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Biomedical subjects

R E Hayden

Publications and source records attributed to R E Hayden.

At least 37 records · Page 2Linked to original sources
PubMed1995

Reconstruction of the head and neck cancer patient with a vascularized fibula flap and dental implants: preliminary clinical report.

Reconstruction and rehabilitation of the head and neck cancer patient is challenging. Vascularized fibula grafts can be used to reconstruct mandibular defects after resection of the malignancy and the surrounding bone. Prosthodontic treatment can restore function and esthetics. This preliminary report discusses the use of endosseous implants in radiated mandibular vascularized fibula grafts after surgical resection.

Bone Transplantation↗
PubMed1995

Carotid artery invasion by head and neck masses: prediction with MR imaging.

PURPOSE: To determine the value of magnetic resonance (MR) imaging in predicting resectability of head and neck neoplasms around the carotid arteries. MATERIALS AND METHODS: Forty-nine patients (28 male patients and 21 female patients aged 17-79 years; mean, 57.3 years) with head and neck masses and clinical evidence of carotid wall invasion underwent MR imaging. T1-weighted, T2-weighted, and gadolinium-enhanced T1-weighted images were analyzed to determine circumferential involvement of 53 arteries by tumor. RESULTS: More than 270 degrees of circumferential involvement was considered suggestive of unresectability of the malignant neoplasm; 270 degrees or less was considered lack of invasion. The sensitivity of MR imaging for determination of unresectable disease was 100% (12 of 12 cases), specificity was 88% (36 of 41), and accuracy was 91% (48 of 53). Accuracy was 100% for squamous cell carcinoma (n = 29). CONCLUSION: Tumor that encompasses more than 270 degrees of the carotid artery probably cannot be removed from the artery. Tumor that involves 270 degrees or less of the artery can be removed.

Adolescent↗
PubMed1995

Cervical thorium dioxide granuloma ('thorotrastoma').

An elderly woman had an expanding cervical mass that entrapped and compressed the adjacent cranial nerves, blood vessels, and muscles. The mass was dense on radiographs, extended from the skull base to low neck in the prevertebral and parapharyngeal tissues, and showed mixed intensity on MR. A previous direct carotid arteriogram with thorium dioxide as the contrast agent suggested the histologically proved diagnosis of a cervical thorium dioxide granuloma ("thorotrastoma").

Diagnosis, Differential↗
PubMed1994

Development of thrombosis models in the rabbit.

OBJECTIVE: In an effort to decrease the probability of thrombosis at microvascular anastomotic sites, researchers have examined techniques for decreasing the probability of thrombus formation at these sites. Identification of an appropriate animal model that is relatively easy to perform, reliable, and reproducible was attempted in this study. The goal of this study is to provide other investigators with a comparison and critical appraisal of various thrombosis models allowing a more directed selection of models for their own research. DESIGN: A prospective, nonblinded animal study was designed that compared features of thrombosis models previously described in the literature with each other and with a new model (the "tuck" model), herein described. MAIN OUTCOME MEASURES: Ease of dissection, time to thrombosis, and other technical details were recorded. Additionally, validation of clot histologic features in the tuck model was performed. RESULTS: The inversion graft models were found to be the most highly predictable and reliably thrombogenic, although technically quite difficult. The tuck model produces clot analogous to that produced clinically and is easy to perform, although a predictable number of vessels will not thrombose. CONCLUSIONS: The results of this study comparing various animal models of anastomotic thrombosis suggests that the tuck model is the model of choice for most thrombus prevention studies. When predictability of thrombosis is a critical factor, the inversion graft model should be chosen.

Animals↗
PubMed1994

Head and neck neoplasms: magnetization transfer analysis.

PURPOSE: Magnetization transfer (MT) imaging enables analysis of the contribution of restricted motion protons in the macromolecular pool to magnetic resonance (MR) signal intensity. The authors undertook this study to determine whether MT ratios (MTRs) could be used to predict pathologic characteristics of head and neck neoplasms. MATERIALS AND METHODS: Fifty-four patients with pathologically proved neoplasms (squamous cell carcinomas, n = 33; non-squamous cell carcinomas, n = 11; benign masses, n = 10) underwent MT imaging. MTRs were correlated with pathologic findings. RESULTS: No statistically significant correlations were noted between MTRs and degree of differentiation, keratinization, cells per high-power field, and rate of mitosis. Statistically significant differences were found between MTRs of malignancies and muscle (P < .01), cerebrospinal fluid (P < .001), fat (P < .001), and benign neoplasms (P < .001). MTRs of muscle were higher than those of benign, squamous cell, and non-squamous cell neoplasms. CONCLUSION: MT imaging shows promise in differentiation of benign from malignant head and neck neoplasms. No statistically significant differences in MTRs were noted among malignancies.

