection of the hemangioblastoma containing the metastasis. Neurologically, all patients had remained at baseline or were improved at last clinical follow-up examination (mean follow-up duration 16.5 months, range 3–40 months). In all cases, postoperative imaging revealed that the hemangioblastoma resection was complete, and there was no evidence of recurrence in any of the patients at the last follow up. Two patients (including one who was also in the surgical group) were found at autopsy to have CNS metastases exclusively to spinal hemangioblastomas.

Conclusions

Hemangioblastomas are an early and preferred site for metastasis in VHL disease. Emerging histopathological techniques may lead to recognition of an increasing number of cases of tumor-to-hemangioblastoma metastasis. Management of cases involving tumor-to-hemangioblastoma metastases in VHL disease should be based on the histological characteristics of the primary tumor, extent of the primary disease, and completeness of the resection.

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Russell R. Lonser, Scott D. Wait, John A. Butman, Alexander O. Vortmeyer, McClellan M. Walther, Lance S. Governale, and Edward H. Oldfield

Object

Hemangioblastomas in the lumbosacral region are rare, and the authors of prior reports have not defined the surgical management, histopathological features, or outcome in a group of patients after resection of these tumors. To identify features that will help guide the operative and clinical management of these lesions, the authors reviewed data obtained in a series of patients with von Hippel—Lindau syndrome who underwent resection of lumbosacral nerve root hemangioblastomas.

Methods

Six consecutive patients (three men and three women; mean age at surgery 39 years [range 31–48 years]) who underwent operations for resection of lumbosacral nerve root hemangioblastomas were included in this study. The mean follow-up period was 23 months (range 6–45 months). Data derived from examination, hospital charts, operative findings, histopathological analysis, and magnetic resonance imaging were used to analyze surgical management and clinical outcome. The resected tumors were located in the lumbar (five cases) or sacral (one case) regions; the mean tumor size was 2728 mm3 (range 80–15,022 mm3). Consistent with central nervous system (CNS) regional variation of space available to accommodate the neural compressive effect of the hemangioblastoma size, the mean tumor volume (2728 mm3) of these symptomatic lesions was much larger than that of symptomatic hemangioblastomas resected in the other regions of the CNS. Histopathological examination showed infiltration of the associated nerve root by the hemangioblastoma in each case. In five of the six patients complete resection was achieved, and in one patient intradural exploration of two hemangioblastomas was performed, but resection was not achieved because of motor root involvement. In all cases involving complete resections the patients experienced symptomatic improvement.

Conclusions

Lumbosacral nerve root hemangioblastomas can be safely removed in most patients with von Hippel—Lindau syndrome. Generally, hemangioblastomas of the lumbosacral nerve roots should be resected when they become symptomatic. Because these neoplasms appear to originate from the nerve root, it is necessary to sacrifice the nerve root from which the hemangioblastoma originates to achieve complete resection.

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Ryszard M. Pluta, Scott D. Wait, John A. Butman, Kathleen A. Leppig, Alexander O. Vortmeyer, Edward H. Oldfield, and Russell R. Lonser

Hemangioblastomas are histologically benign neoplasms that occur sporadically or as part of von Hippel–Lindau disease. Hemangioblastomas may occur anywhere along the neuraxis, but sacral hemangioblastomas are extremely rare. To identify features that will help guide the operative and clinical management of these lesions, the authors describe the management of a large von Hippel–Lindau disease–associated sacral hemangioblastoma and review the literature.

The authors present the case of a 38-year-old woman with von Hippel–Lindau disease and a 10-year history of progressive back pain, as well as left lower-extremity pain and numbness. Neurological examination revealed decreased sensation in the left S-1 and S-2 dermatomes. Magnetic resonance imaging demonstrated a large enhancing lesion in the sacral region, with associated erosion of the sacrum. The patient underwent arteriography and embolization of the tumor and then resection. The histopathological diagnosis was consistent with hemangioblastoma and showed intrafascicular tumor infiltration of the S-2 nerve root. At 1-year follow-up examination, pain had resolved and numbness improved.

Sacral nerve root hemangioblastomas may be safely removed in most patients, resulting in stabilization or improvement in symptomatology. Generally, hemangioblastomas of the sacral nerve roots should be removed when they cause symptoms. Because they originate from the nerve root, the nerve root from which the hemangioblastoma originates must be sacrificed to achieve complete resection.