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Biomedical subjects

G Krol

Publications and source records attributed to G Krol.

At least 19 recordsLinked to original sources
PubMed2000

An integrated functional magnetic resonance imaging procedure for preoperative mapping of cortical areas associated with tactile, motor, language, and visual functions.

OBJECTIVE: To 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. METHODS: Sensitivity 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). RESULTS: For 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. CONCLUSION: This 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.

Adolescent↗
PubMed1999

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

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.

Anesthesia↗
PubMed1997

Management of tumors of the thoracolumbar spine.

Current improvements in radiologic imaging and surgical instrumentation have greatly expanded the role of surgery in management of tumors of the thoracolumbar junction. For primary malignant tumors, the aim of surgery should be curative, with eradiction of all gross disease. For metastatic tumors, indications for surgery include cancer therapy, stabilization, neurologic palliation, tissue diagnosis, and pain relief. Because the thoracolumbar region is a transitional zone, surgical stabilization may require anterior-posterior approaches and instrumentation.

Combined Modality Therapy↗
PubMed1996

Balancing service and education: improving internal medicine residencies in the managed care era.

BACKGROUND: Internal medicine training programs must adapt to health care systems faced with balancing the competitive priorities of patient-care responsibilities and educational needs. OBJECTIVE: To evaluated the effects of a major organizational change on the inpatient service of an internal medicine residency program in a vertically integrated health system. METHODS: We changed the structure of our program from a system in which the hospitalized patients' primary physicians were responsible for daily inpatient management, while teaching was assigned to a defined teaching rounder, to a method in which the rounding attending was responsible for both teaching and patient care. Measurements before and after the change in the rounding system included: the McGill University clinical tutor evaluations, time-motion observations of house staff, patient satisfaction surveys, average length of stay data, and physician focus groups to assess physician satisfaction. RESULTS: The rounding attendings consistently received excellent to superior ratings by the house staff both before and after the implemented change. Compared to time-motion observations performed before the change, observations recorded after the change suggested that a greater percent of house staff time was spent on educational activities. The responses of patient satisfaction surveys indicated that the perception of quality of care remained high after the system change. Lastly, the average length of stay for patients on the general internal medicine and subspecialty services was reduced from 7.6 days before the change to 6.6 days after the change, a difference of 0.92 day (95% confidence interval 1.3 to 0.6, P < 0.001). CONCLUSIONS: Through organizational restructuring, it is possible to improve the quality of patient care and improving the efficiency of patient-care management.

Hospital Bed Capacity, 500 and over↗
PubMed1996

Indications and results of combined anterior-posterior approaches for spine tumor surgery.

Spinal instrumentation currently allows gross-total resection and reconstruction in cases of malignancies at all levels of the spine. The authors analyzed the results in 110 patients who underwent surgery for primary and metastatic spinal tumors over a 5-year period (1989-1993) at a single institution. Major primary sites of tumor included breast (14 cases), chordoma (14 cases), lung (12 cases), kidney (11 cases), sarcoma (13 cases), plasmacytoma (10 cases), and others (36 cases). Prior to surgery, 55 patients (50%) had received prior treatment. Forty-eight patients (44%) were nonambulatory, and severe paraparesis was present in 20 patients. Fifty-three patients (48%) underwent combined anterior-posterior resection and instrumentation. 33 (30%) underwent anterior resection with instrumentation, 18 (16%) underwent anterior or posterior resection alone, and the remaining six patients (5%) underwent posterior resection and instrumentation. Major indications for anterior-posterior resection included three-column involvement, high-grade instability, involvement of contiguous vertebral bodies, and solitary metastases. Postoperatively, 90 patients improved neurologically. The overall median survival was 16 months, with 46% of patients surviving 2 years. Fifty-three patients (48%) suffered postoperative complications. Despite the high incidence of complications, the majority of patients reported improvement in their quality of life at follow-up review. Our findings suggest that half of all patients with spinal malignancies require combined anterior-posterior surgery for adequate tumor removal and stabilization.

Adult↗
PubMed1996

High-dose edatrexate with oral leucovorin rescue: a phase I and clinical pharmacological study in adults with advanced cancer.

