Silicon micromachined ultrasonic scalpel for the dissection and coagulation of tissue.

This work presents a planar, longitudinal mode ultrasonic scalpel microfabricated from monocrystalline silicon wafers. Silicon was selected as the material for the ultrasonic horn due to its high speed of sound and thermal conductivity as well as its low density compared to commonly used titanium based alloys. Combined with a relatively high Young's modulus, a lighter, more efficient design for the ultrasonic scalpel can be implemented which, due to silicon batch manufacturing, can be fabricated at a lower cost. Transverse displacement of the piezoelectric actuators is coupled into the planar silicon structure and amplified by its horn-like geometry. Using finite element modeling and experimental displacement and velocity data as well as cutting tests, key design parameters have been identified that directly influence the power efficiency and robustness of the device as well as its ease of controllability when driven in resonance. Designs in which the full- and half-wave transverse modes of the transducer are matched or not matched to the natural frequencies of the piezoelectric actuators have been evaluated. The performance of the Si micromachined scalpels has been found to be comparable to existing commercial titanium based ultrasonic scalpels used in surgical operations for efficient dissection of tissue as well as coaptation and coagulation of tissue for hemostasis. Tip displacements (peak-to-peak) of the scalpels in the range of 10-50 µm with velocities ranging from 4 to 11 m/s have been achieved. The frequency of operation is in the range of 50-100 kHz depending on the transverse operating mode and the length of the scalpel. The cutting ability of the micromachined scalpels has been successfully demonstrated on chicken tissue.

Optical characterization of fully programmable MEMS diffraction gratings.

We have fabricated and characterized fully programmable diffraction gratings consisting of 64 silicon micro-mirrors. The mirrors are 700µm long and 50µm wide with a fill factor of 90%. They are actuated electrostatically and move down by 1.25µm while showing negligible cross-talk and bowing as small as 0.14µm over 700µm. Extinction ratio up to 100 has been achieved by adjusting only 3 adjacent micro-mirrors. The gratings could operate either as light modulators up to 5µm or spectra generators up to 2.5µm.

Maximum likelihood estimators in magnetic resonance imaging.

Images of the MRI signal intensity are normally constructed by taking the magnitude of the complex-valued data. This results in a biased estimate of the true signal intensity. We consider this as a problem of parameter estimation with a nuisance parameter. Using several standard techniques for this type of problem, we derive a variety of estimators for the MRI signal, some previously published and some novel. Using Monte Carlo experiments we compare the estimators we derive with others previously published. Our results suggest that one of the novel estimators we derive may strike a desirable trade-off between bias and mean squared error.

[Traumatic superior orbital fissure syndrome: report of 4 cases and review of literature]. / Syndrome de la fissure orbitaire supérieure post-traumatique: à propos de 4 cas et revue de la littérature.

PURPOSE: The authors retrospectively analyzed four cases of posttraumatic superior orbital fissure syndrome and reviewed the literature. METHOD: Four patients (three male and one female) were followed for this complication in the department from october 1995 to december 1996. RESULTS: The mean age was 31 years, the median follow-up was 8 month. Computed tomography showed involvement of the superior orbital fissure but no in three patients, in the fourth. The treatment consisted of osteosynthesis of craniofacial fracture in three patients and corticosteroid therapy in the last one. All patients presented partial recuperation of external ophthalmoplegia and ptosis. Twelve months after the traumatism, one patient underwent surgery for persistant ptosis and diplopia. CONCLUSION: The superior orbital fissure syndrome is an exceptional complication of orbital traumas. Partial recuperation of the neuro-ophthalmologic function usually occurs within a period of several months.

Postoperative maxillary cyst following sinus bone graft: report of a case.

Sinus bone grafting with autogenous bone is routinely performed to allow placement of endosseous dental implants. Although numerous maxillary sinuses have been successfully grafted, some complications of this procedure have been reported. These include maxillary sinusitis, resorption, infection and possible failure of grafts, loss of implants after 1-stage surgery, and oroantral fistulae. Only one case of postoperative maxillary cyst developing in the graft has been reported in the literature. Here, the authors report a similar case that necessitated grafting of the cyst with autologous iliac bone.

[Orbital filling using a vascularized parietal bone graft: a case report of rehabilitation with an orbital graft of axial implants]. / Comblement orbitaire par greffe osseuse pariétale vascularisée: à propos d'un cas de réhabilitation par épithèse oculopalpébrale sur implants axiaux.

Orbital and intracranial complications of dental cellulitis are exceptional. The authors report such a case with orbital cellulitis and frontal abscess that dictated orbital exenteration with resection of the eyelids. Before realization of an implant supported epithesis, the orbit was filled with a prefabricated vascularized fascio-osseous parietal bone flap. This allowed placement of two extra-oral fixtures (Nobel biocare) in an antero-posterior axis. In some cases, preimplant orbital bone graft appears to be the only solution when implant placement in the orbital rim is impossible or contra-indicated. Indications, advantages and disadvantages of this technique will be discussed.

