Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravi... more Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravity. Previous flight observations document significant facial edema during exposure to microgravity, which suggests that ICP is elevated during microgravity. However, there are no experimental results obtained during space flight, primarily due to the invasiveness of currently available techniques. We have developed and refined a noninvasive technique to measure intracranial pressure noninvasively. The technique is based upon detecting skull movements of a few micrometers in association with altered intracranial pressure. We reported that the PPLL technique has enough sensitivity to detect changes in cranial distance associated with the pulsation of ICP in cadavera. In normal operations, however, we place a transducer on the scalp. Thus, we cannot rule out the possibility that the PPLL technique picks up cutaneous pulsation. The purpose of the present study was therefore to show that the PPLL technique has enough sensitivity to detect changes in cranial distance associated with cardiac cycles in vivo.
OBJECT Demonstrating the value of spine care requires adequate outcomes assessment. Long-term out... more OBJECT Demonstrating the value of spine care requires adequate outcomes assessment. Long-term outcomes are best measured as overall improvement in quality of life (QOL) after surgical intervention. Present registries often require parallel data entry, introducing inefficiencies and limiting compliance. The authors detail the methodology of constructing an integrated electronic health record (EHR) system to collect QOL metrics and demonstrate the effect of data collection on routine clinical workflow. A streamlined approach to collecting QOL data can capture patient data without requiring dual data entry and without increasing clinic visit times. METHODS Through extensive literature review, a combination of QOL assessments was selected, consisting of the Patient Health Questionnaire-2 and -9, Oswestry Disability Index, Neck Disability Index, and visual analog scale for pain. These metrics were used to provide assessment of QOL following spine surgery and were incorporated into standard clinic workflow by a multidisciplinary team of surgeons, advanced practice providers, and health care information technology specialists. A clinical dashboard tracking more than 25 patient variables was developed. Clinic flow was assessed and opportunities for improvement reviewed. Duration of clinic visits before and after initiation of QOL measure capture was recorded, with assessment of mean clinic visit times for the 12 months before and the 12 months after implementation. RESULTS The integrated QOL capture was instituted for 3 spine surgeons in a tertiary care academic center. In the 12-month period prior to initiating collection of QOL data, 806 new patient visits were completed with an average visit time of 127.9 ± 51.5 minutes. In the 12 months after implementation, 1013 new patient visits were recorded, with 791 providing QOL measures with an average visit time of 117.0 ± 45.7 minutes. Initially the primary means of collecting patient outcome data was via paper form, with gradual transition to collection via entry into the electronic medical records system. To improve electronic data capture, paper forms were eliminated and an online portal used as part of the patient rooming process. This improved electronic capture to nearly 98% without decreasing the number of patients enrolled in the process. CONCLUSIONS A systematic approach to collecting spine-related QOL data within an EHR system is feasible and offers distinct advantages over registries that require dual data entry. The process of data collection does not impact…
Hyperglycemia has been reported to worsen the tolerance of the brain to ischemia, and it has ther... more Hyperglycemia has been reported to worsen the tolerance of the brain to ischemia, and it has therefore been recommended that patients undergoing neurosurgical procedures not receive glucose-containing solutions. However, whereas most animal studies have used global ischemia models, most neurosurgical procedures are associated with risks of focal rather than global ischemia. We therefore studied the effects of glucose administration in an animal model of focal cerebral ischemia. We anesthetized 20 cats with halothane (0.85% end tidal in oxygen), and a focal cerebral ischemic lesion was produced by clip ligation of the left middle cerebral artery using a transorbital approach. Hyperglycemia (10 cats, mean +/- SEM plasma glucose concentration 561 +/- 36 mg/dl) was established before ligation by infusion of 50% glucose in 0.45% saline; the control group (10 cats, mean +/- SEM plasma glucose concentration 209 +/- 28 mg/dl) received 0.45% saline only. Total fluid administered, mean arteri...
This study was designed to investigate effects of whole body tilting on intracranial compliance a... more This study was designed to investigate effects of whole body tilting on intracranial compliance and pressure in six healthy volunteers by using a noninvasive ultrasonic device. Subjects were randomly tilted up or down sequentially at 60 degree, 30 degree head-up, supine, and 15 degree head-down position for one minute at each angle. We measured arterial blood pressure with a finger pressure cuff and changes in intracranial distance with an ultrasonic device. The device measures skull movement on the order of micro-meter. Our ultrasound technique demonstrates that skull movement is highly correlated (r$(circumflex){2}$=0.77) with intracranial pressure variations due to cerebral arterial pulsation. The amplitudes of arterial pressure (r$(circumflex){2}$=0.99 and those of intracranial distance changes (r$(circumflex){2}$=0.87) associated with one cardiac cycle were inversely correlated with the angle of tilt. The ratio of pulsation amplitudes for intracranial distance over arterial pre...
Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravi... more Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravity. ICP may increase during microgravity due to a fluid shift to the head. As widely observed in clinical settings, elevated ICP causes headache, nausea, and projectile vomiting, which are similar to symptoms of the space adaptation syndrome. At levels over 20 millimeters mercury, ICP may compromise cerebral circulation. However, there are no experimental results to support the hypothesis that ICP is actually altered during microgravity exposure, primarily because o i the invasiveness of currently available techniques. Ames has developed and refined an ultrasonic device that measures changes in intracranial distance noninvasively using a patented pulse phase locked loop (PPLL) technique. Although the skull is assumed to be rigid, many investigators report that the skull moves on the order of micrometers in association with ICP pulsation resulting from variations in arterial pressure. The...
TiTlE ModEl SuMMAry PrESEnTEd Comparative healing of surgical incisions created by standard elect... more TiTlE ModEl SuMMAry PrESEnTEd Comparative healing of surgical incisions created by standard electrosurgery, PEAK PlasmaBlade, and standard scalpel blade
Proceedings of the National Academy of Sciences, 2015
The human brain is a tissue of vast complexity in terms of the cell types it comprises. Conventio... more The human brain is a tissue of vast complexity in terms of the cell types it comprises. Conventional approaches to classifying cell types in the human brain at single cell resolution have been limited to exploring relatively few markers and therefore have provided a limited molecular characterization of any given cell type. We used single cell RNA sequencing on 466 cells to capture the cellular complexity of the adult and fetal human brain at a whole transcriptome level. Healthy adult temporal lobe tissue was obtained during surgical procedures where otherwise normal tissue was removed to gain access to deeper hippocampal pathology in patients with medical refractory seizures. We were able to classify individual cells into all of the major neuronal, glial, and vascular cell types in the brain. We were able to divide neurons into individual communities and show that these communities preserve the categorization of interneuron subtypes that is typically observed with the use of classic interneuron markers. We then used single cell RNA sequencing on fetal human cortical neurons to identify genes that are differentially expressed between fetal and adult neurons and those genes that display an expression gradient that reflects the transition between replicating and quiescent fetal neuronal populations. Finally, we observed the expression of major histocompatibility complex type I genes in a subset of adult neurons, but not fetal neurons. The work presented here demonstrates the applicability of single cell RNA sequencing on the study of the adult human brain and constitutes a first step toward a comprehensive cellular atlas of the human brain.
Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology, 1998
It is believed that intracranial pressure (ICP) may be elevated in microgravity because a fluid s... more It is believed that intracranial pressure (ICP) may be elevated in microgravity because a fluid shift toward the head occurs due to loss of gravitational blood pressures. Elevated ICP may contribute to space adaptation syndrome, because as widely observed in clinical settings, elevated ICP causes headache, nausea, and projectile vomiting, which are similar to symptoms of space adaptation syndrome. However, the hypothesis that ICP is altered in microgravity is difficult to test because of the invasiveness of currently-available techniques. We have developed a new ultrasonic technique, which allows us to record ICP waveforms noninvasively. The present study was designed to understand postural effects on ICP and assess the feasibility of our new device in future flight experiments.
Idiopathic granulomatous inflammation of the pituitary gland occurs rarely, and is usually identi... more Idiopathic granulomatous inflammation of the pituitary gland occurs rarely, and is usually identified as an incidental finding at autopsy. However, it may present during life as a mass lesion that clinically mimics other more common pituitary gland lesions. We report a 54-year-old woman presenting with acute onset diabetes insipidus whose MRI showed a 1.1 cm pituitary mass, with infundibular thickening and meningeal enhancement. Biopsy demonstrated granulomatous hypophysitis with multinucleate histiocytes. Special studies for infectious organisms were negative. The patient's disease progressed following biopsy, causing complete loss of vision in the right eye. This responded to high-dose steroids and local lowdose radiation. She later developed an acute inferior myocardial infarction. Laboratory tests failed to demonstrate an underlying autoimmune process. While recovering from this myocardial infarction, she succumbed to pulmonary embolism. Autopsy revealed moderate residual ch...
