Biomedical subjects

L A Whitaker

Publications and source records attributed to L A Whitaker.

At least 37 records · Page 2Linked to original sources

PubMed1995

Cerebellar atrophy in a patient with velocardiofacial syndrome.

Velocardiofacial syndrome and DiGeorge syndrome have not previously been associated with central nervous system degeneration. We report a 34 year old man who presented for neurological evaluation with cerebellar atrophy of unknown aetiology. On historical review, he had neonatal hypocalcaemia, an atrial septal defect, and a corrected cleft palate. His physical examination showed the characteristic facies of velocardiofacial syndrome as well as dysmetria and dysdiadocho-kinesia consistent with cerebellar degeneration. Molecular cytogenetic studies showed a deletion of 22q11.2. This man is the first reported patient with the association of a neurodegenerative disorder and 22q11.2 deletion syndrome.

Abnormalities, Multiple↗

PubMed1994

The role of pressure on regulation of craniofacial bone growth.

The regulatory role of pressure on growth and differentiation of the craniofacial skeleton is largely unknown. We devised an experimental model to determine if the graded application of pressure could exert a trophic influence on craniofacial bone, allowing deliberate alteration and reshaping of the facial skeleton. To examine this question, 18 kittens were used to determine the adverse morphological sequelae after orbital evisceration and to compare the ability to remedy such facial deformity with the use of an inert implant or pressure-induced tissue expansion. In addition to detailed craniometric measurements of the cranial, orbital, and midfacial regions, histological analyses as well as radiographic and gross morphological comparisons were evaluated. Our results demonstrate a severe asymmetry and constriction in the orbital and midfacial regions resulting from orbital evisceration in the growing kitten. Placement of an inert implant will help to ameliorate only some of these adverse sequelae, whereas graded application of pressure appears to direct craniofacial bone growth, resulting in normal bony histology and improved facial form. We affirm that regional growth disturbances can alter normal facial development and that the regulatory role of pressure on bone growth can be exploited to dynamically correct abnormal craniofacial anatomy.

Analysis of Variance↗

PubMed1994

Hyaluronic acid-filled mammary implants: an experimental study.

Issues of radiolucency and biocompatibility of currently available mammary implants have prompted the search for alternatives. Several new filler materials have been suggested recently but have involved the use of materials foreign to the body. We have studied the use of a naturally found polysaccharide molecule, hyaluronic acid, as an alternative filler material to silicone gel. We tested hyaluronic acid-filled implants using standard mammographic techniques, applanation tonometry, and in an in vivo animal model (n = 24) up to 1 year after implantation. The present study demonstrates that hyaluronic acid-filled implants have softness comparable with that of silicone gel and saline implants and are more radiolucent, allowing better visualization of breast structures around the implant. Furthermore, in vivo studies fail to demonstrate any adverse reactions to the material over a period of 1 year. Hyaluronic acid has unique properties in modulating the process of wound healing, and these properties may be applied to the tissues surrounding the implants as a result of leaching of hyaluronic acid through the covering shell. Although further studies using larger volumes of filler, characterization of the hyaluronic acid within the implant, quantification of the exact amounts of hyaluronic acid leached into surrounding tissues, and a more appropriate primate model need to be undertaken, this pilot study points out that there may be more biologically compatible materials for the use in breast implants that warrant further investigation.

Animals↗

PubMed1993

An objective assessment of treatment for orbital hypertelorism.

A retrospective statistical analysis of orbital hypertelorism correction was performed by comparing the preoperative and postoperative intercanthal distances of these patients with published age-matched normal values. Forty-five patients who had undergone surgery over a 15-year period with an average follow-up of 5 years (6 months to 14 years) were evaluated. Comparison of age-normalized preoperative and postoperative intercanthal distances revealed a significant difference for orbital hypertelorism patients as a group (p < 0.0001), patients with clefts (p < 0.0001), patients with nasoencephalocele (p < 0.01), and patients with frontonasal dysplasia (p < 0.05), but not for those patients with craniofacial dysostosis (p < 0.20). Multiple analyses of variance revealed a significant interaction existing between the extent of preoperative deformity and the cause of hypertelorism for both the postoperative deformity and the total amount of correction achieved, but not for the type of surgery or for the age at which the surgery was performed.

Analysis of Variance↗

PubMed1993

Massive teratomas involving the cranial base: treatment and outcome--a two-center report.

