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Jay Jagannathan, John A. Butman, Russell R. Lonser, Alexander O. Vortmeyer, Christopher K. Zalewski, Carmen Brewer, Edward H. Oldfield, and H. Jeffrey Kim

✓ Endolymphatic sac tumors (ELSTs) are locally invasive neoplasms that arise in the posterior petrous bone and are associated with von Hippel–Lindau (VHL) disease. These tumors cause symptoms even when microscopic in size (below the threshold for detectability on imaging studies) and can lead to symptoms such as hearing loss, tinnitus, vertigo, and facial nerve dysfunction. While the mechanisms of audiovestibular dysfunction in patients harboring ELSTs are incompletely understood, they have critical implications for management. The authors present the case of a 33-year-old man with VHL disease and a 10-year history of progressive tinnitus, vertigo, and left-sided hearing loss. Serial T1-weighted magnetic resonance (MR) imaging and computed tomography scans revealed no evidence of tumor, but fluid attenuated inversion recovery (FLAIR) MR imaging sequences obtained after hearing loss demonstrated evidence of left intralabyrinthine hemorrhage. On the basis of progressive disabling audiovestibular dysfunction (tinnitus and vertigo), FLAIR imaging findings, and VHL disease status, the patient underwent surgical exploration of the posterior petrous region, and a small (2-mm) ELST was identified and completely resected. Postoperatively, the patient had improvement of the tinnitus and vertigo. Intralabyrinthine hemorrhage may be an early and the only neuroimaging sign of an ELST in patients with VHL disease and audiovestibular dysfunction. These findings support tumor-associated hemorrhage as a mechanism underlying the audiovestibular dysfunction associated with ELSTs.

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Nicholas J. Szerlip, Stuart Walbridge, Linda Yang, Paul F. Morrison, Jeffrey W. Degen, S. Taylor Jarrell, Joshua Kouri, P. Benjamin Kerr, Robert Kotin, Edward H. Oldfield, and Russell R. Lonser

Object

Despite recent evidence showing that convection-enhanced delivery (CED) of viruses and virus-sized particles to the central nervous system (CNS) is possible, little is known about the factors influencing distribution of these vectors with convection. To better define the delivery of viruses and virus-sized particles in the CNS, and to determine optimal parameters for infusion, the authors coinfused adeno-associated virus ([AAV], 24-nm diameter) and/or feru-moxtran-10 (24 nm) by using CED during real-time magnetic resonance (MR) imaging.

Methods

Sixteen rats underwent intrastriatal convective coinfusion with 4 μl of 35S-AAV capsids (0.5–1.0 × 1014 viral particles/ml) and increasing concentrations (0.1, 0.5, 1, and 5 mg/ml) of a similar sized iron oxide MR imaging agent (ferumoxtran-10). Five nonhuman primates underwent either convective coinfusion of 35S-AAV capsids and 1 mg/ml ferumoxtran-10 (striatum, one animal) or infusion of 1 mg/ml ferumoxtran-10 alone (striatum in two animals; frontal white matter in two). Clinical effects, MR imaging studies, quantitative autoradiography, and histological data were analyzed.

Results

Real-time, T2-weighted MR imaging of ferumoxtran-10 during infusion revealed a clearly defined hypo-intense region of perfusion. Quantitative autoradiography confirmed that MR imaging of ferumoxtran-10 at a concentration of 1 mg/ml accurately tracked viral capsid distribution in the rat and primate brain (the mean difference in volume of distribution [Vd] was 7 and 15% in rats and primates, respectively). The Vd increased linearly with increasing volume of infusion (Vi) (R2 = 0.98). The mean Vd/Vi ratio was 4.1 ± 0.2 (mean ± standard error of the mean) in gray and 2.3 ± 0.1 in white matter (p < 0.01). The distribution of infusate was homogeneous. Postinfusion MR imaging revealed leakback along the cannula track at infusion rates greater than 1.5 μl/minute in primate gray and white matter. No animal had clinical or histological evidence of toxicity.

Conclusions

The CED method can be used to deliver AAV capsids and similar sized particles to the CNS safely and effectively over clinically relevant volumes. Moreover, real-time MR imaging of ferumoxtran-10 during infusion reveals that AAV capsids and similar sized particles have different convective delivery properties than smaller proteins and other compounds.