We report two cases of central neurocytoma; one located in the right lateral ventricle and associ... more We report two cases of central neurocytoma; one located in the right lateral ventricle and associated with a distinctly separate primitive neuroectodermal tumor (PNET)/medulloblastoma of the fourth ventricle, and the other admixed with fat cells and arising from the left lateral and third ventricles with extension into the corpus callosum. We discuss that concurrent occurrences of PNET and adipose tissue are not fortuitous events, but an evidence that neurocytomas and PNETs originate in the residual germinal pool from common progenitor cell rests recapitulating features of developing neurons and with a potential for mesenchymal differentiation.
Intraoperative ultrasound (US) was compared to computed tomography (CT) in 41 intracranial and 6 ... more Intraoperative ultrasound (US) was compared to computed tomography (CT) in 41 intracranial and 6 spinal cord tumors. The studies correlated closely except for primary gliomas. Eight of the 22 primary intracranial gliomas (37%), including 1 low-grade and 7 anaplastic tumors, were larger and more extensive on US than on CT. Margins of non-enhanced primary astrocytomas were shown by US but not CT. Four anaplastic tumors (19%) exhibited echogenicity extending beyond the enhanced area. In 4 patients an enhanced lesion contained a lucent center which proved to be echogenic. Low-grade astrocytomas were relatively homogeneous on US, while anaplastic astrocytomas were more inhomogeneous. Cysts could be found in both types of astrocytomas and were often small and multiple. The echo pattern was not helpful in differentiating metastases from primary tumors, although all of them had sharp margins. Sonography of the central nervous system can provide valuable information about tumor morphology an...
Intracranial Pressure and Neuromonitoring in Brain Injury, 1998
The present study was designed to validate our noninvasive ultrasonic technique (pulse phase lock... more The present study was designed to validate our noninvasive ultrasonic technique (pulse phase locked loop: PPLL) for measuring intracranial pressure (ICP) waveforms. The technique is based upon detecting skull movements which are known to occur in conjunction with altered intracranial pressure. In bench model studies, PPLL output was highly correlated with changes in the distance between a transducer and a reflecting target (R2 = 0.977). In cadaver studies, transcranial distance was measured while pulsations of ICP (amplitudes of zero to 10 mmHg) were generated by rhythmic injections of saline. Frequency analyses (fast Fourier transformation) clearly demonstrate the correspondence between the PPLL output and ICP pulse cycles. Although theoretically there is a slight possibility that changes in the PPLL output are caused by changes in the ultrasonic velocity of brain tissue, the decreased amplitudes of the PPLL output as the external compression of the head was increased indicates that the PPLL output represents substantial skull movement associated with altered ICP. In conclusion, the ultrasound device has sufficient sensitivity to detect transcranial pulsations which occur in association with the cardiac cycle. Our technique makes it possible to analyze ICP waveforms noninvasively and will be helpful for understanding intracranial compliance and cerebrovascular circulation.
The authors present a novel case of skeletal dysplasia in a 2.8-year-old girl. The patient presen... more The authors present a novel case of skeletal dysplasia in a 2.8-year-old girl. The patient presented with progressive lower cranial nerve palsy and myelopathy due to constriction at the cervicomedullary junction caused by overgrowth of the occipital bone of the foramen magnum and the C-1. She also had prominent bone overgrowth of the superior orbital ridges, resulting in excessive stretching of periorbital skin and an inability to fully close her eyes.
Neuromodulation: Technology at the Neural Interface, 2014
Data regarding rehospitalization and emergency department (ED) visits following vagus nerve stimu... more Data regarding rehospitalization and emergency department (ED) visits following vagus nerve stimulation (VNS) present data analysis challenges. We present a method that uses California's multiple databases to more completely assay VNS efficacy. The Healthcare Cost and Utilization Project's California Inpatient and Ambulatory Surgery databases were assayed for all VNS surgeries from 2005 to 2009. Patients were selected by epilepsy diagnosis codes and VNS procedure codes. Patients (total N = 629) were tracked across multiple databases using unique identifiers. Thirty-day and one-year post-implantation rates of VNS complication and healthcare visits were abstracted, along with one-year preoperative hospital and ED use. Statistics included correction for multiple comparisons. The one-year reoperation rate for adult patients (N = 536) was 3.9%; during the second year, an additional 3.2% of patients had reoperations. Within the first 30 days, <2% of patients experienced a complication. Four percent of patients were readmitted to a hospital, and 11.6% of patients visited an ED. The most common reason for rehospitalization or ED visit was seizure. In the first year after VNS, total seizure-related visits (hospitalization and ED) were 17% lower (2.12 visits per year to 1.71; p = 0.03). In the second year following VNS, seizure-related visits were 42% lower (2.21 visits per year to 1.27, p = 0.01). Pediatric patients (N = 93) had comparable results. VNS surgery has low rates of complications and reoperations and is associated with reduced incidence of seizure-related ED visits and hospital admissions in the first and second postoperative years.
