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Biomedical subjects

W M Chadduck

Publications and source records attributed to W M Chadduck.

At least 55 records · Page 3Linked to original sources
PubMed1989

Duplex pulsed Doppler US versus intracranial pressure in the neonate: clinical and experimental studies.

This study was conducted to determine if the resistive index (RI) could be used for the examination and follow-up of neonates with increased intracranial pressure. First, in a laboratory model with four mongrel dogs, RI was found to correlate linearly with cerebral perfusion pressure. Second, RI was studied in 57 healthy neonates and 285 neonates with abnormal clinical or head ultrasound findings. Average RI for healthy newborns was 75 +/- 10 and was inversely related to gestational age. RI in newborns with abnormal findings was uniformly elevated, but these values varied considerably and were not statistically different from normal values. Third, the RI was found to decrease significantly after patent ductus arteriosus ligation, tapping of subdural effusions, ventricular tapping (later cerebrospinal fluid shunting led to a further drop in RI), and ventriculoperitoneal shunting. Elevated RI indicates possible intra- or extracranial abnormality affecting cerebral blood flow. Doppler RI is valuable in following up neonates with abnormal or unstable conditions and in assessing the effectiveness of therapies to improve cerebral perfusion.

Animals↗
PubMed1989

Brain death in infants: evaluation with Doppler US.

In a preliminary study, nine infants with a clinically determined diagnosis of brain death were examined with duplex pulsed Doppler ultrasonography (US) through the anterior fontanelle. Flow velocity measurements were made in the intracranial internal carotid artery and anterior cerebral artery. Resistive index (RI) was calculated in each patient and used as an indicator of diastolic flow. Eight of nine infants showed markedly elevated RI (100%-191%) with reversal of diastolic flow. One infant had low RI (42%-58%) with preserved systolic and diastolic flow until death. The authors believe that the elevation of RI with diastolic flow reversal seen in these patients is a reflection of increased intracranial pressure and is a sign of poor prognosis when present on serial examinations. Cranial duplex pulsed Doppler US is a useful, noninvasive tool in the diagnosis of brain death in infants but must be carefully correlated with clinical examination and other diagnostic tests.

Blood Flow Velocity↗
PubMed1989

Intracranial duplex Doppler: practical uses in pediatric neurology and neurosurgery.

The value of pulsed Doppler studies of the cerebral vessels of neonates, infants, and children having neurologic and neurosurgical problems is presented. In this study, Resistive Index--[(peak systolic velocity - end-diastolic velocity)/peak systolic velocity] x 100--was used in correlative studies of pediatric patients having hydrocephalus, extra-axial collections, shunt malfunctions, vascular malformations, and craniocerebral injuries. Age-related normal values for Resistive Index are defined, with special attention to the expected values in patients having normally functioning ventriculoperitoneal shunts. Correlations of Resistive Index with intracranial pressure in animal models, as well as a variety of pathologic pediatric neurosurgical conditions, emphasize the usefulness of pulsed Doppler studies in some conditions as well as limitations in others.

Adolescent↗
PubMed1989

Perioperative sonography.

Experience using intraoperative real-time sonographic examinations for over a thousand patients has delineated the advantages of this surgical adjunct for a number of cranial and spinal pediatric neurosurgical procedures. Unusual and unfamiliar angles of insonation call for careful attention to anatomy. The advantages of intraoperative sonography in localizing intracerebral tumors, brain abscesses, and foreign bodies are demonstrated. In addition, adequacy of tumor removal can be assessed better at the time of operation and the operative area can be inspected for bleeding even after dural closure. In the pediatric age group, intraoperative real-time sonography is used most commonly for placement of shunts, allowing positioning of the ventricular catheter tip away from the choroid plexus. The use of air as a contrast agent in conjunction with intraoperative sonography allows better identification of catheter tips and can demonstrate the intercommunication of potentially isolated cavities within the brain. Intraoperative sonography has been extremely helpful, especially for identifying cysts within and the extent of intramedullary spinal cord tumors. Visualization of a syrinx is exquisite. Some of the cases presented also serve to identify limitations of intraoperative sonography as a surgical adjunct.

Brain Diseases↗
PubMed1988

Experience with simultaneous ventriculo-peritoneal shunt placement and myelomeningocele repair.

