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Biomedical subjects

S D Schaefer

Publications and source records attributed to S D Schaefer.

At least 19 recordsLinked to original sources
PubMed2001

Modern concepts of frontal sinus surgery.

OBJECTIVES/HYPOTHESIS: To validate the endonasal surgical approach to frontal sinus in inflammatory sinus disease, trauma, and selective tumor surgery, and to define the role of external approaches to the frontal sinus. Endonasal frontal sinusotomy can range from endoscopic removal of obstructing frontal recess cells or uncinate process to the more complex unilateral or bilateral removal of the frontal sinus floor as described in the Draf II-III drainage procedures. In contrast, the osteoplastic frontal sinusotomy remains the "gold standard" for external approaches to frontal sinus disease. METHODS: A retrospective review of 1286 patients undergoing either endonasal or external frontal sinusotomy by the authors at four university teaching programs from 1977. Prior author reports were updated and previously unreported patient series were combined. RESULTS: Six hundred thirty-five patients underwent type I frontal sinusotomy, 312 type II sinusotomy, and 156 type III sinusotomy. A successful result was seen in these groups, 85.2% to 99.3%, 79% to 93.3%, and 91.5% to 95%, respectively. External frontal sinusotomy or osteoplastic frontal sinusotomy was successfully performed in 187 of 194 patients. Clinical symptoms, endoscopic findings, computed tomography, and magnetic resonance image scanning, and reoperation rate measured postoperative success. CONCLUSIONS: A stepwise approach to the surgical treatment of frontal sinusitis, trauma, and selective benign tumors yields successful results as defined by specific criteria which vary from 79% to 97.8%. The details of specific techniques are discussed, essential points emphasized, and author variations noted.

Chronic Disease↗
PubMed2000

Extradural extranasal combined transmaxillary transsphenoidal approach to the cavernous sinus: a minimally invasive microsurgical model.

UNLABELLED: The authors have previously described an extradural transmaxillary approach to the anterior compartment of the cavernous sinus. In an effort to expand the surgical access to that area without necessitating a craniotomy or wide transfacial dissection, they present a modification of the transmaxillary approach to the sellar region and cavernous sinus. METHODS: The approach was developed on 12 fresh and 12 embalmed cadaveric specimen, and 2 dry skulls. The initial sublabial incision is followed by a maxillotomy to expose the course of the infraorbital nerve (terminal branch of maxillary branch of the trigeminal nerve) on the roof of the maxillary sinus. The route of the infraorbital nerve is traced to the pterygopalatine fossa as a guide to the foramen rotundum. Superomedial drilling of the foramen rotundum is then performed to reveal the contents of the superior orbital fissure. After the nerves are safely identified in the superior orbital fissure, medial enlargement of the window into the cavernous sinus is made possible by drilling the lateral and posterior wall and septum of the sphenoid sinus. RESULTS: The combined transmaxillary transsphenoidal approach offers an excellent exposure of the sellar and infrasellar region. The approach offers clear visualization of the ipsilateral loop of the carotid artery, the pituitary fossa, and the cranial nerves of the ipsilateral cavernous sinus. Mean operative reach is 38 mm from the posterior wall of the maxillary sinus to the ipsilateral carotid loop and 56 mm to the contralateral loop. The width of the operative window is 26 mm at the base within the cavernous sinus. CONCLUSION: The model offers a minimally invasive approach that avoids the need for craniotomy or violating the nasal cavity. It may be safely employed to access vascular as well as invasive lesions of the sellar and infrasellar region. The approach offers excellent visualization of the ipsilateral intracavernous carotid artery with both proximal and distal control, as well as cranial nerves III, IV, VI, V2, the hypophyseal region, and the medial aspect of the contralateral cavernous sinus.

Cavernous Sinus↗
PubMed1999

Approaches to the sellar and parasellar region: anatomic comparison of the microscope versus endoscope.

