Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where George Krol is active.

Publication


Featured researches published by George Krol.


International Journal of Radiation Oncology Biology Physics | 1989

Patterns of failure following treatment for glioblastoma multiforme and anaplastic astrocytoma

Kent Wallner; Joseph H. Galicich; George Krol; Ehud Arbit; Mark G. Malkin

Recurrence patterns of glioblastoma multiforme (25) and anaplastic astrocytoma (9) were studied using CT scans of 34 patients who received all or a portion of their surgical treatment at Memorial Sloan-Kettering Cancer Center from January 1983 through February 1987. Thirty-two patients presented with unifocal tumors and two with multifocal tumors. All patients received radiation therapy following initial surgery. Eighteen patients who underwent re-operation following CT evidence of recurrence had histologic verification of recurrent tumor; sixteen patients had radiographic evidence of recurrence only. Seventy-eight percent (25/32) of unifocal tumors recurred within 2.0 cm of the pre-surgical, initial tumor margin, defined as the enhancing edge of the tumor on CT scan. Fifty-six percent (18/32) of tumors recurred within 1.0 cm of the initial tumor margin. Tumors for which a gross total resection was accomplished tended to recur closer to the initial tumor margin than did subtotally resected tumors (p greater than 0.1). Extensive pre-operative edema was associated with a decreased distance between initial and recurrent tumor margins. Large tumors were generally not more likely to recur further from the initial tumor margin than were smaller tumors. No unifocal tumor recurred as a multifocal tumor. Only one tumor (initially near the midline) recurred in the contralateral hemisphere. The findings support the use of partial brain irradiation for post-operative treatment of glioblastoma multiforme and anaplastic astrocytomas, and may help to determine the most appropriate treatment volume for interstitial irradiation.


Neurology | 1993

MRI changes in intracranial hypotension

S. C. Pannullo; J. B. Reich; George Krol; Michael D. F. Deck; Jerome B. Posner

We report seven patients with the syndrome of intracranial hypotension who were referred to Memorial Sloan-Kettering, primarily because of suspicion of meningeal tumor or infection raised by the finding of meningeal enhancement on MRI. In three patients, symptoms occurred after lumbar puncture; in four, there was no clear precipitating event. Lumbar puncture after MRI in six patients revealed low CSF pressure (six patients) and pleocytosis or high protein, or both (four patients). Three patients had subdural effusions. Six patients had measurable descent of the brain on midsagittal images. Postural headache resolved in all seven patients, six of whom had follow-up MRIs. Meningeal enhancement resolved or diminished in all six. Subdural effusions resolved spontaneously in two and were evacuated (but were not under pressure) in one. Downward brain displacement improved or resolved in all patients. The clinical syndrome and MRI abnormalities generally resolve on their own. An extensive workup is not helpful and may be misleading. Patients should be treated symptomatically.


Neurosurgery | 2000

An Integrated Functional Magnetic Resonance Imaging Procedure for Preoperative Mapping of Cortical Areas Associated with Tactile, Motor, Language, and Visual Functions

Joy Hirsch; Maximilian I. Ruge; Karl H. S. Kim; Denise D. Correa; Jonathan D. Victor; Norman Relkin; Douglas Labar; George Krol; Mark H. Bilsky; Mark M. Souweidane; Lisa M. DeAngelis; Philip H. Gutin

OBJECTIVETo evaluate an integrated battery of preoperative functional magnetic resonance imaging (fMRI) tasks developed to identify cortical areas associated with tactile, motor, language, and visual functions. METHODSSensitivity of each task was determined by the probability that a targeted region was activated for both healthy volunteers (n = 63) and surgical patients with lesions in these critical areas (n = 125). Accuracy of each task was determined by the correspondence between the fMRI maps and intraoperative electrophysiological measurements, including somatosensory evoked potentials (n = 16), direct cortical stimulation (n = 9), and language mapping (n = 5), and by preoperative Wada tests (n = 13) and visual field examinations (n = 6). RESULTSFor healthy volunteers, the overall sensitivity was 100% for identification of the central sulcus, visual cortex, and putative Wernicke’s area, and 93% for the putative Broca’s area (dominant hemisphere). For patients with tumors affecting these regions of interest, task sensitivity was 97% for identification of the central sulcus, 100% for the visual cortex, 91% for the putative Wernicke’s area, and 77% for the putative Broca’s area. These sensitivities were enhanced by the use of multiple tasks to target related functions. Concordance of the fMRI maps and intraoperative electrophysiological measurements was observed whenever both techniques yielded maps and Wada and visual field examinations were consistent with fMRI results. CONCLUSIONThis integrated fMRI task battery offers standardized and noninvasive preoperative maps of multiple critical functions to facilitate assessment of surgical risk, planning of surgical routes, and direction of conventional, intraoperative electrophysiological procedures. Thus, a greater range of structural and functional relationships is brought to bear in the service of optimal outcomes for neurosurgery.