Carcinoma, Squamous Cell↗
PubMed1994

MR of mandibular invasion in patients with oral and oropharyngeal malignant neoplasms.

PURPOSE: To investigate whether MR imaging is an accurate means of assessing mandibular invasion in patients with carcinoma. METHODS: We retrospectively studied the MR scans of 22 patients with pathologic or surgical confirmation of mandibular invasion from oral and oropharyngeal cancers. The MR images were blindly analyzed using primary criteria of: (a) cortical breakdown, (b) replacement of bone marrow fat, or (c) gadopentetate dimeglumine enhancement of a mass at the bone marrow defect. Secondary criteria of: (a) contiguous soft-tissue mass, and (b) mass on both sides of the mandibular cortex were also examined. Mandibular invasion was graded as periosteal/cortical, medullary, or no invasion. RESULTS: Primary positive findings of cortical breakdown and abnormal bone marrow signal were highly sensitive (100%) for periosteal/cortical invasion and medullary involvement, respectively. However, a high rate of false-positive studies hampered the MR accuracy, which fell into the 73% to 77% range. A negative MR study was highly predictive, but a positive study was less valuable. Gadolinium enhancement added little to the MR study's accuracy. False-positive studies mainly occurred in the setting of prior irradiation, osteoradionecrosis, and odontogenic infections. CONCLUSIONS: MR imaging is a sensitive method for detecting mandibular invasion but has a low positive predictive value. A negative study virtually excludes cortical/periosteal or bone marrow invasion.

Adipose Tissue↗
PubMed1994

The neurocutaneous free fibula flap in mandibular reconstruction.

Despite the delayed application of the free fibula flap to mandibular reconstruction, its recognition as a reliable, sensate skin paddle combined with enough bone to repair any mandibular defect and offer bicortical fixation of osseointegrated implants has proved the free fibula flap to be a "workhorse" in the repair of composite mandibular defects. The low donor site morbidity slightly eases the wait for the molecular reconstructive "cocktails" from the shelf of the next millennium.

Adult↗
PubMed1994

Free tissue transfer in oromandibular reconstruction. Necessity or extravagance?

The challenges of oromandibular reconstruction have spawned tremendous progress and controversy in recent years. Foremost has been the development of free-tissue transfer. The selection of autogenous composite grafts whose volume and features closely approximate those of the ablative defect seems attractive, but are free flaps for everybody? This article defines the goals of the elusive "ideal" oromandibular restorative technique and compares the numerous options available to today's surgeon.

Deglutition↗
PubMed1994

Options for reconstruction of the pharyngoesophageal defect.

Reconstruction of the circumferential pharyngoesophageal defect and functional rehabilitation of swallowing after cancer ablation remain a challenge for head and neck surgeons. A variety of techniques have been described, four of which have particular merit. The following general guidelines can be utilized when selecting a reconstructive technique. The pectoralis major myocutaneous flap can be used when pharyngeal mucosa remains following cancer resection or by surgeons who do not perform microvascular free tissue transfer to reconstruct circumferential defects. Gastric pull-up should be used if significant extension of tumor into the esophagus is present, oncologically necessitating esophagectomy. Free jejunal flaps are particularly useful in obese patients or patients in whom the lateral cutaneous thigh flap is otherwise contraindicated. The lateral thigh flap gives excellent results, has low morbidity, and causes virtually no functional impairment at the donor site. We believe that it represents state of the art in pharyngoesophageal reconstruction.

Esophageal Neoplasms↗
PubMed1994

Lateral thigh flap.

The lateral thigh flap is a fasciocutaneous flap from the lower limb that can be a versatile and reliable alternative in the reconstruction of specific head and neck defects. This article discusses the anatomy, clinical applications, advantages, and disadvantages of the lateral thigh flap.

Esophagus↗
PubMed1994

Free flap transfer for restoration of sensation and lubrication to the reconstructed oral cavity and pharynx.

The reconstruction of defects of the oral cavity and pharynx, whether created by trauma or by tumor ablation, begins with a careful assessment of the patient and the defect. Ideally, it ends with the successful execution of the reconstructive surgical procedure that optimally restores form and function to the patient. The modern head and neck reconstructive surgeon must be adept at performing all reconstructive options in order to objectively choose among the many grafts and flaps now available. This article attempts to guide the surgeon in selecting the most appropriate surgical tool to best restore defects of the oral cavity and pharynx.