Massive teratomas involving the cranial base are extremely rare, and to our knowledge, there are no reports of this condition in surviving children. We describe the management of four cases of massive intracranial teratomas, reflecting a combined experience from two major referral centers. We found that when corrected at an early age, the brain parenchyma demonstrated a remarkable ability to reexpand in those children who had appeared to have sustained parenchymal deficits secondary to the mass effect from the tumor. Follow-up thus far suggests that regional skull growth potential may be compromised in some of these patients. Often, the exact pathologic diagnosis of these entities is somewhat different, since they may fall somewhere within the hamartoma-heterotopia-teratoma continuum. We believe that the best care of these children is offered through a combined simultaneous craniofacial and neurosurgical approach.

Child, Preschool↗

PubMed1993

Spatial ability and land navigation under degraded visual conditions.

Land navigation tasks require the use of visual cues. When these cues are degraded by the loss of resolution, navigators suffer varying degrees of performance decrements. We tested the hypothesis that these decrements are less severe for people of high spatial ability than they are for people of low spatial ability. We tested 108 noncommissioned officers on a task that required them to determine if two woodland photographs taken from different directions (N, NE, E ... NW) were of the same location; spatial ability was assessed using the Cognitive Laterality Battery. Spatial ability was related to the ability to do this task. Furthermore, there was a significant interaction between spatial ability and visual resolution on recognition performance. This article discusses the implications of these results for teleoperations and land navigation.

Cognition↗

PubMed1993

Complications with facial advancement: a comparison between the Le Fort III and monobloc advancements.

Certain procedures for facial advancement may carry greater risk than others. While many believe that separating the cranial base by monobloc advancement leads to a higher complication rate, no comparative series between the Le Fort III and monobloc advancements has ever been reported. We reviewed our series of these different techniques. Over a 15-year period, 29 patients underwent 30 surgical procedures, with either a midfacial or frontofacial advancement. The average age of patients at the time of surgery was 12 years, with a range from 3 to 26 years. There were 20 Le Fort III and 10 monobloc advancements. Follow-up averaged 4 years, with a range from 10 weeks to 13 years. There were no deaths in this series. The infectious complications differed significantly between the two groups, with all major infections occurring in the monobloc group. The noninfectious complications (2 major and 20 minor) were proportionately distributed between the Le Fort III and monobloc groups. Aesthetic results of the midface, judged by the percentage of revisions necessary, were found to be the same between the two procedures. Aesthetic results were noted to correlate strongly with age at the time of surgery, with the older patients being judged as having a better aesthetic result and most of the younger patients requiring a repeat of the facial advancement. We conclude that while we were unable to determine any definitive aesthetic advantage of one procedure over the other in our series, there was a significantly higher infection rate with the monobloc advancement. On the basis of these results, we recommend a staging of the forehead and midfacial advancements.

Adolescent↗

PubMed1993

Assessment of the preferred vertical position of the ear.

To determine the most desirable ear level (vertical position), a set of four drawings was assessed by 40 observers. Two levels were almost equally preferred when viewed in profile, one with the upper edge of the ear at the level of the most lateral point of the eyebrow and the other with the upper edge at the height of the upper eyelid. Various factors affecting the visual impression of auricular level and their clinical significance are discussed.

Adolescent↗

PubMed1992

Age-related changes of the craniofacial skeleton: an anthropometric and histologic analysis.

With the development of increasingly sophisticated methods for the alteration of bony facial form consequent to age, it is imperative that the surgeon have a fundamental knowledge of the age-related changes the skeleton may undergo. To understand these changes better, a detailed anthropometric and histomorphic analysis of the craniofacial skeleton as a function of age was undertaken. The study consisted of a detailed craniometric analysis of 160 skulls selected randomly from a Caucasian population of skeletal remains totaling 1500 specimens. Additionally, a histologic analysis of the supraorbital ridge in a separate preserved cadaver population was performed. Although the results showed individual variation as expected, definite changes in craniofacial morphology were observed. These included (1) appreciable reduction of facial height, most marked in the maxilla and mandible, and strongly correlated with loss of teeth, (2) modest increase in facial width, (3) modest increase in facial depth, except in those regions associated with tooth loss, and (4) general coarsening of bony prominences. Histomorphic analysis demonstrated increasing porosity with age, more marked in the female population. Although these changes represent population trends, in any given patient, any or all of them may be present to varying degrees. Surgeons should be aware of these possibilities and consider selective alterations of the skeletal foundation, either separately or in concert with the overlying soft-tissue envelope, in order to optimize the results of surgery for the aging face.

Adult↗

PubMed1991

An experimental study on the effect of rigid fixation on the developing craniofacial skeleton.