A program evaluating simultaneous shunt placement and neural tube repair is described and compared with a concomitant series of patients whose surgeons preferred delayed shunting. Twenty-two patients had simultaneous closure of neural tube defects and placement of ventriculoperitoneal shunts; one was shunted 1 day prior to closure of a leaking myelomeningocele. Eleven other patients had closure of myelomeningoceles followed by shunting 6 to 14 days later. Four patients have not required shunting. Three patients needed complex flap rotations and silastic dural closures, but the complexity of the myelomeningocele closure was not a criterion for excluding simultaneous shunting. The only criteria were preference of the attending surgeon, and ventricular size. All but one in the simultaneous shunting (SS) group had moderate to marked hydrocephalus at birth; one initially selected not to have a shunt, but within 24 hours had marked increase in ventricular size by ultrasonography performed when the child was anesthetized for the myelomeningocele closure. In the SS group, surgical innovations included (1) use of the semilateral position for exposure of both operative sites for shunting and the myelomeningocele closure, (2) posteriorly-placed subcutaneous peritoneal catheter, and (3) a combined surgical approach using two surgeons and separate instrumentation. There was no operative mortality in either group; there were no infections within 30 days in either group. There was one infection at 5 months in the SS group, and one at 2 months in the delayed shunting (DS) group; the long-term infection rate was 5%, comparable to any published series.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal Fluid Shunts↗
PubMed1987

Gliosarcoma with chromosome abnormalities in a neonate exposed to heptachlor.

A neonate with a cerebral gliosarcoma was found to have chromosome abnormalities in tissue culture of the tumor, but normal karyotyping of peripheral blood. Similarities to and differences from chromosome abnormalities found in other human gliomas are noted. Unusual exposure of the child to heptachlor during prenatal development and the neonatal period suggests the need for further studies on the role of toxins in oncogenesis.

Animals↗
PubMed1987

MR imaging of spinal epidural sepsis.

Four patients with spinal epidural sepsis were evaluated with MR imaging. The lesions were best visualized with spin-echo techniques with long repetition (2000 msec) and long echo (80-100 msec) times. Sagittal and axial images were equally important in defining the extent of the lesions. Comparison with available contrast-enhanced CT scans showed that MR was more definitive in the early demonstration of the abscesses. This early recognition influenced the management greatly and improved the clinical outcome significantly. The findings in our four cases support previous reports that MR is superior to other imaging methods for early recognition and anatomic localization of infectious diseases in patients suspected of having either spinal osteomyelitis or spinal epidural sepsis.

Adult↗
PubMed1986

Paraplegia caused by coarctation of the aorta and hydrocephalus.

A patient with untreated coarctation of the aorta, as well as shunt-dependent hydrocephalus, developed paraplegia when shunt malfunction resulted in a cerebrospinal fluid pressure greater than 560 mm water. Improvement followed shunt revision. The unique combination of mechanisms involved in the decreased spinal cord perfusion pressure is discussed.

Aortic Coarctation↗
PubMed1986

Diagnosis of diastematomyelia with high-resolution spinal ultrasound.

Two children with diastematomyelia were diagnosed before operation with high-resolution spinal ultrasonography. Neonates with evident or suspected diastematomyelia can be effectively examined by high-resolution spinal ultrasonography and spinal radiography, reserving more invasive techniques for those for whom the method proves inadequate.

Child, Preschool↗
PubMed1985

Intraventricular cavernous hemangioma: report of three cases and review of the literature.

The clinical and radiographic presentations of 3 patients with intraventricular cavernous hemangioma are described. The accumulated total of 19 cases from the literature are compared to determine whether there is a common clinical and radiographic presentation for this benign intraventricular lesion. The differential diagnosis of intraventricular cavernous hemangioma includes intraventricular meningioma, choroid plexus papilloma, arteriovenous malformation, low grade astrocytoma, and ependymoma.

Adult↗
PubMed1985

Intraoperative ultrasound for spinal lesions.

A variety of spinal pathological processes demonstrated by intraoperative ultrasound is presented. Use of spinal ultrasound proved helpful in viewing alignment, assessing spinal cord pathology, and viewing anterior to the cord in cases of spinal trauma. As an operative adjunct, ultrasound was especially helpful for viewing extradural spinal metastases and cavitary lesions of the spinal cord, such as syrinxes, cystic tumors, and hematomas. In cases of spondylotic myelopathy, intraoperative ultrasound allowed assessment of the adequacy of the decompression, the space ventral to the cord, and the size and configuration of the spinal cord.

Cervical Vertebrae↗
PubMed1984

Squamous cell carcinoma and meningomyelocele.

A case of invasive squamous cell carcinoma arising in the skin overlying a large lumbar meningomyelocele is reported. This case is unique in that a chronic neurocutaneous fistula was not present. It is proposed that chronic irritation of the meningomyelocele was the primary factor in the pathogenesis of the cancer.

Adult↗
PubMed1984

Septic complications of chemonucleolysis.

The authors present two cases of septic complications after chemonucleolysis with chymopapain. One patient developed overt aortic valve failure. The second patient suffered an epidural abscess.

Adult↗