Biomedical subjects
Publications and source records attributed to D J Gower.
Diastematomyelia is a rare but potentially devastating spinal dysraphism classically characterized as a bony or fibrous spur separating two hemispinal cords. This study reviews our experience with diastematomyelia over a 40-year period from 1947 through 1987, and suggests that the neurologic and orthopedic deficits of diastematomyelia remain stable during extended follow-up after surgery.
There is general agreement that aggressive management and monitoring of the patient with closed head injury with control of intracranial pressure (ICP) will improve patient survival and eventual outcome. Conversely, there is little agreement on the value of surgical craniectomy for increasing intracranial volume and subsequently decreasing ICP in these same patients. This study examines 115 patients with severe closed head injuries (Glasgow Coma Score 8 or less) seen at the North Carolina Baptist Hospital between July 1, 1983, and April 1, 1987. All 115 patients were started on a regimen of head elevation, fluid restriction, chemoparalysis, and hyperventilation at PCO2 25-30 torr. Fifty-seven patients failed to respond to that therapy and were given mannitol. Twenty-seven of these still failed to respond; 24 were placed in a pentobarbital coma therapy group and 3 underwent subtemporal decompression. Of the 24 patients in pentobarbital coma, 17 failed to respond, 7 of whom underwent subtemporal decompression and 10 of whom were not operated on. Of all 10 patients undergoing subtemporal decompression, 7 (70%) responded with an average reduction in ICP of 34% (+/- 19.5% SD). Of the 10, 4 died (40%), in contrast with a mortality of 82.4% among patients in pentobarbital coma without subtemporal decompression. These data strongly suggest that subtemporal decompression can be beneficial in patients with medically intractable elevations of ICP.
A young patient with the posttraumatic development of a superficial temporal artery (STA) aneurysm is described. The STA was ligated proximal and distal to the aneurysm, and the aneurysm was removed. The diagnosis and treatment of traumatic STA aneurysms are discussed.
Anterior sacral meningoceles are rare. This report describes familial anterior sacral meningoceles in a father and daughter who underwent magnetic resonance imaging as part of the preoperative evaluation. Magnetic resonance imaging showed a pelvic teratoma in the daughter and confirmed the absence of abnormal tissue in the father--findings not clearly provided by ultrasound studies, myelography, or contrast-enhanced computerized tomography. It is believed that MR imaging is the most useful preoperative diagnostic technique available in establishing a treatment plan for anterior sacral meningocele.
Due to its investiture with bone, the spinal cord can be difficult to study anatomically and histologically. Tissue degradation during immersion fixation or mechanical trauma during extraction of unfixed tissue often produces confusing artifacts. Perfusion fixation eliminates many of these problems, but it is a slow, tedious, and technically demanding procedure. This report demonstrates that microwave irradiation of the spinal cord before its removal from the spine is a rapid and easy method of tissue fixation with an absence of artifacts comparable to that with perfusion fixation.
Clathrin, the main constituent of coated vesicles, is anterogradely transported exclusively in the slow component b (SCb) of axonal transport. However, it has not been shown whether the 30-36-kDa clathrin-associated proteins (CAPs), which may regulate assembly of clathrin into coated vesicles, are transported along with clathrin in SCb. Clarification of this point has implications for the functional state of anterogradely transported clathrin. To investigate CAPs transport, retinal ganglion cells of the guinea pig were labeled with 35S-methionine and the optic nerves harvested at 6 h, 4 days, and 30 days to collect radiolabeled proteins from each major rate component of axonal fast component (FC), slow component a (SCa), and SCb. The radiolabeled rate component proteins were analyzed by using two-dimensional polyacrylamide gel electrophoresis and fluorography. The results showed that CAPs, like clathrin, were transported exclusively with the proteins of SCb. In addition, a comparison of radiolabeled CAPs isolated from axons with whole-brain CAPs failed to demonstrate an appreciable difference in molecular weight or isoelectric point between the two, suggesting that CAPs did not undergo a major post translational modification upon passage into the synaptic terminal. It appears that the distinctive microenvironment within the synaptic terminal is likely to contribute to the ability of clathrin and CAPs to interact with membranes.