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Jay Jagannathan, Russell R. Lonser, Rene Smith, Hetty L. DeVroom, and Edward H. Oldfield

Object

Despite the frequency of cerebellar hemangioblastomas in von Hippel–Lindau (VHL) disease, their optimum contemporary management has not been defined, and is made complex because of the multiple, progressive, and protean nature of the tumors found in patients with this disorder. To examine modern management and outcomes of cerebellar hemangioblastomas in VHL disease, the authors reviewed findings in patients with this disease who underwent resection of cerebellar hemangioblastomas.

Methods

Consecutive patients with VHL disease who underwent surgery for cerebellar hemangioblastoma(s) at the National Institutes of Health were included. Eighty consecutive patients (44 female and 36 male patients) underwent 126 operations for removal of 164 cerebellar hemangioblastomas (age at surgery 37.8 ± 10.3 years, follow-up duration 96.0 ± 60.3 months). Serial clinical examinations, imaging studies, and operative records were analyzed.

Results

Symptoms and signs included headache (94 operations; 75%), ataxia (55%), dysmetria (29%), and hydrocephalus (28%). Although the primary objective of surgery was resection of the hemangioblastoma considered responsible for symptoms (136 of the hemangioblastomas [83%]), 28 additional hemangioblastomas (17%) were removed during the same surgeries. Tumors associated with symptoms were larger (diameter 1.8 ± 1.9 cm; volume 2.8 ± 3.4 cm3; p < 0.05) and more likely to be associated with peritumoral edema or peritumoral cysts (100% associated with edema and/or cyst; p < 0.05) than asymptomatic tumors (diameter 1.1 ± 0.9 cm; volume 0.7 ± 0.4 cm3; 18%). More tumors were located in the posterior (74%) compared with the anterior (26%) half of the cerebellum (p < 0.05). Three months after resection, symptom improvement/stabilization had occurred following 124 of the operations (98%). Preoperative hydrocephalus resolved after tumor removal in 33 cases (94%) and did not require cerebrospinal fluid diversion. Long-term imaging follow-up (61.5 ± 15.0 months) revealed no recurrences.

Conclusions

Symptoms and signs caused by cerebellar hemangioblastomas in VHL disease are associated with edema and peritumoral cyst formation/propagation and are treated safely and effectively with resection. Cerebrospinal fluid diversion is rarely necessary after complete tumor removal in patients with preoperative hydrocephalus. Cerebellar hemangioblastomas are preferentially distributed in the posterior half of the cerebellum, as they are in the brainstem and spinal cord. Tumor recurrence is avoided by meticulous extracapsular resection.

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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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Martin Baggenstos, Emily Chew, John A. Butman, Edward H. Oldfield, and Russell R. Lonser

Hemangioblastomas are frequently associated with peritumoral edema caused by extravasation of plasma ultrafiltrate through permeable neoplastic vessels. The authors report the clinical and imaging findings in a 62-year-old man with von Hippel–Lindau disease who presented with rapid (within 24 hours) loss of color vision and nearcomplete loss of left eye vision (acuity too poor to test). Serial MR imaging demonstrated a stable vascular tumor in the medioinferior aspect of the left optic nerve, associated with progressive edema extending from the nerve through to the bilateral optic radiations. Complete resection of the lesion was performed via an extended transsphenoidal approach, and histological examination confirmed the lesion was a hemangioblastoma. Postoperatively, the patient recovered color vision and had improvement in visual acuity (20/320). Serial imaging in this unique case captured the progressive extravasation of peritumoral edema that tracked and defined the parallel white matter tracts of first- and second-order neurons of the optic system, causing vision loss. Tumor resection led to resolution of the edema and improvement in visual function.

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Jay Jagannathan, Stuart Walbridge, John A. Butman, Edward H. Oldfield, and Russell R. Lonser

Object

Convection-enhanced delivery (CED) is increasingly used to investigate new treatments for central nervous system disorders. Although the properties of CED are well established in normal gray and white matter central nervous system structures, the effects on drug distribution imposed by ependymal and pial surfaces are not precisely defined. To determine the effect of these anatomical boundaries on CED, the authors infused low MW and high MW tracers for MR imaging near ependymal (periventricular) and pial (pericisternal) surfaces.

