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Russell R Lonser

Publications and source records attributed to Russell R Lonser.

41 records · Page 3Linked to original sources
PubMed2003

Surgical management of lumbosacral nerve root hemangioblastomas in von Hippel-Lindau syndrome.

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.

Adult↗
PubMed2002

Epileptiform activity extinguished by amygdala infusion of the neurotoxin ibotenate in a rat model of temporal lobe epilepsy.

OBJECT: The long-term antiseizure effects of local convection-enhanced infusion of the excitotoxin ibotenate were examined in a rat model of temporal lobe epilepsy. METHODS: A single injection of kainate, an epileptogenic excitatory amino acid, into the left amygdala elicited chronic spontaneous recurrent seizure activity for at least 36 days after the injection. Two weeks after the injection, infusion of ibotenate, a nonepileptogenic excitatory amino acid that is an axon-sparing neuronal cell toxin, into the left amygdala and piriform lobe induced immediate and permanent extinction of electrical and behavioral seizure activity. CONCLUSIONS: Lesioning of an epileptic focus by convective distribution of ibotenate can produce an enduring suppression of seizure activity, indicating a chemical neurosurgical approach for epilepsy therapy.

Amygdala↗
PubMed2002

Successful and safe perfusion of the primate brainstem: in vivo magnetic resonance imaging of macromolecular distribution during infusion.

OBJECT: Intrinsic disease processes of the brainstem (gliomas, neurodegenerative disease, and others) have remained difficult or impossible to treat effectively because of limited drug penetration across the blood-brainstem barrier with conventional delivery methods. The authors used convection-enhanced delivery (CED) of a macromolecular tracer visible on magnetic resonance (MR) imaging to examine the utility of CED for safe perfusion of the brainstem. METHODS: Three primates (Macaca mulatta) underwent CED of various volumes of infusion ([Vis]; 85, 110, and 120 microl) of Gd-bound albumin (72 kD) in the pontine region of the brainstem during serial MR imaging. Infusate volume of distribution (Vd), homogeneity, and anatomical distribution were visualized and quantified using MR imaging. Neurological function was observed and recorded up to 35 days postinfusion. Histological analysis was performed in all animals. Large regions of the pons and midbrain were successfully and safely perfused with the macromolecular protein. The Vd was linearly proportional to the Vi (R2 = 0.94), with a Vd/Vi ratio of 8.7 +/- 1.2 (mean +/- standard deviation). Furthermore, the concentration across the perfused region was homogeneous. The Vd increased slightly at 24 hours after completion of the infusion, and remained larger until the intensity of infusion faded (by Day 7). No animal exhibited a neurological deficit after infusion. Histological analysis revealed normal tissue architecture and minimal gliosis that was limited to the region immediately surrounding the cannula track. CONCLUSIONS: First, CED can be used to perfuse the brainstem safely and effectively with macromolecules. Second, a large-molecular-weight imaging tracer can be used successfully to deliver, monitor in vivo, and control the distribution of small- and large-molecular-weight putative therapeutic agents for treatment of intrinsic brainstem processes.

Albumins↗
PubMed2002

Induction of glioblastoma multiforme in nonhuman primates after therapeutic doses of fractionated whole-brain radiation therapy.

OBJECT: To determine the acute and long-term effects of a therapeutic dose of brain radiation in a primate model, the authors studied the clinical, laboratory, neuroimaging, molecular, and histological outcomes in rhesus monkeys that had received fractionated whole-brain radiation therapy (WBRT). METHODS: Twelve 3-year-old male primates (Macaca mulatta) underwent fractionated WBRT (350 cGy for 5 days/week for 2 weeks, total dose 3500 cGy). Animals were followed clinically and with laboratory studies and serial magnetic resonance (MR) imaging. They were killed when they developed medical problems or neurological symptoms, lesions appeared on MR imaging, or at study completion. Gross, histological, and molecular analyses were then performed. Nine (82%) of 11 animals that underwent long-term follow up (> 2.5 years) developed neurological symptoms and/or enhancing lesions on MR imaging, which were defined as glioblastoma multiforme (GBM), 2.9 to 8.3 years after radiation therapy. The GBMs were categorized as either unifocal (three) or multifocal (six), and were located in the supratentorial (six), infratentorial (two), or both (one) cranial regions. Histological examination revealed distant, noncontiguous tumor invasion within the white matter of all nine animals harboring GBMs. Novel interspecies comparative genomic hybridization (three animals) uniformly showed deletions in the GBMs that corresponded to chromosome 9 in humans. CONCLUSIONS: The high rate of GBM formation (82%) following a therapeutic dose of WBRT in nonhuman primates indicates that radioinduction of these neoplasms as a late complication of this therapy may occur more frequently than is currently recognized in human patients. The development of these tumors while monitoring the monkeys' conditions with clinical and serial MR imaging studies, and access to the tumor and the entire brain for histological and molecular analyses offers an opportunity to gather unique insights into the nature and development of GBMs.

Animals↗