Neurology | 1990

Primary CNS lymphoma: combined treatment with chemotherapy and radiotherapy.

Lisa M. DeAngelis; Joachim Yahalom; Murk-Hein Heinemann; Constance Cirrincione; Howard T. Thaler; George Krol

Primary central nervous system lymphoma (PCNSL), an uncommon tumor, is occurring with increasing frequency. Conventional therapy with corticosteroids and cranial radiotherapy (RT) usually gives a dramatic initial response, but median survival is only 10 to 18 months. Chemotherapy is more successful in comparable systemic lymphoma and has been employed for PCNSL at relapse, causing remission but not cure. Between June 1985 and June 1988, we prospectively staged 32 patients with PCNSL at Memorial Sloan-Kettering Cancer Center and treated 28 on a new protocol that combined chemotherapy and radiotherapy at diagnosis. None had occult systemic lymphoma, but 19% had ocular and 69% had definite or probable leptomeningeal lymphoma. There were no complications in 19 stereotactic biopsies, but 4/10 patients who had a complete resection suffered a severe postoperative deficit. Four patients received RT alone, and 28 received chemotherapy and cranial RT, 17 of whom (group A) received a combination regimen using pre-RT systemic (1 g/m2) and intra-Ommaya methotrexate (MTX), 4,000 cGy whole-brain RT with a 1,440 cGy boost, and 2 courses of post-RT high-dose cytosine arabinoside; 5 other patients received an identical regimen but with a decreased dose of MTX (200 mg/m2). Sixty-three percent of assessable patients had a response to MTX independent of corticosteroid and prior to RT. Eighteen of 26 (69%) assessable patients who received combined therapy are alive with a median follow-up of 25.4 months. Twelve of 16 (75%) assessable group A patients are alive in the same period. Chemotherapy-related toxicity was minimal, and no late toxicities have occurred to date. A vigorous multimodality approach to PCNSL was well tolerated, and survival is markedly improved over conventional therapy.


Neurology | 1996

Low-grade oligodendroglioma responds to chemotherapy

Warren P. Mason; George Krol; Lisa M. DeAngelis

Article abstract-We administered chemotherapy in standard and intensified formulations of procarbazine, lomustine (CCNU), and vincristine to nine symptomatic patients with low-grade oligodendroglioma. Eight patients were treated with chemotherapy at presentation and one was treated for a recurrence after radiotherapy had failed. All patients improved by clinical or MRI criteria, or both. No patient deteriorated while in therapy and the responses were sustained without radiotherapy for a median of 35 months (range, 22-45) in all surviving patients treated at presentation. Chemotherapy was well tolerated; all patients developed myelosuppression, but only those receiving the intensified regimen required dose reduction or premature discontinuation of treatment. As with recurrent and anaplastic oligodendroglioma, low-grade oligodendroglioma responds to chemotherapy. NEUROLOGY 1996;46: 203-207


Neurosurgery | 1988

Combined treatment of osteosarcoma of the spine.

Narayan Sundaresan; Gerald Rosen; Andrew G. Huvos; George Krol

We reviewed the clinical features and results of treatment in 24 patients with osteogenic sarcoma of the spine treated over a 35-year period. There were 14 male and 10 female patients 13 to 71 years old. The tumor arose de novo in 13 patients and was secondary to other conditions in 11. All patients presented with pain, and 16 (67%) had neurological deficits. Patients were divided into two treatment groups. Thirteen patients treated from 1949 to 1977 usually underwent limited tumor resection and external radiation therapy. The second group, 11 patients treated from 1978 to 1984, underwent more aggressive surgical resection and received combination chemotherapy as well as local radiation to the tumor bed. In the second group, there were 5 long term survivors, and only 1 patient developed metastatic disease while on therapy. Failure to obtain local control was the major cause of treatment failure. Complete surgical resection of the tumor by spondylectomy and combination chemotherapy offer the best prospect for cure of osteogenic sarcoma of the spine.


Pediatric Neurosurgery | 1999

Brain mapping in sedated infants and young children with passive-functional magnetic resonance imaging.

Mark M. Souweidane; K.H.S. Kim; R. McDowall; Maximilian I. Ruge; E. Lis; George Krol; Joshua A. Hirsch

Functional magnetic resonance imaging (fMRI) in pediatric patients presents a unique set of problems due to the need for patient compliance, the frequent need for sedation and an early developmental status. A new method for using fMRI in sedated infants and young children is presented using passive stimuli focused on visual, sensorimotor and language functions. All of these stimuli are presented such that no patient interaction is required. Eight sedated children undergoing diagnostic MRI scans of the brain participated in these passive fMRI procedures. Cortical regions were identified using standard techniques applied to the blood-oxygen-level-dependent signal which is the basis for fMRI. The results support the feasibility of brain mapping in sedated children with passive fMRI techniques.