Methods

Five primates underwent CED of Gd-diethylenetriamine pentaacetic acid (Gd-DTPA; MW 590 D) or Gd-bound albumin (Gd-albumin; MW 72,000 D) during serial real-time MR imaging (FLAIR and T1-weighted sequences). Periventricular (caudate) infusions were performed unilaterally in 1 animal (volume of infusion [Vi] 57 μl) and bilaterally in 1 animal with Gd-DTPA (Vi = 40 μl on each side), and bilaterally in 1 animal with Gd-albumin (Vi = 80 μl on each side). Pericisternal infusions were performed in 2 animals with Gd-DTPA (Vi = 190 μl) or with Gd-albumin (Vi = 185 μl) (1 animal each). Clinical effects, MR imaging, and histology were analyzed.

Results

Large regions of the brain and brainstem were perfused with both tracers. Intraparenchymal distribution was successfully tracked in real time by using T1-weighted MR imaging. During infusion, the volume of distribution (Vd) increased linearly (R2 = 0.98) with periventricular (mean Vd/Vi ratio ± standard deviation; 4.5 ± 0.5) and pericisternal (5.2 ± 0.3) Vi, but did so only until the leading edge of distribution reached the ependymal or pial surfaces, respectively. After the infusate reached either surface, the Vd/Vi decreased significantly (ependyma 2.9 ± 0.8, pia mater 3.6 ± 1.0; p < 0.05) and infusate entry into the ventricular or cisternal cerebrospinal fluid (CSF) was identified on FLAIR but not on T1-weighted MR images.

Conclusions

Ependymal and pial boundaries are permeable to small and large molecules delivered interstitially by convection. Once infusate reaches these surfaces, a portion enters the adjacent ventricular or cisternal CSF and the tissue Vd/Vi ratio decreases. Although T1-weighted MR imaging is best for tracking intraparenchymal infusate distribution, FLAIR MR imaging is the most sensitive and accurate for detecting entry of Gd-labeled imaging compounds into CSF during CED.

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Satoru Shimizu

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Steven M. Sorscher

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Debbie K. Song and Russell R. Lonser

Because of the multiplicity and saltatory growth pattern associated with central nervous system hemangioblastomas in von Hippel-Lindau (VHL) disease, resection of individual tumors is usually reserved until symptoms occur, to avoid unnecessary surgery over the lifetime of a patient. Brainstem hemangioblastomas in VHL typically cause lower cranial nerve dysfunction, long-tract signs, sensory impairment, and gait abnormalities. The authors report on a 16-year-old girl with VHL who presented with abnormal early satiety resulting in growth and developmental arrest associated with a growing obex hemangioblastoma. Tumor resection resulted in restoration of appetite, with rapid weight gain, growth in stature, and onset of menses. These findings indicate that caudal brainstem-mediated mechanisms have a profound effect on satiety. Moreover, brainstem hemangioblastomas may present with abnormalities in satiety and feeding that can be effectively reversed with resection.

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Russell R. Lonser, John A. Butman, Ruwan Kiringoda, Debbie Song, and Edward H. Oldfield

Object

Pituitary stalk hemangioblastomas are rare, and information on them is limited to a small number of case reports. To gain insight into the incidence, clinical effects, and management of pituitary stalk hemangioblastomas, the authors analyzed a series of patients with von Hippel–Lindau (VHL) disease.

Methods

Patients with VHL disease who were enrolled in a prospective National Institutes of Health natural history study were included. Clinical, imaging, and laboratory findings were analyzed.

Results

Two hundred fifty patients were included in the study (120 male and 130 female patients). In 8 patients (3%), 8 pituitary stalk hemangioblastomas were identified on MR imaging. This anatomical location was the most common supratentorial site for these lesions; 29% of all supratentorial hemangioblastomas were found there. The mean (± standard deviation) pituitary stalk hemangioblastoma volume was 0.5 ± 0.9 cm3 (range 0.08–2.8 cm3). Results of endocrine laboratory profiles were normal in all patients. All patients remained asymptomatic and none required treatment during the follow-up period (mean duration 41.4 ± 14.4 months).

Conclusions

The pituitary stalk is the most common site for the development of supratentorial hemangioblastomas in patients with VHL disease. Pituitary stalk hemangioblastomas often remain asymptomatic and do not require treatment. These findings indicate that pituitary stalk hemangioblastomas in patients with VHL disease may be managed with observation and that surgery for them can be reserved until associated signs or symptoms occur.