Rigid fixation of the craniofacial skeleton has proven of great value in adult orthognathic and traumatic reconstructive surgical procedures. This technique has gained increased acceptance in the surgical treatment of infants and young children with congenital malformations, despite the fact that its effects on subsequent craniofacial growth are unknown. To examine this question, an experimental model using 25 young kittens was developed to compare rigid fixation with conventional wire fixation, with and without osteotomy. Our findings demonstrate a regional restriction of growth in the developing craniofacial skeleton when both wire and plate and screw fixation are utilized in concert with osteotomy. Further, a compensatory growth was observed in individual animals when plate fixation was utilized that was not seen in the wire-treated group. This suggests that there is a dynamic growth interaction between restriction and compensation in this setting.

Animals↗

PubMed1991

Aesthetic augmentation of the posterior mandible.

The posterior mandible begins just behind the mental nerve and second bicuspid bilaterally, extends to the posterior edge of the ramus, and then runs superiorly to the zygomatic arch. Augmentation of the posterior mandible is possible by use of a synthetic implant that is tailored individually to each patient's specific needs. Implant plant thickness varies from 4 to 8 mm, with an average thickness of 6 mm. Careful preoperative planning is done based on an aesthetic assessment of the amount of highlighting desired, thickness of the soft tissues, and the use of life-size photographs and cephalometric and Panorex x-rays. A pattern is cut, and the implant is carved to fit the patient. Insertion of the material after careful tailoring to the individual patient's own mandibular size and configuration requires a generous posterior lower buccal sulcus incision. Antibiotic irrigation and systemic antibiotics are essential, and careful closure in two layers completes the procedure. One implant in the series extruded in a patient who had had radiation therapy, and one patient required repositioning of the implant. Otherwise, in 22 patients there were no infections or permanent morbidity. The procedure seems to be a realistic and safe one for both the youthful and aging face, as demonstrated in patients in this series, with ages varying from 16 to 40 years.

Adolescent↗

PubMed1991

Intraosseous vascular malformations of the orbit.

Intraosseous vascular malformations are rare benign tumors involving the bones of the orbit. The diagnosis should be considered when a patient presents with an enlarging mass fixed to bone in the upper face, and the characteristic x-ray appearance should be looked for on plain films. Treatment is local excision of the bone containing the tumor and immediate reconstruction with autogenous bone.

Adult↗

PubMed1991

Facial reconstruction consideration in rheumatic diseases.

In conclusion, the management of facial involvement in JRA, Romberg disease, and scleroderma is dictated by the degree of severity of the disease, age of onset, and length of activity. Functional occlusal abnormalities are best addressed through a team approach consisting of initial orthodontics followed by orthognathic surgery if needed. In all types of scleroderma, surgical facial reconstruction is best delayed until the disease is quiescent for at least a year. The ideal option for facial skeletal and soft-tissue augmentation has not yet been realized. Careful surgical planning and choice of grafts, flaps, or implants are critical to obtain the desired result.

Arthritis, Juvenile↗

PubMed1991

The skeletal treatment of orbital hypertelorism.

Orbital hypertelorism, strictly defined as an increase in bony interorbital distance, is not itself an isolated syndrome, but is instead an anomaly that may occur as either part of a syndrome or malformation sequence. Evaluation of orbital hypertelorism and the various anomalies that accompany it is best performed by a multidisciplinary craniofacial team. The timing of surgery involves considerations of multiple variables, but when performed can offer marked cosmetic improvements. Equally important as the skeletal surgery is correction of the associated soft-tissue problems.

Child↗

PubMed1991

Evaluation of facial skeletal aesthetics and surgical planning.

Proper surgical planning for aesthetic facial skeletal surgery requires of the surgeon not only intimate knowledge of available techniques but also an understanding of how and when to apply those techniques. To this end, proper facial form analysis is essential. In this introduction we have attempted to describe the elements of such an analysis, realizing that much remains to be learned about how the bone and soft tissue interact. In many ways the soft tissue--bone relations remain the unexplored area in aesthetic skeletal surgery. The further delineation of these relations by the use of anthropometry, laser light scanning, ultrasound, CT, and MRI remains an open area for investigation. The potential is enormous for using these data to study how bone and soft-tissue relationships combine to create facial form and how this form changes with both surgery and normal aging.

Esthetics↗

PubMed1991

Skeletal alterations as a basis for facial rejuvenation.