Journal of Neuro-oncology | 1989

The combined use of radiation therapy and lonidamine in the treatment of brain metastases.

Lisa M. DeAngelis; Violante Currie; Jae-Ho Kim; George Krol; Maureen O'Hehir; Fouad M. Farag; Charles W. Young; Jerome B. Posner

SummaryLonidamine is an indazole carboxylic acid that has been shown to be synergistic with radiotherapy (RT) in tissue culture and animal models. Clinical experience has shown that lonidamine is well-tolerated, and appears to potentiate the activity of conventional chemotherapy in the treatment of brain metastases. A prospective randomized trial was undertaken to evaluate the use of lonidamine in combination with RT in the treatment of brain metastases. All patients received 3000 cGy of whole brain radiotherapy (WBRT). Fifty eight patients were enrolled; 31 received lonidamine plus WBRT and 27 received WBRT alone. There was no significant difference in response rate or survival between the treatment groups. Lonidamine blood levels were measured in 30 of the 31 patients who received the drug, and were therapeutic (⩾ 15 μg/ml) in 50%. Survival and response rate were unaffected by the presence or absence of a therapeutic lonidamine level. The most common side-effects of lonidamine were myalgia, testicular pain, anorexia, and ototoxicity; however, only 2 patients had to discontinue the drug because of intolerable myalgias. No serious organ toxicity or myelosuppression was observed.


Neurology | 1983

CT of the brachial plexus in patients with cancer

Terrence L. Cascino; Shashidar Kori; George Krol; Kathleen M. Foley

To assess the usefulness of CT, we reviewed 51 patients with clinically diagnosed brachial plexopathy who were seen between 1977 and 1981. The established etiology was metastatic tumor in 46 and radiation fibrosis in 5. CT was abnormal in 89% of tumor patients. Myelography, bone scan, and plain cervical spine radiographs were less useful. In four of five patients with radiation fibrosis, CT showed distortion of normal tissue planes without a discrete mass, but was not always distinguishable from tumor infiltration. CT of the brachial plexus provides the best two-dimensional view of tumor infiltration and detects bony changes earlier than standard radiographs. CT is a useful guide for surgical exploration of the brachial plexus, but does not differentiate tumor infiltration from radiation fibrosis.


Neurosurgery | 2006

Use of diffusion weighted magnetic resonance imaging in predicting early postoperative outcome of new neurological deficits after brain tumor resection.

Raja B. Khan; Philip H. Gutin; Shesh N. Rai; Lijun Zhang; George Krol; Lisa M. DeAngelis

OBJECTIVE To study risk factors for the development of postoperative neurological deficits after brain tumor resection and to define prognostic factors for recovery. METHODS We prospectively studied 82 brain tumor patients undergoing tumor resection. Pre- and postoperative neurological examination, functional and performance status, cancer treatment, cardiovascular risk factors, seizure history, and blood pressure and oxygen saturation were recorded perioperatively. Postoperative magnetic resonance imaging scans were obtained within 72 hours of surgery, and the radiologist was blinded to the patients status. Abnormalities on magnetic resonance diffusion weighted images were classified as new if they extended beyond the tumor cavity margins and were absent before surgery. RESULTS Of the 80 assessable patients, 24 had a new or increased postoperative deficit by at least one point on the National Institutes of Health Stroke Scale. Presence of preoperative neurological deficits predicted development of postoperative deficits, whereas a new diffusion weighted imaging lesion after craniotomy predicted incomplete recovery of a new postoperative deficit. CONCLUSION Postoperative diffusion magnetic resonance imaging is useful in predicting early functional recovery from new deficits after brain tumor surgery.

Collaboration


Dive into the George Krol's collaboration.

Top Co-Authors

Avatar

G Sze

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Lisa M. DeAngelis

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Narayan Sundaresan

Icahn School of Medicine at Mount Sinai

View shared research outputs
Top Co-Authors

Avatar

Robert D. Zimmerman

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Ehud Arbit

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Eric Lis

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Jerome B. Posner

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Joseph H. Galicich

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Mark H. Bilsky

Memorial Sloan Kettering Cancer Center

View shared research outputs
Top Co-Authors

Avatar

Andrew G. Huvos

Memorial Sloan Kettering Cancer Center

View shared research outputs
Researchain Logo
Decentralizing Knowledge