Our objective was to determine the maximum tolerated dose and toxicity of i.v. edatrexate with p.o. leucovorin. Thirty-one adults with advanced solid tumors received edatrexate as a 2-h infusion, once a week for 3 weeks, recycled every 28 days. p.o. leucovorin (10 mg/m2, every 6 h for 10 doses) began 24 h later. All had urinary alkalinization and p.o. hydration. Nine dosage levels ranging from 120 to 3750 mg/m2 were explored. Fatigue, epistaxis, nausea/emesis, mucositis, rash, myalgias, leukopenia, thrombocytopenia, and transient elevations of serum aspartate transferase were observed. Leukoencephalopathy with clinical manifestations occurred in two patients (one had prior cranial irradiation). Pharmacokinetic studies carried out at the 120- and 1080-mg/m2 dose levels revealed no significant difference in the elimination half-life at the two dose levels studied and no significant intrapatient variability between day 1 and day 8 edatrexate administration. Serum edatrexate levels measured using a dihydrofolate reductase inhibition assay correlated with those by high-performance liquid chromatography. Three major and two minor antitumor responses occurred. The maximum tolerated dose was 3750 mg/m2, with grade 3 or 4 leukopenia (one patient), stomatitis (one patient), and leukoencephalopathy (one patient). Because of the occurrence of leukoencephalopathy, further study of high-dose edatrexate with leucovorin rescue is not recommended.

Administration, Oral↗
PubMed1995

Neuroimaging and cerebrospinal fluid cytology in the diagnosis of leptomeningeal metastasis.

The diagnosis of leptomeningeal metastasis is often difficult and usually requires the demonstration of malignant cells in the cerebrospinal fluid. Neuroimaging, however, may establish or support the diagnosis in some patients. Radiographic abnormalities consistent with or suggestive of leptomeningeal metastasis include leptomeningeal, subependymal, dural, or cranial nerve enhancement; superficial cerebral lesions; and communicating hydrocephalus. We evaluated 137 cancer patients with clinical symptoms suspicious for leptomeningeal metastasis with neuroimaging or cerebrospinal fluid cytology or both. Neuroimaging findings were abnormal in 70 of 128 tested patients; cytology was performed in 58 of these 70 and the results were positive in 37. Conversely, cytological findings were positive in 53 of 115 tested patients; neuroimaging was performed in 49 of these 53 and the findings were abnormal in 37 (26/29 solid tumors and 11/20 hematological tumors). Of the total series of 137 patients, leptomeningeal metastasis was diagnosed in 77; in 24 (31%) the diagnosis was made on the basis of clinical picture and abnormal neuroimaging alone. Neuroimaging is a valuable tool in the investigation of leptomeningeal metastasis in the cancer population, and the presence of typical clinical features together with appropriate neuroimaging abnormalities is adequate to make the diagnosis of leptomeningeal metastasis even if cerebrospinal fluid cytological results are negative.

Adolescent↗
PubMed1995

Primary amyloidoma of the brain: CT and MR presentation.

We present CT and MR imaging studies of a histologically proved case of a primary intraaxial amyloidoma of the brain. Noncontrast CT and T1-weighted MR images revealed increased density and hyperintensity respectively of amyloid tissue. There was mixed intensity on proton-density and T2-weighted sequences, and marked contrast enhancement was demonstrated on both modalities.

Amyloidosis↗
PubMed1993

MRI changes in intracranial hypotension.

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.

Adult↗
PubMed1993

Rebound caloric nystagmus.

Rebound caloric nystagmus (RCN), a distinctly different phenomenon from secondary phase nystagmus (SPN), was serendipitously discovered during the course of routine neurotological evaluations. RCN occurred when the horizontal semicircular canal was brought into a truly horizontal plane after the primary phase nystagmus (PPN) had ended. The maximum slow-phase velocities (SPVMax) of both PPN and RCN were almost identical. The pathological lesion was an Arnold-Chiari malformation (ACM). Two other patients with posterior fossa lesions also showed RCN. To determine if RCN is an unrecognized normal phenomenon, 11 healthy subjects were tested. The average SPV of RCN in normals was 0.7 degrees per second. Such a small value of RCN is probably of no significance. It therefore appears that RCN is a sign of posterior fossa neuroaxial lesions.

