Biomedical subjects
Publications and source records attributed to O Heymans.
Scuba diving is an occupation with a still growing expansion. Like every sport it has its own specific pathologies. Some accidents can be very serious and life-threatening. We discuss the 3 main groups of accidents: barotraumatism, gas toxicity and accidents related to aquatic environment. The knowledge of the mechanisms underlying these accidents leads to a less risky approach of scuba diving.
Fractal geometry has become very useful in the understanding of many phenomena in various fields such as astrophysics, economy or agriculture and recently in medicine. After a brief intuitive introduction to the basis of fractal geometry, the clue is made about the correlation between Df and the complexity or the irregularity of a structure. However, fractal analysis must be applied with certain caution in natural objects such as bio-medical ones. The cardio-vascular system remains one of the most important fields of application of these kinds of approach. Spectral analysis of the R-R interval, morphology of the distal coronary arteries constitute two examples. Other very interesting applications are founded in bacteriology, medical imaging or ophthalmology. In our institution, we apply fractal analysis in order to quantitate angiogenesis and other vascular processes.
To evaluate the efficiency of emergency suction in extravasation injuries of contrast medium, records of 11 patients treated for extravasation injuries with a combination of suction and saline washout were reviewed. All of the patients were treated in the first 2 hours after injury. The mean extravasated volume was 55 cc. There were no surgery-related complications, and all the patients experienced a relief of their preoperative pain. Except for two patients with blisters at admission, none of them suffered skin or soft-tissue necrosis. Mean time to complete healing was 9 days. Emergency suction therapy is safe and effective in preventing the skin and soft-tissue necrosis associated with extravasation injuries of hyperosmolar contrast medium.
Although pressure sores occur frequently during the evolution of paraplegic patients, they can present in patients confined to bed or in casts. Ischiatic, sacral and trochanteric sores are the most frequent. For stade III & IV lesions surgical excision followed by a coverage with healty tissue remain the only right principle. Usually, flap transfert meats these requirements. However, the selection of the surgical procedure and the post-op care are the main factors for a successful treatment.
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Surgically assisted rapid maxillary expansion is an accepted method for correction of transverse skeletal and dental discrepancies. The surgical technique includes a Lefort I osteotomy with medial palatine osteotomy. The maxillary must be totally released to achieve the desired expansion. There are several advantages: bone apposition in osteotomy sites, reduced risk of dental version or extrusion compared with orthopedic care, secondary surgical cure of complex dysmorphism requiring fewer segmentary osteotomies. Finally, we examined skeletal side effects induced by surgically assisted rapid maxillary expansion in the vertical and sagittal dimension of the face.
Endoscopic surgery is slowly becoming an increasing part of plastic surgical practice. Besides its most obvious advantages, related to small incisions, the endoscope provides excellent magnification of the operative field. We thus decided to investigate the possibility of using the endoscope as an alternative to the operative microscope for performing microsurgical procedures. Before starting a clinical investigation, digital artery, nerve, vein microsutures, and neck dissections were performed in fresh human cadavers. Magnification, working distance, depth of focus, diameter and temperature of the operative field, and resolution were measured using either the operating microscope or the endoscope. Working conditions were compared. The advantages of the endoscope as compared to the microscope were: less bulk, sterility, mobility, versatility and cost-effectiveness. The disadvantages were: short working distance, inferior resolution and two-dimensional images. Overall, the endoscope was found to be an interesting alternative to the operating microscope. We are now using the endoscope routinely in the clinical arena, and we believe that it has a great potential and a promising future as a microsurgical tool.
Facial wounds are frequently associated with bone fractures and multiple trauma; however, disruption of the parotid gland or Stensen's duct is rare and is often associated with facial nerve palsy. Lesions are often undiagnosed on first assessment of the multiple trauma patient. If microsurgical repair of Stensen's duct provides good functional results, ignoring such lesions often leads to later complications such as fistulae and sialocoeles. Although simple ligation of Stensen's duct has been reported to give satisfactory results, the authors prefer a more anatomic reconstruction of this structure whenever possible. A case of Stensen's duct microsurgical repair using a vein graft are reported.
The historical background of solitary and multiple myxoid tumors of the dermis is accompanied by a confusing conglomeration of names. We report a case whose histologic features do not fit exactly with previous classifications. It appeared as a solitary angiomyxoma of the face containing stellate pleomorphic cells and exhibiting a locally infiltrative behavior with tendency for recurrences over more than 25 years. This recurrent pleomorphic solitary angiomyxoma appears to be distinct from cutaneous myxomas that exhibit a very low local recurrence rate and from malignant tumors with myxoid deposits. The treatment consisted of a wide surgical excision.
BACKGROUND: Recent advances in angiogenesis research have led to the introduction of new prognosis factors. Although the vessel count is effective in breast cancer, the prognosis of primary cutaneous melanoma (PCM) does not seems to be directly influenced by this parameter. However, the microscopic examination of PCM suggests variability in the repartition of the microvasculature. OBJECTIVE AND METHOD: To explore the possibility of extracting information about the vessel distribution by performing a textural analysis on the grey level of histological sections by means of fractal characterization by both Fourier spectrum and multifractal analysis. RESULTS: Three different patterns of vasculature were identified according to the vessel density and distribution. CONCLUSION: It is possible to differentiate and quantify clearly the differences in the microvessel profile organization using the fractal and multifractal methods.
