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G R Cosgrove

Publications and source records attributed to G R Cosgrove.

At least 37 records · Page 2Linked to original sources
PubMed1998

Accuracy of electroencephalographic dipole localization of epileptiform activities associated with focal brain lesions.

We evaluated the accuracy of an electroencephalographic (EEG) localization technique (dipole inverse solution) in a consecutive series of 12 focal intracerebral lesions of diverse etiologies whose EEGs showed interictal spike activity or rhythmic activity at seizure onset. The calculated equivalent dipole was plotted on three axes in the patients' magnetic resonance image, and the distance between the dipole and the lesion margin was measured assuming that the shell of the lesion constituted an epileptogenic region. In all cases the dipole localized closer than 0.8 cm to the nearest lesion margin. In addition, we compared the postsurgical outcome of 6 patients to the dipole localization and the resection margins. In all 6 patients in whom the dipole, and hence the estimated seizure generator, was removed the surgical outcome was favorable. We conclude that the inverse solution algorithm is a promising method for using the scalp EEG to localize the sources of electrical activity in the human brain in routine clinical electroencephalography and provides three-dimensional data not available from conventional analysis.

Adult↗
PubMed1998

A mobile computed tomographic scanner with intraoperative and intensive care unit applications.

INTRODUCTION: A mobile computed tomographic scanner has been developed in which the scan plane is selected by means of gantry translation, rather than by translation of the patient table. This permits computed tomographic scanning in situ of any patient who is positioned on a radiolucent surface that fits within the inner diameter of the gantry. We report the design of and initial experience with this scanner as used with adapters for intraoperative and bedside computed tomography (CT). METHODS: The scanner is equipped with wheels, draws power from wall outlets (120 V, 20 A) in combination with batteries, and has a translating gantry. Preclinical studies of image quality were performed with phantoms. An operating table adapter was built for use with a radiolucent cranial fixation device. A bedside adapter was built that holds the head and shoulders of a patient in the intensive care unit. RESULTS: The preclinical phantom studies showed satisfactory image spatial resolution (0.8 mm) and low-contrast resolution signal-to-noise relative standard deviation (0.37%). Experience to date with 12 patients has confirmed the feasibility of intraoperative CT on demand. Experience to date with 26 patients has confirmed the feasibility of routine bedside CT in the intensive care unit. CONCLUSION: With these adaptations, mobile CT may increase the efficiency of intraoperative scanning by making it available to multiple operating rooms without committing it to any room for an entire operation and may increase the efficiency and safety of CT of critically ill patients who currently need to leave the intensive care unit to travel to a fixed CT installation and back.

Child↗
PubMed1998

Familial meningioma: analysis of expression of neurofibromatosis 2 protein Merlin. Report of two cases.

Meningiomas are primarily benign brain tumors thought to arise through multistep tumorigenesis, involving both the activation of oncogenes and the loss of tumor suppressor genes. The recently isolated neurofibromatosis 2 (NF2) tumor suppressor gene has been found to be mutated in a large proportion of meningiomas. Almost all cases of familial meningioma occur in association with NF2. Familial meningioma in isolation from NF2 (sporadic) is exceedingly rare, with only 14 reports since 1959. The authors report the existence of a family lacking any stigmata of NF2, in which two members had spinal meningiomas. Tumor specimens were subjected to immunocytochemical analysis for the NF2 protein product Merlin, which has been implicated in the tumorigenesis of meningioma. Merlin immunoreactivity was present in both tumor specimens, implying that the NF2 tumor suppressor gene was not deleted in these tumors. This supports the hypothesis that a second tumor suppressor gene locus, other than NF2, acts in the formation of familial sporadic meningioma. The results are discussed in the context of putative oncogenic mechanisms of familial meningiomas.

Adult↗
PubMed1998

The importance of accurate lesion placement in posteroventral pallidotomy. Report of two cases.

Pallidotomy has become a widely used treatment for medically refractory Parkinson's disease. However, the optimal lesion size and location within the pallidum have not yet been determined, and the role of repeated pallidotomy remains undefined. The authors present two patients who had unsatisfactory results after their first unilateral pallidotomy but attained dramatic and long-lasting improvement with repeated surgery. The results obtained in these cases indicate that patients who have a good clinical outcome initially but relapse rapidly after surgery should be considered for repeated pallidotomy if the initial lesion was not placed in the optimal location.

Aged↗
PubMed1998

Readiness of critical care physicians and nurses to handle requests for organ donation.