Penetration into the abdominal cavity with injury to visceral, vascular, or neural structures is a potentially life-threatening complication of lumbar disc exploration. In this report, we used reconstructed computed tomographic measurements of the L3-L4, L4-L5, and L5-S1 intervertebral discs to show that lateral spine roentgenograms contain an unavoidable magnification error that makes accurate measurement of minimal depth to penetration impossible. This magnification error may mislead the unwary surgeon into an overestimation of actual disc size. Moreover, the "safe distances" that have been published for the avoidance of penetration at the L3-L4, L4-L5, and L5-S1 intervertebral levels would have been excessive for 22.2%, 19.4%, and 8.3%, respectively, of the 26 patients in our study.
Papilloedema is not always an adequate predictor of potential complications from lumbar puncture, and many clinicians are using computed tomography (CT) before lumbar puncture in an effort to identify more accurately the "at risk" patient. This paper identifies the following anatomical criteria defined by CT scanning that correlate with unequal pressures between intracranial compartments and predispose a patient to herniation following decompression of the spinal compartment: lateral shift of midline structures, loss of the suprachiasmatic and basilar cisterns, obliteration of the fourth ventricle, or obliteration of the superior cerebellar and quadrigeminal plate cisterns with sparing of the ambient cisterns. These criteria should be considered to be contraindications to lumbar puncture.
Ten fresh carotid plaques obtained from patients undergoing carotid endarterectomy were fixed, and their luminal surfaces were examined with a scanning electron microscope. Luminal surface defects, characterized in scanning electron microscopy as endothelial discontinuities having diameters of 50 to 1500 microns, were a frequent finding, but their presence did not correlate well with the location of ulcers seen on angiography. Potential sources of emboli found were peels of subendothelial matrix, fibrin-platelet aggregates, fibrin-red blood cell clusters, and, possibly, damaged endothelial cells. Areas of endothelial cell injury consisting of small denuded patches, sheets of endothelial cytoplasm, and distorted endothelial cell profiles were observed. These areas resembled the type of damage seen in experimental ischemic vessel lesions and were believed to be the result of carotid cross clamping. Their presence suggests that a similar mechanism may result in loss of endothelial cells and exposure of the "raw" plaque surface in vivo.
A recently formulated structural theory of axonal transport suggests that each group of transported material is a distinct class of functionally related structures and that the proteins making up those structures, with few exceptions, are found in only one rate component, thus maintaining a close noncovalent association during transport. If such a relationship exists, one would postulate that the labelled proteins at the leading edge and trailing edge of a rate component following a pulse of radioactive amino acid would be present in similar proportions. After retinal ganglion cell proteins were labelled by intraocular injection of radioactive amino acid in the guinea pig eye, the optic nerve and tract were analyzed at several post-injection intervals. The data thus derived support the existence of a close relationship among the "soluble" proteins of slow component b and are consistent with the structural concept of axonal transport. If diffusion were the mechanism of transport, the larger proteins would be expected to move slower than the smaller proteins. Such insights into the process of axonal transport should help to identify the variables critical to survival of neurons following acute trauma and degenerative diseases.
From 1976 through 1984, the period covered in this report, we reviewed our total experience with gram-negative meningitis in adult patients, looking especially at how treatment and mortality had changed. Thirty-nine adults had 45 episodes of gram-negative meningitis. Twenty-five patients had had a dura-arachnoid disruption, 12 a septic episode, and two a bacterial mastoiditis. The overall mortality was 35.9%. Thirteen patients were treated with a full course of intrathecal antibiotics (five or more days) and eight patients with an abbreviated course (one or two doses). The use of chloramphenicol was associated with poor patient outcome, a finding consistent with both experimental and clinical findings of others.
The rare cases of subgaleal hematoma in childhood reported previously have all been related to head trauma. A case of apparently spontaneous subgaleal hematoma is reported which was associated with a qualitative platelet defect and not with trauma. Subgaleal hematoma must be differentiated from subgaleal infection and air from frontal sinusitis with bony erosion, and from an encephalocele or tumor erosion through the skull. Computed cranial tomography is useful in that differentiation. Most cases have been managed conservatively, but subgaleal tap may be indicated if there is severe headache or potential scalp necrosis.