Adult↗
PubMed1993

Percutaneous lateral cervical cordotomy: target localization with water-soluble contrast medium.

Water-soluble intrathecal contrast material was used for radiographic identification of the cord target in 13 patients undergoing percutaneous lateral cervical cordotomy. Adequate visualization of the dentate ligament, considered essential for successful placement of the electrode, was achieved in seven cases. In the remaining six patients, four with suboptimal definition and two with nonvisualization of the ligament, an additional injection of contrast medium using a modified coaxial needle system outlined the entire thickness of the cervical cord. This technique improved needle-tip positioning in relation to the cord and resulted in successful surgery in all six patients.

Contrast Media↗
PubMed1992

Spinal epidural tumor in patients with prostate cancer. Clinical and radiographic predictors of response to radiation therapy.

The authors retrospectively reviewed 50 episodes of spinal epidural tumor that occurred in 42 patients with metastatic prostate cancer and were treated with external-beam radiation. Treatment response was evaluated in terms of symptoms, neurologic status, and, in most cases, reduction of tumor on repeat myelography. At the completion of therapy, 92% of treated patients experienced pain relief and 67% had significant to complete improvement on neurologic examination. Thirty days after treatment, repeat myelography was performed in 40 of the 50 cases; compared with the initial findings immediately preceding radiation therapy (RT), the results of 58% of these studies had normalized completely, results were improved in 25%, and the results had not changed in 18%. The presence of a high-grade compression fracture of the vertebral body was an indicator of poor prognosis for tumor response on repeat myelography. The ability of a patient to walk before treatment and tumor response on repeat myelography were associated significantly with improved outcome of RT and with survival. The authors conclude that RT can effectively palliate epidural lesions from metastatic prostate cancer. The prognosis for the long-term response to therapy may be indicated by pretreatment ambulatory status and posttreatment imaging of the epidural space.

Adenocarcinoma↗
PubMed1992

Occult epidural chloroma complicated by acute paraplegia following lumbar puncture.

Acute paraplegia complicating lumbar puncture in a leukemic patient with an unsuspected epidural chloroma is described, including the postmortem findings. Lumbar puncture can precipitate irreversible injury to the spinal cord in the patient with an occult lesion causing subarachnoid block. This account, in addition to documenting this phenomenon, suggests a potential advantage to magnetic resonance imaging over myelography.

Acute Disease↗
PubMed1992

Binocular infrared oculography.

A new system of infrared oculography has been developed which provides binocular recordings and allows simultaneous measurement of horizontal and vertical eye movements. The sensitivity of the system is 1 minute of arc, and it has a horizontal range of +/- 30 degrees and a vertical range of +/- 20 degrees. Using this system for routine clinical evaluations, it was possible to record divergent spontaneous nystagmus and divergent thermally induced nystagmus. Rotatory nystagmus can also be recorded. The binocular infrared oculographic system (BIRO) satisfies nearly all the requirements of an ideal recording system.

Brain Ischemia↗
PubMed1991

Percutaneous radiofrequency neurolysis guided by computed tomography for the treatment of glossopharyngeal neuralgia.

The technique of radiofrequency neurolysis guided by computed tomography for the treatment of glossopharyngeal neuralgia is described. This technique has the advantage of being performed in a neutral head position, affording excellent visualization of the jugular foramen, and also of simulating radiographically the precise trajectory of the electrode. This procedure is of particular value in treating patients with neoplastic disease and those in whom the outlines of the jugular foramen are poorly visualized on fluoroscopy or plain radiography.

Aged↗
PubMed1990

Decompression of epidural metastases from germ cell tumors with chemotherapy.

Epidural cord compression from germ cell tumor metastases is not common. Treatment usually requires high dose corticosteroids with radiation therapy and/or surgical decompression. Three patients with epidural germ cell tumor metastases were treated with cisplatin-based chemotherapy and all three had complete neurologic recovery. Systemic chemotherapy should be considered as initial therapy with corticosteroids for epidural cord compression from metastatic germ cell tumor.

Adult↗
PubMed1990

Primary CNS lymphoma: combined treatment with chemotherapy and radiotherapy.

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.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