BACKGROUND: Critical care nurses and physicians usually care for those patients whose condition progresses to brain death and are also often responsible for requesting organ donation from the family of a brain-dead patient. We hypothesized that staff support, knowledge, and training levels would be significantly associated with organ donation rates. OBJECTIVE: To assess the readiness of critical care staff to successfully handle requests for organ donation. METHODS: A total of 1061 critical care staff from 28 hospitals in four separate regions of the United States completed a questionnaire that assessed (1) factual knowledge about organ donation, (2) understanding of brain death, (3) previous training in procedures for requesting donations, and (4) comfort levels with the donation process. RESULTS: Staff training in effective procedures for requesting organ donations was significantly correlated with hospitals' donation rates. Less than a third of respondents, however, had received training in explaining brain death to and requesting organ donation from a grieving family. In hospitals with high rates of organ donation, 52.9% of staff had received training; in hospitals with low rates of organ donation, 23.5% of staff had received training. Levels of factual knowledge about organ donation and brain death were unexpectedly low but were not significantly related to hospitals' rates of organ donation. CONCLUSIONS: Training of critical care nurses and physicians in effective procedures for requesting organ donation is significantly associated with higher rates of organ donation, yet two thirds of critical care staff report no relevant training. Consequently, critical care staff cannot be considered ready to effectively handle requests for organ donation.

Attitude of Health Personnel↗
PubMed1998

Cortical activation MR studies in brain disorders.

Principles and clinical applications of functional MR imaging activation studies are presented. The physical and physiologic basis for cerebral blood volume-, cerebral blood flow-, and oxygenation-based functional MR imaging techniques are reviewed. The methodology of blood oxygen level dependent (BOLD) functional MR imaging is emphasized. Applications to presurgical mapping of sensorimotor and language function in patients with vascular malformations, tumors, and other lesions near critical cortical areas are illustrated. Important new applications to neuropsychiatric diseases are highlighted.

Blood Volume↗
PubMed1997

Neurosurgical treatment of neuropsychiatric illness.

Neurosurgical treatment of neuropsychiatric illness has evolved considerably since its inception in 1935. The most common psychiatric indications for the procedure, including obsessive-compulsive disorder and major depression, are conceptualized as disorders involving the basal ganglia and limbic system. In this article, the various operations and their contemporary applications are discussed. Neurosurgical treatment represents a viable option in appropriate candidates suffering from severe and otherwise treatment-refractory neuropsychiatric diseases.

Basal Ganglia↗
PubMed1997

Cerebral arterial ectasia and tuberous sclerosis: case report.

OBJECTIVE AND IMPORTANCE: Tuberous sclerosis is associated with a wide variety of central nervous system abnormalities. Cerebrovascular anomalies are extremely rare, but a case of cerebral arterial ectasia and giant fusiform aneurysm formation in a young child is reported. CLINICAL PRESENTATION: A 5-month-old male patient with tuberous sclerosis presented with seizures, a subependymal tumor, and intraventricular hemorrhage. Cerebral angiography demonstrated a large fusiform aneurysm of the left cavernous internal carotid artery as well as arterial ectasia of the proximal left anterior cerebral and middle cerebral arteries. The patient developed hydrocephalus and died of infectious complications after repeated shunt procedures. CONCLUSION: Tuberous sclerosis is commonly associated with central nervous system lesions. Although rare, cerebrovascular anomalies and aneurysms should be considered in the differential diagnosis of mass lesions to avoid an ill-advised biopsy of a vascular lesion, which could have disastrous consequences.

Cerebral Angiography↗
PubMed1997

Interstitial irradiation of brain tumors, using a miniature radiosurgery device: initial experience.

OBJECTIVE: This report describes the clinical evaluation of a novel stereotactic radiosurgical device for interstitial irradiation of malignant brain tumors. METHODS: Fourteen patients with cerebral lesions less than 3.5 cm in greatest diameter were treated with a single fraction of stereotactic interstitial irradiation (average, 12.5 Gy). Clinical evaluation, Karnofsky Performance Scale ratings, and neuroimaging studies were obtained at 6-week intervals postoperatively to assess treatment response. Reduction or stabilization of tumor size on follow-up imaging was accepted as local control, whereas tumor enlargement indicated local failure. INSTRUMENTATION: This battery-powered miniature x-ray generator device produces low-energy x-ray photons that are attenuated rapidly within tissue. A dose decline rate proportional to 1/r3 yields extremely sharp dose fall-off curves with minimal exposure to surrounding tissue. Dose rates of 200 cGy per minute are possible, allowing for the administration of 12.5 Gy to a lesion 3 cm in diameter in less than 1 hour. RESULTS: Local control (stabilization or reduction in lesion size) was obtained in 10 of the 13 patients with tumors with follow-up of 1.5 to 36 months (mean, 12 mo). Of three patients with radiographic progression, recurrence was symptomatic in only one. All patients tolerated the procedure well, and most patients were discharged home the day after treatment. No new neurological deficits were noted after biopsy and irradiation. CONCLUSIONS: Preliminary experience with this novel radiosurgical device has demonstrated its feasibility and safety. Clinical efficacy of this technique is now under investigation in an international multicenter study.

