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Biomedical subjects

N L Schenck

Publications and source records attributed to N L Schenck.

17 recordsLinked to original sources
PubMed1977

Cementomas--aggressive or innocuous neoplasms?

No class of tumor is so inadequately discussed in the otolaryngology literature as the "cementomas". Until recent years, four distinctly different benign fibro-osseouslesions containing cementum were clumped together under the heading of cementoma. The separate entities in this tumor class are benign cementoblastoma (true cementoma), cementifying fibroma, peripical cemental dysplasia, and gigantiform cementoma (florid osseous dysplasia). Only an occasional case of the gigantiform variant or an unusually aggressive cementifying fibroma requires an extensive operation for complete excision.

Adolescent↗
PubMed1977

Frontal sinus trauma: experimental reconstruction with proplast.

Trauma has become the most common pathologic entity requiring operative intervention in the frontal sinus. Treatment has evolved from simple open drainage to ablation with reconstruction at a later date. Methyl-methacrylate, currently the most widely used alloplastic material, has inherent disadvantages such as two-stage reconstruction, difficulty in handling and molding, and susceptibility to trauma. The present investigation evaluates Proplast, a biocompatible Teflon fluorocarbon polymer implant, in one and two-stage frontal reconstruction following traumatic defects to the canine frontal sinus. Following the loss of anterior or posterior frontal bone, Proplast provided excellent cosmetic reconstruction over a period of one year. Resistance to infection was good, reaction with dura and brain was absent, and cerebrospinal fluid leaks sealed rapidly. In contrast to other alloplastic materials, rapid vascularization and collagen ingrowth lead to stabilization rather than sequestration. Several advantages over alloplastic and metallic implants may give Proplast a unique potential in operative cranioplasty.

Animals↗
PubMed1976

Experimental evaluation of a new implant material in frontal sinus obliteration: a preliminary report.

Frontal osteoplasty with exogenous material has been uniformly unsuccessful both experimentally and clinically. Our experiment was designed to test the long-term behavior of a new poly (tetrafluoroethylene)-carbon fiber implant material (Proplast) in a canine frontal sinus model. Varying conditions such as removal of the sinus mucoperiosteum, closure of the nasofrontal ducts, exposure of dura mater, and cerebrospinal fluid leaks were studied at intervals up to one year. Proplast was 100% successful in obliteration of the canine frontal sinus. The ultraporous nature allowed rapid vascularization, collagen ingrowth, and new bone formation, and led to stabilization rather than sequestration. Frontal obliteration with Proplast may be clinically superior to osteoplasty with any other presently available exogenous material or with osteoneogenesis alone, and may even obviate the few complications encountered with adipose implants. Only longer range experimental and clinical evaluation will provide the answer.

Animals↗
PubMed1976

An experimental model for the study of endolymphatic hydrops in sharks: implications for the clinician.

In recent years, attention has focused on the role of the endolymphatic sac (ELS) and the endolymphatic duct (ELD) in the pathogenesis of endolymphatic hydrops (ELH). Changes have been noted surgically and radiographically by others in the ELS and ELD in patients with ELH. This report summarizes the development of a shark model with which to study the pathophysiology of ELH. The background material and overall results of anatomic, histopathologic, and ultrastructural studies using the model are presented. Possible implications for the clinical handling of ELH as a result of this work is emphasized.

Animals↗
PubMed1976

Frontal sinus disease. IV. Cellular response to experimentally-induced infection.

The pathogenesis of chronic frontal sinusitis is poorly understood. The canine frontal sinus model was developed to isolate experimentally the variables involved. We have recently determined that blockage of the naso-frontal duct does not, by itself, produce sinusitis or mucocele experimentally. The purpose of the present investigation is to examine the histological and ultrastructural responses of the sinus mucosa to artificially-induced infection. Bone wax was implanted in the canine frontal sinus via an osteoplastic flap, and subsequently removed three months later. Radiological, histological and ultrastructural analysis of the resultant infected mucosa was performed at periods up to one year. The sinus mucosa did not return to normal up to nine months following removal of the infection-inciting foreign body. Persistent changes included epithelial and submucosal thickening, polypoid degeneration, matting of the ciliary carpet, and "bursting" of the ciliary cell bodies. In the light of this and previous experiments, an insidious cycle of events leading to irreversible frontal sinus disease is postulated, requiring the interplay of at least three variables: the infectious insults, the response of the sinus mucosa, and the variable patency of the nasofrontal duct.