Progression and metastatic spread of primary cutaneous melanoma (PCM) is largely predicted by the thickness of the primary tumor. However, the accretive or proliferative pattern of growth of PCM is another aspect that might affect the prognosis. We retrieved from our histopathological files 11 superficial spreading PCM which had been documented to show an almost stable size for at least 3 years before excision. The area of the PCM at the skin surface had been measured by planimetry on the excision specimens. Histological sections were used to measure the maximum thickness of the neoplasms. A PCM volume estimate was derived by multiplying the surface area by the thickness of the tumors. In addition, the vessel area was determined beneath and outside the PCM lateral margins on Ulex europaeus agglutinin-1-stained sections using computer-assisted image analysis. Peritumoral vascularity was significantly more developed than at distance of the neoplasms. A significant negative exponential correlation was yielded between the peritumoral vascularity and the PCM volume estimate. Such vascular eclipse might be the cause of clinical PCM dormancy. However, other possible independent mechanisms are not ruled out by the present study.
The Mosan Study Group of Pigmented Neoplasms was founded about 15 years ago. It has collected more than 20,000 cutaneous malignancies including melanomas and basal and squamous cell carcinomas. The incidence of these cancers is on the rise in Wallonia. In particular, malignant melanomas represent a spectrum of emerging cancers characterized by a proteiform biological outcome. They mostly affect young women. The major risk factor appears to be iterative and unwise ultraviolet exposures. The prevention of melanomas is basically founded on such a dogma and accordingly relies on sunscreens. However, controversies about their beneficial effects are rife and fueled by axiomas and contradictory sophisms. At the exception of surgery, the therapeutic options for the diverse types of melanomas do not yet fulfill the scope of evidence-based medicine.
Extra-abdominal desmoid tumors are locally aggressive benign soft tissue tumors arising from the connective tissue of muscle and overlying fascia or aponeuroses. Location around the hip occurs in about 10% of all desmoid tumors. The authors report the development of a desmoid tumor around the hip 45 months after implantation of a total hip prosthesis. Endocrine and physical factors seem to play an important role in the development of the disease. Moreover, an association has been reported between trauma and desmoid tumor. Desmoid tumors developing around silicon implants have also been described. However, no association between hip prostheses and desmoid tumors has been published in the world literature. Although soft tissue tumors induced by metallic implants have been observed clinically, we still seek a coherent explanation for the exact pathogenesis.
Venous aneurysms are uncommon in the vascular pathology of the lower limb. They are more commonly encountered in the neck, thoracic veins and visceral veins. Involvement of the popliteal veins is not often encountered. These aneurysms often cause thrombosis and subsequently pulmonary embolism. Phlebography and duplex scanning give the most accurate diagnosis. As the risk of associated pulmonary embolism is high, elective surgery is recommended since it has been proven that proper anticoagulation treatment does not prevent the risk of pulmonary embolism.
Fractal analysis is widely used in many scientific fields, including the study of vascularization. It is a convenient method that defines the complexity of natural structures. The chorioallantoic membrane of the chick embryo is a standard experimental model for the study of vasculogenesis and angiogenesis. The aim of this investigation was to demonstrate that fractal geometry is more appropriate than any other method to describe and analyse the evolution of a vascular network, i.e. the extraembryonar vascular network of the chick embryo. We used an original methodology to evaluate the complexity of this network in the first stages of embryo development (day 3 until 6). We demonstrated an increase of fractal dimension, indicating an increasing complexity of the vascular tree, until an asymptotical value of about 1.70 at day 4. The fractal approach is more accurate than other usual semi-quantitative or quantitative methods evaluating the complexity of a growing vascular tree.
Lipomatous tumors are very frequent; simple lipoma is the most common variety. According to Enzinger, lipomatous tumors are classified into five different groups: simple lipomas, variant lipomas forms, heterotopic lipomas, infiltrating lipomas and lipomatosis, and finally hibernomas. Usually, lipomatous tumors are characterized by a slow, unpainful, growth. Classical treatment includes surgical resection. The clinical diagnosis is confirmed by histology. Liposucion can be a therapeutic option in certain cases.
Intramuscular myxoma is a rare, benign, mesenchymal tumour. It contains fibroblast-like, histiocyt-like and myofibroblast-like cells in a myxoid material. These tumours occur in adults between 40 and 60 years with a predilection for women (70%). The incidence varies between 0.10 and 0.13/100.000. They may occur as an independent lesion or in conjunction with fibrous dysplasia or Albright syndrome. Although only circumstantial features have linked fibrous dysplasia and myxoma, the concept of a basic metabolic error of both tissues during initial growth period has been proposed. There are no specific clinical manifestations of this tumour. Although MRI offers the best imaging approach in terms of determination of the local extension of the tumour and its fatty texture, the differential diagnosis between intramuscular myxoma and myxoid degenerescence of a liposarcoma must be considered. The diagnosis is always made after microscopic examination. Local excision with histological margins free of tumour provides excellent local control without recurrence. The case of a patient presenting this rare tumour is presented. A thorough survey of the literature was done.
Camurati-Engelmann disease is an uncommon condition, radiologically characterized by symmetric diaphyseal sclerosis involving the tubular bones. Clinical features include limb pain, muscle weakness, waddling gait and sometimes deafness. The evaluation is made by conjunction of radiographic and scintigraphic data. Corticosteroids and analgesics improve the quality of life, decrease the pain but do not alter the course of the disease. The evolution is unpredictable. The history of a 23 year old male with such a disorder is presented hereafter. His clinical course shows a very good response to the administration of corticosteroids, whereas no improvement is observed as far as the radiographic and isotopic features are concerned.