Deglutition↗
PubMed1994

Postoperative monitoring and salvage of microvascular free flaps.

We believe that it is essential to closely monitor the viability of any free flap in order to decrease potential morbidity to the patient. A myriad of techniques have been described, many of which appear quite promising; none has been widely accepted. We believe that clinical assessment of an exposed portion of a free flap is the most reliable method of postoperative "surveillance"; however, continuous observation by the surgeon is impractical. Other monitoring techniques, such as laser-Doppler flowmetry, allow nursing personnel to observe the patient in order to alert the surgeon at the first sign of trouble. Adjunctive monitoring techniques are currently imperfect and, in general, expensive. The cost must be measured, however, against the potential loss of a flap and its subsequent consequences. Until an "ideal" monitoring technique becomes available, a combination of some of the techniques described here will enable the surgeon to maximize the chances of salvaging a failing flap.

Esophagus↗
PubMed1994

Magnetization transfer imaging of the head and neck: normative data.

PURPOSE: To determine magnetization transfer ratios for normal head and neck structures so that evaluation of disease will be possible. METHODS: Two-dimensional magnetization transfer imaging was performed in 12 healthy volunteers and 20 patients. We used a repetition time of 500, echo time of 12, 20 degrees flip angle, and a magnetization transfer pulse offset from the resonance frequency of water by 2000 Hz (pulse duration 19 milliseconds, waveform area approximately 10 times greater than that of a 90 degree pulse). Magnetization transfer ratios (1 - [intensity after suppression/intensity before suppression]) were calculated for normal structures. RESULTS: The magnetization transfer ratio of facial muscles (0.54) was equivalent to that of tongue muscles (0.54). These values exceeded those of parotid (0.39) and submandibular glands (0.41). Fat (0.07) and cerebrospinal fluid (0.05) had negligible transfer. CONCLUSION: Magnetization transfer imaging is a simple and effective means of studying the contribution of macromolecular protons to the MR image. Normal neck structures show a wide range of magnetization transfer rates, maximal for muscle and minimal for cerebrospinal fluid and fat.

Adult↗
PubMed1993

Pharmacologic manipulation of random skin flaps with pentoxifylline.

The literature demonstrates inconsistent results amongst investigators who have used pentoxifylline in an effort to enhance skin flap survival. This study employed a standardized skin flap model in the rat and a standard intraperitoneal dose of pentoxifylline (10 mg/kg) delivered in four different temporal regimens. Fluorescein staining and length of flap survival were measured. The only regimen that demonstrated increased flap survival over saline controls included administration of the drug immediately upon raising the flap and every 12 hours for the next 7 days. Three different regimens that included preoperative administration of the drug failed to demonstrate a beneficial effect on skin flap survival. Slight improvement in flap survival was seen in animals receiving fluorescein. These results suggest an inconsistent pentoxifylline effect even within a single controlled study.

Animals↗
PubMed1989

Thrombolysis with systemically administered t-PA in a new venous thrombosis model.

Early thrombosis of either the arterial or venous supply of a free flap or island pedicle flap results in total flap necrosis. Until very recently, the only option for flap salvage was surgical intervention and, often, revision of the vascular pedicle. Current advances in the pharmacologic treatment of coronary artery and deep leg vein thrombosis have kindled interest in the field of reconstructive surgery for pharmacologic treatment of thromboses that compromise flaps. In the past, there has been research on the local and systemic administration of thrombolytic agents for lysis of experimentally induced thrombi in various animal models. A new venous inversion graft thrombosis model is presented here, which possesses many advantages over previously employed research models. This study demonstrates thrombolysis with systemically administered tissue plasminogen activator (t-PA) in this model.

Animals↗
PubMed1988

Leeches. Objective monitoring of altered perfusion in congested flaps.

In plastic and reconstructive surgery, there has been new interest in the use of the medicinal leech (Hirudo medicinalis) for the treatment of venous congestion. To the best of our knowledge, no study has been performed to objectively demonstrate the benefits of leeching a congested flap. Doppler laser perfusion monitoring (DLPM) was used to record blood flow changes in pig rump flaps compromised by venous occlusion. With the application of leeches to nine congested pig rump flaps, significant increases in blood flow were demonstrated both clinically and by DLPM. It is concluded from this study that DLPM can demonstrate objective improvement in microcirculatory perfusion with leeching.

Animals↗