Disease Models, Animal↗
PubMed1975

Frontal sinus disease. III. Experimental and clinical factors in failure of the frontal osteoplastic operation.

The surgical approach to frontal sinus disease has been subject to much variation. Experimental evidence for new treatment modalities is quite limited. Frontal osteoplasty, while probably the best procedure to date, has up to a 25 percent failure rate. Possible complications include recurrent disease, incomplete bony obliteration (Macbeth technique), infection of the adipose implant, frontal bossing or depression, and laceration of the dura. Four experimental groups were designed using the canine frontal sinus model. Results indicated that stripping the mucosa in a normal sinus with intact periosteum and a patent nasofrontal duct will not consistently lead to normal mucosal regeneration. Second, the additional factor of removing the periosteum (as in osteoplasty by osteoneogenesis), leads to partial fibrous obliteration complicated by mucocele formation. Third, sinus obliteration by osteoneogenesis was much more consistent with concurrent closure of the nasofrontal duct. Fourth, intentionally leaving a strip of mucosa leads to failure of obliteration by osteoneogenesis 100 percent of the time. Finally, bony-fibrous obliteration increases with time but is still incomplete after one year. In light of these results, fat obliteration with closure of the nasofrontal duct is probably more reliable than obliteration by osteoneogenesis.

Adipose Tissue↗
PubMedDate not supplied

Local anesthesia in otolaryngology. A re-evaluation.

Almost a half century following attempts to ban its use, cocaine remains at the pinnacle of topical anesthesia in otolaryngology. To understand how nonaddicting synthetic substitutes such as procaine, dibucaine, tetracaine and lidocaine have not totally supplanted cocaine, requires an in-depth analysis of its unique pharmological properties, untoward effects and potential substitutes. Almost all of the reported cocaine deaths occurred after subcutaneous injection; when used topically, cocaine's toxicity has been confined to an occasional reaction. Certain variables under physician control may be manipulated to reduce the chance of reaction to a minimum. For example, intermittent application of a particular dosage results in lower blood levels, and allowing sufficient time between doses reduces the amount necessary to obtain the desired anesthesia. If total dosage is kept below 200 mg there are few reactions. A singular advantage of cocaine over other topical anesthetics is its inherent ability to cause vasoconstriction, thus retarding its own absorption. The addition of a topical vasoconstrictor such as epinephrine is thus redundant, and may actually be harmful as cocaine sensitizes the patient to exogenous epinephrine. Finally, the usual preoperative dosages of barbiturates are entirely inadequate to prevent or treat cocaine reactions. Why, then, have synthetic local anesthetics not replaced cocaine? Inherent differences in topical effectiveness, duration of anesthesia and toxicity provide the answer. Of other local anesthetics possessing topical effectiveness tetracaine is about six times more toxic than cocaine. Dibucaine is as toxic as tetracaine, and lidocaine, while relatively nontoxic, provides only a 15 minute duration of topical anesthesia. A review of cocaine and its potential substitutes thus leads to the conclusion that cocaine is still a vital and necessary instrument in the otolaryngologist's armamentarium, singularly providing excellent topical anesthesia of usable duration, vasoconstriction, and shrinkage of mucous membranes, all with a quite acceptable margin of safety.

Administration, Topical↗
PubMedDate not supplied

Airway intervention in croup and epiglottitis: the changing role of the otolaryngologist.

Recent evidence indicates that endotracheal intubation is supplanting tracheostomy for the short-term treatment of airway obstruction in epiglottitis and croup. Care should be provided by a triumvirate of physicians to include and otolaryngologist, a pediatrician, and an anesthesiologist. Intensive care facilities are also a prerequisite. Standard tracheostomy should be considered in cases requiring intubation longer than 72 hours.

Child↗
PubMedDate not supplied

Tetracaine.

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Anesthesia, Local↗