A soluble enzyme system that posttranslationally adds [3H]arginine to proteins in a ribosome-free preparation of guinea pig synaptoplasm is described. The reaction in synaptoplasm is inhibited by the addition of ribonuclease-A and puromycin, indicating tRNA dependence. A limited number of proteins in synaptoplasm (molecular weights of 20, 37, and 50 kilodaltons) were found to accept arginine. We suggest that RNA-dependent posttranslational amino acylation is used by the mammalian neuron for protein processing at the synaptic terminal.
Infection of cerebrospinal fluid shunts with Candida albicans is reported in two patients. Scanning electron microscopy in one case demonstrates the relationship of the Candida hyphae to the white blood cells and to silicone plastic. A review of 10 previously reported cases of Candida shunt infection indicates that the infection usually follows a major bacterial infection or direct contamination or occurs spontaneously. Previous therapy has usually involved removal of the shunt, and the role of parenteral antifungal therapy is still unclear. Overall mortality to date is 25%.
Biomaterials are essential for life support and monitoring of critically ill patients, but their use increases the risk of nosocomial infection. Of the various plastics used for life support and monitoring devices, polyvinylchloride is one to which bacteria most readily adhere. Through the use of qualitative culture techniques and scanning and transmission electron microscopy, we studied the surfaces of polyvinylchloride endotracheal tubes removed from 25 ICU patients, to determine if bacterial adhesion to those tubes was sufficient to provide a possible source for repeated contamination of the tracheobronchial tree. Of the surfaces studied, 16% were partially covered and 84% were completely covered by an amorphous bacteria-containing matrix. Some biofilm-enclosed bacterial aggregates projected from the matrix into the lumen of the tube. The mechanism by which endotracheal tubes repeatedly inoculate the lungs of intubated patients may prove to be dislodgment of such aggregates by suction apparatus.
Between the years 1963 to 1982, 84 consecutive cases of intracranial complications of ear disease in pediatric patients were diagnosed and treated at the North Carolina Baptist Hospital. This group consisted of 65 patients with otitic meningitis, four with otitic brain abscess, four with otitic hydrocephalus, three with lateral sinus thrombosis, three with otitic subdural empyemas, and five with an otitic subdural effusion of fluid. The advent of antibiotics has drastically altered the natural history of middle ear infections. We present these 84 cases to review diagnostic problems and therapeutic options, and to offer a plea for continued awareness of the middle ear as a potential source of central nervous system complications.
Home ventilator support, though somewhat unorthodox, is economically desirable and is now technically feasible. Close cooperation between public health providers, ventilator suppliers, and the family physician, as well as strong patient and family compliance, is essential for success in maintaining a ventilator-dependent patient at home.
Recently, a delayed hypersensitivity reaction to silicone plastics has been demonstrated in some patients with breast and joint implants and subcutaneously injected silicone. In this study, the authors examined the internal surface of shunting systems to evaluate the cellular response to implanted silicone plastic. The distal peritoneal tubing from 20 patients with ventriculoperitoneal shunts was examined with a scanning electron microscope. Twelve tubes were removed because of documented distal shunt malfunction and eight for an elective lengthening procedure. Cultures of all tubing were negative. The catheters removed for malfunction contained a variety of cells: sometimes in clumps, sometimes associated with platelets and densely adherent to the silicone tubing wall. In several shunts, giant cells were seen with multiple foot processes adherent to the internal silicone surface. The internal surface of the tubing of two malfunctioning shunts was embedded in electron microscopy plastic and studied with transmission electron microscopy. The cells proved to be neutrophils with no evidence of silicone granules inside the cell bodies. The shunts removed for elective revision showed only a few cells, and those were never associated with platelets. There was proteinaceous material scattered on the internal surface of the tubing, but the cellular response was markedly different from that in malfunctioning shunts. The authors postulate that the findings in malfunctioning shunt tubing represent a delayed hypersensitivity to silicone similar to that seen with other types of silicone implants.