[Post-traumatic enophthalmos. Physiopathologic considerations and current therapeutics]. / Enophtalmies post-traumatriques. Considérations physiopathologiques et thérapeutiques actuelles.

The article is an overview of the available literature on post-traumatic enophthalmos (PTE). The PTE has a clinical definition and its diagnosis is based on a clinical examination. Fully assessment of the deformity requires complete ophthalmological examination and a measurement of the globe backward displacement by the mean of Hertel's ophthalmometer. Focusing on the pathophysiology, we insist on the role of periorbit and extraocular muscle retraction; nevertheless, according to most of the author's, opinion, the main pattern of the PTE seems to be the increased orbital post-traumatic volume, as it can be demonstrated by computed tomography (CT scan). In fact, thorough evaluation of the deformity needs at less a CT scan examination, providing horizontal and coronal slices. Sometimes, even a three-dimensional reconstruction can be obtained, helping the surgeon assessing the orbital deformity pre-operatively. We present five patients victims of a high-energy facial injury (motor vehicular accidents is responsible for an overwhelming majority of cases) leading to severe orbital lesions, and presenting a PTE as the main sequelae. We use homologous bone grafts to repair orbital fractures, especially calvarial bone. Osteotomy of the zygomatic bone (total or partial) can be proposed, combined with grafting of the orbit, to improve the correction of PTE. Most of all, patients with acute orbital trauma must be operated on as quick as possible: the sooner the surgery, the lower the probability for the PTE to occur.

[Parietal grafts in maxillofacial and pre-implant surgery]. / Les greffons pariétaux en chirurgie maxillo-faciale et pré-implantaire.

Due to the recent regulations generated by the diversity of infectious risks, autologous bone is the standard graft material in maxillofacial surgery. Although synthetic biomaterials can be useful, they remain insufficient in many situations. Among the many sites offering graft material, monocortical parietal bone which is accessible within the craniocephalic operative field has distinguishing characteristics due to its membranous embryological origin and its mode of direct ossification which does not include a cartilaginous stage. The proportion of cancellous bone per unit volume is much higher than in enchondral bone (iliac bone, ribs...). These factors are undoubtedly the source of its main qualities--very little resorption and excellent capacity for bony integration--motivating its increasingly widespread use over the past twenty years. We present our experience in a series of patients who underwent surgery between 1992 and 1997. Parietal bone was used for orthognathic, pre-implant or reconstruction surgery after trauma or carcinological trauma. We present a description of the surgical procedures together with morbidity results and compare our findings with those found in large series in the literature, particularly concerning rare neuromeningeal complications. We discuss indications for parietal grafts and their course at the receiver site.

Mesenchymal chondrosarcoma of the jaws. Report of four cases.

Mesenchymal chondrosarcoma (MCS), described in 1959 by Lichtenstein & Bernstein, is a very rare malignant tumour. Only 46 cases have been previously reported in the jaws. Over a period of 30 years, four chondrosarcomas of mesenchymal type (of which one has already been published in 1987 with a three-month follow up) were treated in our department. Two patients have been followed for more than 17 years, of whom one has died of an intracranial extension and the other is still alive after surgical treatment of numerous recurrences and metastases. The two others are tumour-free with a follow up of 18 months and 11 years respectively. Histological, epidemiological and clinical features and treatment of MCS are discussed relevant to the data published in the literature.

Myositis ossificans progressiva: five generations where the disease was exclusively limited to the maxillofacial region. A case report.

Myositis ossificans progressiva is an unusual autosomal-dominant inherited disease characterized by congenital malformations and osseous metaplasia of the fascia of the muscles and connective tissue leading to ossification of the relevant area. The case report is remarkable in that eight members of the same family over five generations manifested the exclusive localization of the disease in the maxillofacial region.

[Florid cemento-osseous dysplasia: a poorly recognized entity. Apropos of 5 cases]. / La dysplasie cémento-osseuse floride: une entité mal connue. A propos de cinq cas.

We present five cases of florid osseous dysplasia observed in our department. There has been some confusion as to the terminology of this entity. We present here a review of the literature and outline the histological classification among odontogenic tumors as well as their epidemiology. The orthopantomogam is the mainstay radiological exploration, sometimes in association with a CT-scan. There are three main differential diagnoses: Paget's disease, Gardner's syndrome located in the maxillofacial area and diffuse sclerosing osteomyelitis. Asymtomatic forms motivate therapeutic abstenstion. When inflammatory, infectious or morphological complications appear, treatment relies on surgery in combination with long-term antibiotic regimens.

Infrahyoid myocutaneous flap in reconstructive maxillofacial cancer and trauma surgery.

We report the use of an island infrahyoid myocutaneous flap, pedicled on the superior thyroid vessels, in a group of 21 patients. This flap allows reconstruction of intraoral defects or defects of the lower portion of the face, as large as 10 x 4 cm. We used it in 15 cases to repair parts of the oral cavity, after tumour resection, in 2 patients with mandibular osteoradionecrosis and in 4 patients with gunshot injuries. Among the 21 flaps, no muscular necrosis was observed; however, 4 total necrosis and 4 partial necrosis (< or = 25% of the skin area) of the skin paddle were recorded. Loss of the skin paddle was primarily attributable to the anatomical variations of the veins draining this flap.