... DM Campbell · S. Bruins, MD · CAC Wijman, MD, PhD (И) Stanford Stroke Center 701 Welch Road B... more ... DM Campbell · S. Bruins, MD · CAC Wijman, MD, PhD (И) Stanford Stroke Center 701 Welch Road Building B, Suite 325 Palo Alto, CA 94304, USA Tel.: +1 ... N Engl J Med 342:240-245 5. Roosen N, Martin JJ, de la Porte C, Van Vyve M (1985) Intracerebral hemor-rhage due to ...
Coccidioidal meningitis is a devastating complication of disseminated coccidioidomycosis. An anim... more Coccidioidal meningitis is a devastating complication of disseminated coccidioidomycosis. An animal model of this infection could enhance understanding of the pathogenesis of the disease and lead to improvements in therapy. A rabbit model of central nervous system infection simulating human disease was established using a blind cisternal tap technique to inoculate 4 1 10 3 -1 1 10 6 arthroconidia of Coccidioides immitis into the cisterna magna. Systemic, neurologic, and histopathologic findings of meningitis were observed in all rabbits, but an inoculum of 2 1 10 4 arthroconidia produced a chronic illness in which meningeal endarteritis obliterans was consistently observed. Serial sampling of cerebrospinal fluid demonstrated an inflammatory response. Growth of C. immitis was demonstrated by quantitative fungal culture from brains and proximal spinal cords.
Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravi... more Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravity. Previous flight observations document significant facial edema during exposure to microgravity, which suggests that ICP is elevated during microgravity. However, there are no experimental results obtained during space flight, primarily due to the invasiveness of currently available techniques. We have developed and refined a noninvasive technique to measure intracranial pressure noninvasively. The technique is based upon detecting skull movements of a few micrometers in association with altered intracranial pressure. We reported that the PPLL technique has enough sensitivity to detect changes in cranial distance associated with the pulsation of ICP in cadavera. In normal operations, however, we place a transducer on the scalp. Thus, we cannot rule out the possibility that the PPLL technique picks up cutaneous pulsation. The purpose of the present study was therefore to show that the PPLL technique has enough sensitivity to detect changes in cranial distance associated with cardiac cycles in vivo.
OBJECT Demonstrating the value of spine care requires adequate outcomes assessment. Long-term out... more OBJECT Demonstrating the value of spine care requires adequate outcomes assessment. Long-term outcomes are best measured as overall improvement in quality of life (QOL) after surgical intervention. Present registries often require parallel data entry, introducing inefficiencies and limiting compliance. The authors detail the methodology of constructing an integrated electronic health record (EHR) system to collect QOL metrics and demonstrate the effect of data collection on routine clinical workflow. A streamlined approach to collecting QOL data can capture patient data without requiring dual data entry and without increasing clinic visit times. METHODS Through extensive literature review, a combination of QOL assessments was selected, consisting of the Patient Health Questionnaire-2 and -9, Oswestry Disability Index, Neck Disability Index, and visual analog scale for pain. These metrics were used to provide assessment of QOL following spine surgery and were incorporated into standard clinic workflow by a multidisciplinary team of surgeons, advanced practice providers, and health care information technology specialists. A clinical dashboard tracking more than 25 patient variables was developed. Clinic flow was assessed and opportunities for improvement reviewed. Duration of clinic visits before and after initiation of QOL measure capture was recorded, with assessment of mean clinic visit times for the 12 months before and the 12 months after implementation. RESULTS The integrated QOL capture was instituted for 3 spine surgeons in a tertiary care academic center. In the 12-month period prior to initiating collection of QOL data, 806 new patient visits were completed with an average visit time of 127.9 ± 51.5 minutes. In the 12 months after implementation, 1013 new patient visits were recorded, with 791 providing QOL measures with an average visit time of 117.0 ± 45.7 minutes. Initially the primary means of collecting patient outcome data was via paper form, with gradual transition to collection via entry into the electronic medical records system. To improve electronic data capture, paper forms were eliminated and an online portal used as part of the patient rooming process. This improved electronic capture to nearly 98% without decreasing the number of patients enrolled in the process. CONCLUSIONS A systematic approach to collecting spine-related QOL data within an EHR system is feasible and offers distinct advantages over registries that require dual data entry. The process of data collection does not impact…