Adult↗
PubMed1997

Stereotactic transcranial magnetic stimulation: correlation with direct electrical cortical stimulation.

OBJECTIVE: To evaluate stereotactic transcranial magnetic stimulation (TMS) as a tool for presurgical functional mapping of human motor cortex. METHODS: Transcranial magnetic stimulation using a frameless stereotactic system was performed in two patients with tumors near the central sulcus. TMS motor function maps were plotted on the patients' three-dimensional volumetric magnetic resonance imaging data and compared with direct electrical cortical stimulation at surgery with the patient under local anesthesia. RESULTS: Stereotactic TMS was well tolerated by both patients and was consistent with known somatotopic representation of human motor cortex. The results demonstrated a good correlation between the TMS and electrical cortical stimulation maps, with all TMS responses eliciting more than 75% of the maximum motor evoked potential falling within 1 cm of the electrical cortical stimulation site. CONCLUSIONS: Our findings indicate that stereotactic TMS is feasible and can provide accurate noninvasive localization of cortical motor function. It may prove to be a useful method for presurgical planning.

Adult↗
PubMed1997

Functional magnetic resonance imaging and transcranial magnetic stimulation: complementary approaches in the evaluation of cortical motor function.

Functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) represent different approaches to mapping the motor cortex. fMRI identifies areas of hemodynamic changes during task performance while TMS provides electrophysiologic data concerning the localization and density of cortical motoneurons. Here we define the spatial correlation between fMRI and TMS maps and compared them with direct electrical cortical stimulation (ECS). We performed fMRI at 1.5 T on 3 normal subjects and 2 patients with mass lesions near the central sulcus using a multislice, asymmetric, spin-echo, echo-planar pulse sequence during the performance of a motor task. We also performed focal TMS with surface EMG recordings from the muscles primarily involved in the fMRI task. We coregistered the stimulation sites in real time with the fMRI maps using a frameless stereotactic system. In both patients we also performed ECS of the cortex during surgery under local anesthesia. fMRI maps were validated by the electrophysiologic data both pre- and intraoperatively. Our results suggest that regions of fMRI activation correspond spatially to areas of highest motoneuron density as demonstrated by electrophysiologic techniques.

Adult↗
PubMed1997

Location of language in the cortex: a comparison between functional MR imaging and electrocortical stimulation.

PURPOSE: To determine the accuracy of functional MR imaging in locating language areas for planning surgical resection. METHODS: Intraoperative photographs were digitized and overlaid on functional MR language maps. The sensitivity and specificity of functional MR imaging for identifying language areas were determined for five different language tasks by comparing functional MR areas of language activation with results of electrocortical stimulation. A match was considered to occur if an activated area contacted overlapped, or surrounded a language tag. The borders of the activation areas were extended by 1 and 2 cm to determine whether the number of matches changed. Language and nonlanguage tag matches were tabulated separately. RESULTS: Sensitivity/specificity for all patients and all language tasks ranged from 81%/53% for areas that touched to 92%/0% for areas separated by 2 cm. Individual language tasks were not as sensitive as a battery of language tasks combined. Location of language areas varied among subjects for a given task and among tasks for a given subject. CONCLUSION: Functional MR imaging should be considered a useful presurgical planning tool for mapping cortical language areas, because it is sensitive, it provides increased time for planning before surgery, and it is noninvasive.

Brain Diseases↗
PubMed1996

Functional MRI localization of language in a 9-year-old child.

