Biomedical subjects
Publications and source records attributed to D J David.
A technique of rigid miniscrew fixation of cantilever nasal bone grafts is described. This produces stable, predictable nasal contour and tip projection without significant bone graft resorption.
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The classification by Tessier of rare craniofacial clefts brought, for the surgeon, order to a previously confusing array of anatomic and developmental descriptions. An ordered two-dimensional categorization of severe clefting malformations evolved from his clinical, radiologic, and surgical observations. The purpose of this paper is to report a complete series of facial clefts studied with computed tomography (CT) and three-dimensional reconstruction. The CT analysis supports some, but contradicts other, hypotheses and speculations presented by Tessier. The CT data reveal the scale of the reconstructive challenge and allow the assessment of our therapeutic interventions.
Observations after a fatal motorcycle accident suggested that the face bar of a full-face helmet may transmit an impacting force to the skull base via the chin strap and the mandibular rami and condyles, bypassing the energy-absorbing facial bones. If this mechanism is confirmed, the structural properties of these face bars will need to be reassessed.
After 10 years' work in the area of cleft palate, we decided to assess the acceptability of the speech of the children concerned. To ensure objectivity, untrained listeners, who were not aware that they were listening to children with repaired cleft palate, were asked to evaluate the child's spontaneous speech by comparing it with the speech of three of that child's peers. The results suggested that the child spoke less acceptably than his peers. As our aim was to compare the child with his peers, a rank ordering was selected as a means of evaluation rather than absolute judgements, i.e. a rating scale. The tape recordings of the cleft repaired children were also assessed by a speech pathologist experienced in the management of these children. The results of this assessment were comparable with results obtained overseas. In the light of our findings, we suggest that peer group comparison by untrained "naïve listeners may be a useful adjunct to the traditional assessment by the speech pathologist.
The review of a complete series of Tessier craniofacial cleft patients presenting to the South Australian Cranio-facial Unit has identified within the hairline a regular marker of clefting. Tongue-like projections of the temporal and frontal hairline pointing in the direction of their respective clefts have been identified for Tessier clefts numbered 7 to 14. No hairline indicator was revealed in "southbound" clefts numbered 0 to 6 without "northbound" extension. The hairline markers of laterally and superiorly bound clefts are a complementary element of the Tessier classification system.
Since 1978, 35 patients have undergone mandibular reconstruction with vascularized iliac crest. During this time, the technique of raising and shaping the iliac crest has undergone a series of modifications. Initially, osteocutaneous segments based first on the superficial circumflex iliac system and later on the deep circumflex iliac system were used. More recently, only the inner table of the ilium has been employed, and where intraoral lining is required, an ulnar forearm free flap has been added. Thirty-two patients were reconstructed successfully. Of the three anastomotic failures, one bony segment was able to survive as a free graft. There were no donor-site complications. With continued experience, operative morbidity has been minimized, while the technique has been modified to tailor the reconstruction to the specific requirements of the patient. It is concluded that vascularized iliac crest provides the most appropriate mandibular reconstruction for a range of congenital and acquired defects.
During the period July 1980-August 1987, 21 patients required cranio-facial extension of conventional neurosurgical osteotomies for tumours of the skull base and orbit. Five different types of combined osteotomies are described. Their applications to the treatment of various tumours and the subsequent reconstructions are presented and discussed.
Infection following transcranial surgery may be devastating. A review of 170 transcranial operations is presented with a focus on postoperative infection and its relationship to patient age, preoperative microbiology, pattern of operation, length of operation, and the use of antibiotic prophylaxis. The overall postoperative infection rate was 6.5 percent, but the infection rate in adults (23.5 percent) was much higher than in children (2.2 percent). Higher infection rates were found in adults with craniofacial dysostoses undergoing lengthy frontofacial advancements which required tracheostomy airway management. The residual frontal extradural dead space following advancement in adults is a sanctuary to infecting organisms from the respiratory tract--especially Pseudomonas transferred from the tracheostomy site into the upper airway and intracranial dead space by ventilation forces. Operating times for patients who became infected were 2 1/2 hours longer than average operating times for transcranial operations. Preoperative microbiology of the craniofacial region was not a good predictor of subsequent infection. Recommendations include operative intervention at an early age, short preoperative hospital stay, antibiotic prophylaxis to include gram-negative cover, surgical measures to either fill or isolate the dead space, and strict tracheostomy care--preferably with the patient being barrier-nursed.