Hyperglycemia has been reported to worsen the tolerance of the brain to ischemia, and it has ther... more Hyperglycemia has been reported to worsen the tolerance of the brain to ischemia, and it has therefore been recommended that patients undergoing neurosurgical procedures not receive glucose-containing solutions. However, whereas most animal studies have used global ischemia models, most neurosurgical procedures are associated with risks of focal rather than global ischemia. We therefore studied the effects of glucose administration in an animal model of focal cerebral ischemia. We anesthetized 20 cats with halothane (0.85% end tidal in oxygen), and a focal cerebral ischemic lesion was produced by clip ligation of the left middle cerebral artery using a transorbital approach. Hyperglycemia (10 cats, mean +/- SEM plasma glucose concentration 561 +/- 36 mg/dl) was established before ligation by infusion of 50% glucose in 0.45% saline; the control group (10 cats, mean +/- SEM plasma glucose concentration 209 +/- 28 mg/dl) received 0.45% saline only. Total fluid administered, mean arteri...
This study was designed to investigate effects of whole body tilting on intracranial compliance a... more This study was designed to investigate effects of whole body tilting on intracranial compliance and pressure in six healthy volunteers by using a noninvasive ultrasonic device. Subjects were randomly tilted up or down sequentially at 60 degree, 30 degree head-up, supine, and 15 degree head-down position for one minute at each angle. We measured arterial blood pressure with a finger pressure cuff and changes in intracranial distance with an ultrasonic device. The device measures skull movement on the order of micro-meter. Our ultrasound technique demonstrates that skull movement is highly correlated (r$(circumflex){2}$=0.77) with intracranial pressure variations due to cerebral arterial pulsation. The amplitudes of arterial pressure (r$(circumflex){2}$=0.99 and those of intracranial distance changes (r$(circumflex){2}$=0.87) associated with one cardiac cycle were inversely correlated with the angle of tilt. The ratio of pulsation amplitudes for intracranial distance over arterial pre...
Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravi... more Intracranial pressure (ICP) dynamics are important for understanding adjustments to altered gravity. ICP may increase during microgravity due to a fluid shift to the head. As widely observed in clinical settings, elevated ICP causes headache, nausea, and projectile vomiting, which are similar to symptoms of the space adaptation syndrome. At levels over 20 millimeters mercury, ICP may compromise cerebral circulation. However, there are no experimental results to support the hypothesis that ICP is actually altered during microgravity exposure, primarily because o i the invasiveness of currently available techniques. Ames has developed and refined an ultrasonic device that measures changes in intracranial distance noninvasively using a patented pulse phase locked loop (PPLL) technique. Although the skull is assumed to be rigid, many investigators report that the skull moves on the order of micrometers in association with ICP pulsation resulting from variations in arterial pressure. The...
TiTlE ModEl SuMMAry PrESEnTEd Comparative healing of surgical incisions created by standard elect... more TiTlE ModEl SuMMAry PrESEnTEd Comparative healing of surgical incisions created by standard electrosurgery, PEAK PlasmaBlade, and standard scalpel blade
Proceedings of the National Academy of Sciences, 2015
The human brain is a tissue of vast complexity in terms of the cell types it comprises. Conventio... more The human brain is a tissue of vast complexity in terms of the cell types it comprises. Conventional approaches to classifying cell types in the human brain at single cell resolution have been limited to exploring relatively few markers and therefore have provided a limited molecular characterization of any given cell type. We used single cell RNA sequencing on 466 cells to capture the cellular complexity of the adult and fetal human brain at a whole transcriptome level. Healthy adult temporal lobe tissue was obtained during surgical procedures where otherwise normal tissue was removed to gain access to deeper hippocampal pathology in patients with medical refractory seizures. We were able to classify individual cells into all of the major neuronal, glial, and vascular cell types in the brain. We were able to divide neurons into individual communities and show that these communities preserve the categorization of interneuron subtypes that is typically observed with the use of classic interneuron markers. We then used single cell RNA sequencing on fetal human cortical neurons to identify genes that are differentially expressed between fetal and adult neurons and those genes that display an expression gradient that reflects the transition between replicating and quiescent fetal neuronal populations. Finally, we observed the expression of major histocompatibility complex type I genes in a subset of adult neurons, but not fetal neurons. The work presented here demonstrates the applicability of single cell RNA sequencing on the study of the adult human brain and constitutes a first step toward a comprehensive cellular atlas of the human brain.
Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology, 1998
It is believed that intracranial pressure (ICP) may be elevated in microgravity because a fluid s... more It is believed that intracranial pressure (ICP) may be elevated in microgravity because a fluid shift toward the head occurs due to loss of gravitational blood pressures. Elevated ICP may contribute to space adaptation syndrome, because as widely observed in clinical settings, elevated ICP causes headache, nausea, and projectile vomiting, which are similar to symptoms of space adaptation syndrome. However, the hypothesis that ICP is altered in microgravity is difficult to test because of the invasiveness of currently-available techniques. We have developed a new ultrasonic technique, which allows us to record ICP waveforms noninvasively. The present study was designed to understand postural effects on ICP and assess the feasibility of our new device in future flight experiments.
Idiopathic granulomatous inflammation of the pituitary gland occurs rarely, and is usually identi... more Idiopathic granulomatous inflammation of the pituitary gland occurs rarely, and is usually identified as an incidental finding at autopsy. However, it may present during life as a mass lesion that clinically mimics other more common pituitary gland lesions. We report a 54-year-old woman presenting with acute onset diabetes insipidus whose MRI showed a 1.1 cm pituitary mass, with infundibular thickening and meningeal enhancement. Biopsy demonstrated granulomatous hypophysitis with multinucleate histiocytes. Special studies for infectious organisms were negative. The patient's disease progressed following biopsy, causing complete loss of vision in the right eye. This responded to high-dose steroids and local lowdose radiation. She later developed an acute inferior myocardial infarction. Laboratory tests failed to demonstrate an underlying autoimmune process. While recovering from this myocardial infarction, she succumbed to pulmonary embolism. Autopsy revealed moderate residual ch...
We report two cases of central neurocytoma; one located in the right lateral ventricle and associ... more We report two cases of central neurocytoma; one located in the right lateral ventricle and associated with a distinctly separate primitive neuroectodermal tumor (PNET)/medulloblastoma of the fourth ventricle, and the other admixed with fat cells and arising from the left lateral and third ventricles with extension into the corpus callosum. We discuss that concurrent occurrences of PNET and adipose tissue are not fortuitous events, but an evidence that neurocytomas and PNETs originate in the residual germinal pool from common progenitor cell rests recapitulating features of developing neurons and with a potential for mesenchymal differentiation.
Intraoperative ultrasound (US) was compared to computed tomography (CT) in 41 intracranial and 6 ... more Intraoperative ultrasound (US) was compared to computed tomography (CT) in 41 intracranial and 6 spinal cord tumors. The studies correlated closely except for primary gliomas. Eight of the 22 primary intracranial gliomas (37%), including 1 low-grade and 7 anaplastic tumors, were larger and more extensive on US than on CT. Margins of non-enhanced primary astrocytomas were shown by US but not CT. Four anaplastic tumors (19%) exhibited echogenicity extending beyond the enhanced area. In 4 patients an enhanced lesion contained a lucent center which proved to be echogenic. Low-grade astrocytomas were relatively homogeneous on US, while anaplastic astrocytomas were more inhomogeneous. Cysts could be found in both types of astrocytomas and were often small and multiple. The echo pattern was not helpful in differentiating metastases from primary tumors, although all of them had sharp margins. Sonography of the central nervous system can provide valuable information about tumor morphology an...