BACKGROUND: Localizing critical brain functions such as language in children is difficult and generally requires invasive techniques. Recently sensory, motor and language functions in adults have been mapped to specific brain locations using functional imaging techniques. Of these techniques, functional MRI (fMRI) is the least invasive and has the highest spatial and temporal resolution. Its use in adults is well documented but application to children has not been as well described. In the present study lateralization and localization of language was evaluated with fMRI prior to epilepsy surgery in a nine-year-old male with complex partial seizures, attentional difficulty and decreased verbal proficiency. METHODS: Two language paradigms well studied in adults (read, verb generation) and two additional language paradigms (antonym generation, latter fluency) were studied using whole brain fMRI after stimulus items and timing were adjusted to achieve the desired performance level during imaging. The patient was also conditioned to the magnet environment prior to imaging. RESULTS: Word reading and letter fluency tasks produced lateralized and localized activation similar to that seen in adults. The patient had no language deficits following an anterior 2/3 dominant temporal lobe resection. CONCLUSIONS: With modifications of protocols such as those detailed in this report, this non-invasive method for localizing language function is feasible for the presurgical evaluation of children as well being applicable for a variety of developmental language issues.

Brain↗
PubMed1996

Delayed complications thirty-six years after hemispherectomy: a case report.

PURPOSE: To describe a late complication of hemispherectomy in a patient in whom symptoms of hydrocephalus developed 36 years after her left-sided hemispherectomy, the longest delay on record. METHODS: Hemispherectomy has been successfully used in the treatment of intractable epilepsy associated with infantile-type hemiplegia for a half century. Of the patients, however, up to 33% have late increased cerebrospinal fluid pressure complications attributed to superficial cerebral hemosiderosis. Through a retrospective case analysis, we describe such complications in a 52-year-old woman with cognitive impairment, gait instability, urinary incontinence, and right hemineglect 36 years after her initial procedure. RESULTS: Quantitative, objective measures of cognition and gait-laboratory testing confirmed the patient's favorable clinical response to ventriculoperitoneal shunting, as well as the complete resolution of her symptoms, including the atypical occurrence of right-sided hemineglect. CONCLUSIONS: This case uniquely demonstrates the clinical features of a late complication of hemispherectomy while documenting the longest reported delay for developing such adverse sequelae. We also emphasize the need for more extensive follow-up studies to assess the extent of posthemispherectomy complications.

Brain↗
PubMed1996

Functional magnetic resonance imaging for intracranial navigation.

Functional MR imaging can provide accurate anatomic and physiologic localization of human cortical function. This new method of noninvasive cortical mapping appears to be valuable preoperatively for risk assessment, therapeutic decision making and surgical planning. The integrated volume rendering of brain surface topography, cortical veins, structural lesion, and sites of functional activation is also useful intraoperatively for defining cortical resection boundaries in patients with lesions in critical areas.

Adolescent↗
PubMed1996

Magnetic resonance image-guided stereotactic cingulotomy for intractable psychiatric disease.

We describe the modern operative technique of magnetic resonance (MR) image-guided stereotactic cingulotomy and discuss the indications, results, and complications of this procedure. A retrospective analysis of psychiatric outcome was performed for 34 patients with intractable major affective disorder and/or obsessive-compulsive disorder who underwent MR image-guided stereotactic cingulotomy since 1991. Fourteen patients underwent multiple cingulotomies (50 total procedures). Overall, 38% of the patients were classified as responders, 23% as possible responders, and 38% as nonresponders. Of the patients who did not respond to initial cingulotomies and who underwent multiple cingulotomies, 36% became responders, 36% possible responders, and 28% nonresponders. There were no deaths or long-term side effects related to the procedure. The therapeutic results of MR image-guided stereotactic cingulotomy are similar to the results of earlier methods of cingulotomy, and the use of MR imaging offers substantial technical advantages. This procedure also compares favorably with other neurosurgical procedures performed for intractable psychiatric disease with a low rate of undesired side effects. Cingulotomy is safe and well tolerated, with over one-third of the patients demonstrating significant improvement; however, prospective long-term follow-up studies are needed to further define the role of surgery in treating intractable psychiatric disease.

Adolescent↗
PubMed1996

Interstitial brachytherapy for intracranial metastases.

In large medical centers, the availability of radiosurgery has relegated brachytherapy to a lesser role in the treatment of newly diagnosed solitary brain metastases. However, the treatment planning in radiosurgery is complex, and in some case the hardware is prohibitively expensive; low or high dose rate brachytherapy requires only a stereotactic frame, commercially available software, and encapsulated radionuclides or newer tiny linear accelerators. Interstitial brachytherapy also remains an option for the treatment of recurrent solitary metastases when other forms of treatment have failed. This article reviews the radiobiology of low and high dose rate interstitial brachytherapy, the University of California San Francisco (UCSF) results using iodine-125 implants, and early experience with the photon radiosurgery system (PRS) at Massachusetts General Hospital for the treatment of brain metastases.

Adolescent↗