Variability of deformities in hemifacial microsomia has precluded the general acceptance of any classification based on one reference organ. We present a review of hemifacial microsomia classifications and propose a TNM-style multisystem classification. This alphanumeric coding system, SAT, provides cohesion to existing hemifacial microsomia classifications. The acronym SAT is derived as follows: S = skeletal, A = auricle, and T = soft tissue. There are five levels of skeletal deformity (S1 through S5), four levels of auricular deformity (A0 through A3), and three levels of soft-tissue deformity (T1 through T3). Hence a patient with minimal deformity would be classified S1A0T1, whereas a patient with the most severe deformity would be S5A3T3.
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Frontoethmoidal meningoencephaloceles constitute a well-defined clinical entity with remarkable epidemiologic peculiarities, being very prevalent in Southeast and Southern Asia, but relatively rare in Western Europe, Japan, Australia, and North America. They do not show an increased risk of recurrence in siblings and offspring, unlike other cephaloceles and neural tube defects generally, from which they should be distinguished. Combined craniofacial and neurosurgical operative treatment permits one-stage correction of the whole deformity, the associated hypertelorism being reduced by selective orbital translocation and the nasal deformity by rhinoplasty. In planning these procedures, three-dimensional CT scanning is very helpful. Although our experience is chiefly with cases referred in childhood, we have some experience with operations done in infancy and believe this to be the ideal age.
Bacteremia occurs in 3 to 4 percent of ambulatory young children with fever. Bacteremic children may not appear seriously ill or have an identifiable source of infection, but they are at risk of developing septic complications if they are not treated appropriately. The physician must be aware of clinical criteria that identify children at increased risk for unsuspected bacteremia. Careful management leads to a relatively safe and successful outcome.
Twenty-five cases of fronto-ethmoidal meningoencephaloceles have been studied. The relationship to other sincipital meningoencephaloceles is explored. In all cases the exit holes from the anterior cranial fossa are at the site of the foramen caecum. The facial component of the defect determines the sub-classification: naso-frontal, naso-ethmoidal and naso-orbital. The cranio-facial deformity may consist of hypertelorism, orbital dystopia, elongation of the face and dental malocclusion. These reflect the distorting influence of the extruded intracranial contents on facial growth. Early removal of the meningoencephalocele by the cranio-facial route is recommended to allow normal growth forces to be re-established. In older patients with established deformities translocation of the orbits may be necessary.
The stability of 146S particles in concentrates of foot-and-mouth disease virus stored at 4 degrees C was similar to that of 146S particles in a conventional virus preparation. Proteolytic degradation of VPl was not observed in the stored conventional virus preparation or inhibitor-supplemented concentrate but was observed in a supplement-free concentrate. The potencies of vaccines made from the conventional and concentrated preparations and stored in parallel at 4 degrees C appeared to decrease after 16 weeks. The vaccines made from the supplement-free concentrate and the Trasylol supplemented concentrate appeared to be at least as potent as the conventional vaccine and were clearly superior to vaccine made from ox serum supplemented concentrate.
A series of 74 cephaloceles (17 cranial meningoceles and 57 meningoencephaloceles) is reported. Infants born with large meningoencephaloceles containing recognizable cerebral tissue usually did badly despite endeavors to conserve brain function by expanding the cranial capacity (5 cases) or decompressing hydrocephalic ventricles (9 cases). Infants with cranial meningoceles almost all did well, even when there was associated hydrocephalus. The etiological diversity of cephaloceles is emphasized. Frontoethmoidal meningoencephaloceles, which occur with noteworthy frequency in South and Southeast Asia, require separate consideration in both genetic counseling and treatment; the associated facial deformities (hypertelorism and orbital dystopia) can be corrected with a one-stage craniofacial reconstruction. Antenatal diagnosis by ultrasound is now often possible and was achieved in 4 cases; we suggest that neurosurgeons should participate in such antenatal evaluations.
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It is postulated that craniosynostosis is due to a growth abnormality in all or part of the cranial capsule. Release of the stenosed part in the first months of life will re-establish the balance between the rapidly growing brain and eye, and the cranial capsule. Three periods for operative treatment are described: early, intermediate and late. Only in the early period can operative treatment restore normal growth dynamics; in the late period the aim is correction of an established deformity. The relationship between cranial clefts and frontonasal encephaloceles is explored. If the space-occupying encephalocele is removed early, the distorted facial bones adopt a more normal position, whereas cranial clefts do not respond to early operation by remoulding. The treatment of the acquired deformities of acute cranio-facial trauma have taken on new perspectives with the application of the multi-disciplinary approach and surgical techniques developed in the treatment of congenital deformities resulting in considerable reduction in the period of hospitalisation.