[Diffuse cervical cellulitis apropos of 15 cases]. / Cellulites cervicales diffuses à propos de 15 cas.

A homogeneous series of 15 cases of diffuse cervical cellulitis originating in the oropharyngeal area were collected from December 1990 to April 1995. Despite early management, diffusion of the infectious processus was rapid with extension and development of severe mediastinal or pulmonary complications. When diffuse cervical cellulitis is suspected, early and adapted aggressive treatment must be initiated immediately: suppression of the causal factor, surgical exploration with repeated drainage depending on the clinical course assessed on CT scans, antibiotics effective against the aero-anaerobic flora. This aggressive attitude is required to avoid potentially severe morbidity. Anti-inflammatory drugs, taken alone or with unadapted antibiotics was implicated in 11 cases as a favoring factor.

[Continuous elastic skin expansion for closure of the loss of substance of the scalp]. / Extension cutanée élastique continue pour fermeture d'une perte de substance du cuir chevelu.

The authors present a case report of a traumatic defect of the scalp involving all layers including galea and periost measuring 10 x 14 cm. The surgical repair of the scalp avulsion was obtained in 3 weeks using Continuous Skin Extension procedure with Kirschner pins threaded through the wound margins, held together with elastic bands. Traction forces were modified twice a week in our patient basis. No undermining was necessary. The authors analyse the benefits of this technic and describe the alternative surgical procedure. This technique is easy to handle, cheap, safe, and requires a single surgical step. Furthermore, it quickly allows the patient to proceed with his work.

[Chondrosarcoma of the temporomandibular joint. Apropos of a case and review of the literature]. / Chondrosarcome de l'articulation temporo-mandibulaire. A propos d'un cas et revue de la littérature.

Chondrosarcomas of the temporo-mandibular joint are exceptional and have been previously reported in the literature in only seven cases. A case located in the temporal bone with extension in the infratemporal fossa and the cranial base is presented. Treatment consisted in a wide surgical resection combined with postoperative radiotherapy. The patient is alive with a follow-up of more than two years.

[Treatment of obstructive sleep apnea syndrome using a mandibular advancement prosthesis: review of the literature]. / Le traitement du syndrome d'apnées obstructives du sommeil par les prothèses mandibulaires d'avancée: revue de la littérature.

The treatment of OSAS with prosthetic devices displacing forward and lowering the mandible in order to increase the size of the pharyngeal airway is seldom used at present. Some recent publications attracted our interest and we deemed it of interest to review them. Our work is mostly concerned with objective results as assessed by polysomnography, and also with cephalometric changes caused by the device. In spite of equivocal results at polysomnography, which seldom met commonly accepted criteria of successful treatment, indiscutable therapeutic successes have been reported. Therefore, this simple, reversible and cheap devices could be advocated in cases of mild or moderate OSAS. However, their role in the therapeutic armamentarium of OSAS as well as their indications and efficacy need to be better assessed.

[Paradental cyst]. / Le kyste paradentaire.

The paradental cyst is an odontogenic inflammatory cyst (WHO classification, 1992). It has been rarely described in the french literature and includes: The inflammatory paradental cyst which occurs on the buccal or distal aspects of an erupted third mandibular molar or of a canine (first description by Main in 1970); the mandibular infected buccal cyst which occurs on the buccal surface of the mandibular second or first molar in children around 6-8 years of age with an associated history of inflammatory signs (Stoneman and North, 1993). The histological features are the same as those of the radicular cyst. Prognosis is excellent after enucleation. This paper present an additional case report of a paradental cyst located on a second mandibular molar.

[Orbital paraganglioma. Apropos of a case and review of the literature]. / Paragangliome orbitaire. A propos d'un cas et revue de la littérature.

Paragangliomas are exceptional in the orbit. Among the 47 cases reported in the world literature more than 1/3 has been classified as alveolar soft part sarcoma. Diagnosis of paraganglioma was confirmed on the basis of pathology reports in only 10. We observed a case in a 46-year-old woman who presented with a tumour of the orbit. The histology examination and the ultrastructure determined by electron microscopy confirmed the diagnosis of paraganglioma. Characteristic histologic features are discussed together with a review of the literature.

[A comparative study of rhabdomyosarcoma with cervicofacial involvement in children and adults. A therapeutic protocol]. / Etude comparative des rhabdomyosarcomes à localisation cervico-faciale chez l'enfant et chez l'adulte. Protocole thérapeutique.

Rhabdomyosarcoma is a malignant tumour of striated muscles. It is usually encountered in children and rarely in adults. In this study we compared sex ratios, aetiologic factors, different localizations, development stages, modes of extension and treatment as well as prognosis in children and adults with cervicofacial localizations. The differences observed led to the conclusion that cervicofacial rhabdomyosarcomas in children and adults are two very different pathological entities.