A slight decrease in overall facial bone bulk coupled with the increased soft-tissue expansion associated with aging produce effects that should be reversed in both the bone and soft tissue where possible. The changes are best done at the ledge areas: the supraorbital-temporal ridge areas, malar-midface, and chin mandible. However, the overall bone bulk may be increased in addition in the temporal fossae, in the infraorbital rim, at the lateral canthus, in the paranasal area, and at the alveolar ridges and dental areas. A combination of autogenous and synthetic materials is currently best, with synthetic materials most useful in the malar-midface, posterior mandibular, infraorbital, and paranasal areas. In the supraorbital ridge-temporal areas, it is a near equal choice between autogenous and synthetic materials. In the chin, the preferred method is by osteotomy using autogenous augmentation. The concept of increasing bone mass and decreasing expanded soft-tissue mass has application within the judgment of the surgeon coupled with the patient's desires. Subtle increases of bone mass to compensate for soft-tissue thinning as well as bone shrinkage, at the same time taking up lax soft tissue, can be done in conjunction with one another, effectively producing a three-layer face lift. The subperiosteal face lift is in reality an extended brow lift and can be used to enhance the brow-forehead area and the temporal, zygomatic, and paranasal areas. At the same time, the perioral, jowl, and submandibular regions must be treated by a combination of standard face lifting procedures and augmentation of the bone structures of the face.

Aging↗

PubMed1991

Temporal and malar-zygomatic reduction and augmentation.

The temporal fossa, zygomatic arch, and malar-midface should be considered jointly when augmentation of the temporal area or reduction of the zygomatic arch are to be carried out. These anatomic areas relate so closely to one another that altering one affects the other. In addition, augmentation of the malar-midface area may be done if one of the other two procedures is to be considered, or if a brow lift, subperiosteal face lift, or other reason for using a coronal incision exists. Use of the coronal incision for malar augmentation is probably not justified because of the large amount of surgery required in spite of the lesser morbidity associated with this approach in terms of amount of infections, lip stiffness, and hypesthesia. Planning a surgical procedure must be done in the office, by examining the patient at eye level to determine the amount of zygomatic arch reduction and the amount of temporal fossa augmentation necessary. Similarly, the three zones of the malar-midface complex must be assessed, with the amount of augmentation of each zone determined prior to the day of surgery. The surgical procedure is then executed through a coronal incision, with the dissection extending down to the zygomatic arch. If the temporal muscle is to be elevated out of its fossa, it is cut on its anterior, superior, and posterior edges, elevating it out of its fossa so that a Proplast implant, typically 3 to 4 mm thick and finely tapered on its superior and posterior edges, with suturing done anteriorly, may be inserted. The muscle is then resutured to its aponeurosis on all three edges. If the zygomatic arch and malar-midface area are to be approached, the dissection is carried to the deep and superior edge of the zygomatic arch, and the periosteal elevator is used to elevate the soft tissue off the lateral and inferior edge. The arch and malar-midface are cleared of soft tissue, extending the tunnel to the upper buccal sulcus. The arch is then reduced with a contouring burr to the thinness desired. Alternatively, the malar-midface area may be augmented with synthetic material precisely positioned, with a suture around the zygomatic arch, holding it in position as measured from the lateral orbital rim. The incision in the temporal fascia is then resutured, and the coronal incision is closed.(ABSTRACT TRUNCATED AT 400 WORDS)

Aluminum Oxide↗

PubMed1990

Secondary reconstruction of posttraumatic orbital deformities.

A retrospective analysis of our experience, techniques, and concepts for the secondary reconstruction of orbital injuries to 78 patients over a 15-year period is presented. Secondary orbital reconstruction has the following four basic steps: (1) freeing of the overlying soft tissues by extensive subperiosteal dissection; (2) skeletal reconstruction, usually with onlay bone grafting and contour osteoplasty; (3) restoration of palpebral shape and position by medial and lateral canthopexy; and (4) soft-tissue refinement. Reconstruction required an average of at least two operations. In this series, there were no mortalities, three infections, and no reoperations for bleeding. Thirty patients required a second operation to an area previously addressed reflecting inadequacies in technique, the unpredictability of bone grafts, and soft-tissue scarring. Distortion of the skeletal infrastructure is most amenable to secondary reconstruction. Soft-tissue distortions that accompany bone malposition are less well corrected. Soft-tissue contraction is the limiting factor in successful reconstruction dictating separate movement of the overlying soft tissues and ligaments, their overcorrection, and subsequent revisional surgery. Secondary orbital reconstruction, although providing significant improvement, usually fails to restore the preinjury appearance, and usually falls short of properly performed acute reconstruction.

Adolescent↗