Intracranial Pressure and Neuromonitoring in Brain Injury, 1998
The present study was designed to validate our noninvasive ultrasonic technique (pulse phase lock... more The present study was designed to validate our noninvasive ultrasonic technique (pulse phase locked loop: PPLL) for measuring intracranial pressure (ICP) waveforms. The technique is based upon detecting skull movements which are known to occur in conjunction with altered intracranial pressure. In bench model studies, PPLL output was highly correlated with changes in the distance between a transducer and a reflecting target (R2 = 0.977). In cadaver studies, transcranial distance was measured while pulsations of ICP (amplitudes of zero to 10 mmHg) were generated by rhythmic injections of saline. Frequency analyses (fast Fourier transformation) clearly demonstrate the correspondence between the PPLL output and ICP pulse cycles. Although theoretically there is a slight possibility that changes in the PPLL output are caused by changes in the ultrasonic velocity of brain tissue, the decreased amplitudes of the PPLL output as the external compression of the head was increased indicates that the PPLL output represents substantial skull movement associated with altered ICP. In conclusion, the ultrasound device has sufficient sensitivity to detect transcranial pulsations which occur in association with the cardiac cycle. Our technique makes it possible to analyze ICP waveforms noninvasively and will be helpful for understanding intracranial compliance and cerebrovascular circulation.
The authors present a novel case of skeletal dysplasia in a 2.8-year-old girl. The patient presen... more The authors present a novel case of skeletal dysplasia in a 2.8-year-old girl. The patient presented with progressive lower cranial nerve palsy and myelopathy due to constriction at the cervicomedullary junction caused by overgrowth of the occipital bone of the foramen magnum and the C-1. She also had prominent bone overgrowth of the superior orbital ridges, resulting in excessive stretching of periorbital skin and an inability to fully close her eyes.
Neuromodulation: Technology at the Neural Interface, 2014
Data regarding rehospitalization and emergency department (ED) visits following vagus nerve stimu... more Data regarding rehospitalization and emergency department (ED) visits following vagus nerve stimulation (VNS) present data analysis challenges. We present a method that uses California's multiple databases to more completely assay VNS efficacy. The Healthcare Cost and Utilization Project's California Inpatient and Ambulatory Surgery databases were assayed for all VNS surgeries from 2005 to 2009. Patients were selected by epilepsy diagnosis codes and VNS procedure codes. Patients (total N = 629) were tracked across multiple databases using unique identifiers. Thirty-day and one-year post-implantation rates of VNS complication and healthcare visits were abstracted, along with one-year preoperative hospital and ED use. Statistics included correction for multiple comparisons. The one-year reoperation rate for adult patients (N = 536) was 3.9%; during the second year, an additional 3.2% of patients had reoperations. Within the first 30 days, <2% of patients experienced a complication. Four percent of patients were readmitted to a hospital, and 11.6% of patients visited an ED. The most common reason for rehospitalization or ED visit was seizure. In the first year after VNS, total seizure-related visits (hospitalization and ED) were 17% lower (2.12 visits per year to 1.71; p = 0.03). In the second year following VNS, seizure-related visits were 42% lower (2.21 visits per year to 1.27, p = 0.01). Pediatric patients (N = 93) had comparable results. VNS surgery has low rates of complications and reoperations and is associated with reduced incidence of seizure-related ED visits and hospital admissions in the first and second postoperative years.
... DM Campbell · S. Bruins, MD · CAC Wijman, MD, PhD (И) Stanford Stroke Center 701 Welch Road B... more ... DM Campbell · S. Bruins, MD · CAC Wijman, MD, PhD (И) Stanford Stroke Center 701 Welch Road Building B, Suite 325 Palo Alto, CA 94304, USA Tel.: +1 ... N Engl J Med 342:240-245 5. Roosen N, Martin JJ, de la Porte C, Van Vyve M (1985) Intracerebral hemor-rhage due to ...
Coccidioidal meningitis is a devastating complication of disseminated coccidioidomycosis. An anim... more Coccidioidal meningitis is a devastating complication of disseminated coccidioidomycosis. An animal model of this infection could enhance understanding of the pathogenesis of the disease and lead to improvements in therapy. A rabbit model of central nervous system infection simulating human disease was established using a blind cisternal tap technique to inoculate 4 1 10 3 -1 1 10 6 arthroconidia of Coccidioides immitis into the cisterna magna. Systemic, neurologic, and histopathologic findings of meningitis were observed in all rabbits, but an inoculum of 2 1 10 4 arthroconidia produced a chronic illness in which meningeal endarteritis obliterans was consistently observed. Serial sampling of cerebrospinal fluid demonstrated an inflammatory response. Growth of C. immitis was demonstrated by quantitative fungal culture from brains and proximal spinal cords.
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Papers by Lawrence Shuer