OBJECTIVE: Traditionally, surgical approaches to the sellar region require the use of the operating microscope. Over the past decade endoscopic surgery has gained much popularity because of advances in optics and illumination. Endoscopic surgery of the sellar region has been performed successfully. The goal of the present study was to quantify the amount of exposure to the sellar and suprasellar region that the endoscope provides versus the microscope, with three different anterior approaches to the sellar region. METHODS: The transethmoidal, endonasal-transsphenoidal, and sublabial-transsphenoidal approaches were performed on 14 formalin-fixed cadaver heads with a 0 degrees endoscope and repeated with the operative microscope. The distances of relevant surgical landmarks and the amount of exposure superior and anterior to the dorsum sella, as well as the lateral exposure, were measured. The mean distances were then used to calculate the volume of exposure for each of the approaches. RESULTS: It was found that the endoscope provided greater view than the operating microscope in all three approaches. The difference was statistically significant using a paired Student t test and a signed-rank test (P<.001). CONCLUSION: The authors believe that endoscopic surgery of the sellar region can be performed safely and effectively, while providing the surgeon with a view that is superior to that afforded by the operating microscope.

Cadaver↗
PubMed1998

An anatomic approach to endoscopic intranasal ethmoidectomy.

OBJECTIVES: To develop an anatomic and functionally based approach to endoscopic intranasal ethmoidectomy. To develop such an approach using the salient features of the anterior to posterior (AP) and posterior to anterior (PA) intranasal sinus operations. To assess the safety of this form of ethmoidectomy in a patient population. STUDY DESIGN: Retrospective chart review of patients undergoing ethmoidectomy by author or by residents under his direct supervision. SETTING: University teaching hospital. In the 509 patients meeting study criteria, 168 anterior ethmoidectomies, 586 total ethmoidectomies, 264 sphenoidotomies, 290 frontal sinusotomies, and 838 antrostomies were performed between April 1992 and August 1997. RESULTS: A complication rate of 0.98% and revision rate 2.9% were observed. CONCLUSIONS: Combining an AP approach to conserve sinus anatomy with a PA approach to avoid surgery directed toward the skull base provides a functional and safe procedure as demonstrated by the reported results.

Acute Disease↗
PubMed1995

Statistical analyses of electromyographic activity in spasmodic dysphonic and normal control subjects.

Heterogeneity in the quality and task sensitivity of vocal symptoms in the spasmodic dysphonia (SD) population contributes to controversy as to whether this is a single disorder or two disorders with different etiologies (neurogenic versus psychogenic). Perceptual and acoustic assessments of vocal symptoms are inadequate to resolve this controversy. However, myoelectric events are intimately proximal to the source of vocal disruption and may be informative. The present report employs statistical modeling of quantitative amplitude measures of electromyographic activity recorded from thyroarytenoid to examine neuromotor bases of vocal symptoms in SD. Consideration of perceptual ratings of the quality and task sensitivity of vocal symptoms in the context of statistical models provides support for the conclusion that the range of vocal symptoms identified as SD represents a single, neurogenic disorder.

Adult↗
PubMed1995

Time-frequency analyses of thyroarytenoid myoelectric activity in normal and spasmodic dysphonia subjects.

Digital recordings of thyroarytenoid (TA) myoelectric activity (via percutaneous hooked-wire electrodes) were obtained for 10 normal control subjects and 10 subjects with spasmodic dysphonia during performance of five tasks of varying complexity: quiet breathing, Valsalva maneuver, whispered /i/, voiced /i/, and "beep beep went the heap." Time-frequency power spectral density functions, PSD(f,t), were determined for a selected segment of the signals, and measures of median frequency, mean frequency, bandwidth, and center frequency of PSD(f,t) were derived for each sample point. Statistical median, mean, standard deviation, minimum, maximum, and mode of the power spectral density measures were computed to compose feature vectors for each TA myoelectric recording. Statistical pattern recognition procedures using maximum likelihood classification tests were applied to the feature space to discriminate disordered from normal speakers for each task. Findings indicate a high level of discriminability between subject groups for phonated speaking tasks in contrast to low levels of discriminability for whispered and nonspeech tasks. Graphical presentations of three-dimensional PSD(f,t) plots are given that illustrate changes in spectral characteristics of TA EMG at the onset of laryngospasm.

Adult↗
PubMed1993

Role of fine-needle aspiration in the evaluation of neck masses.

Fine-needle aspiration has assumed a large role in the evaluation of head and neck masses. It has been found to be simple, quick, accurate, and cost-effective in the workup of patients with unknown head and neck masses. This article reviews these advantages and the role of fine-needle aspiration in the evaluation of head and neck masses.

Algorithms↗
PubMed1993

Evidence of IgE-mediated hypersensitivity in allergic fungal sinusitis.

Despite documentation of specific immunologic hypersensitivity in a few case reports, controversy continues as to the role of allergy versus true infection in the clinical entity of allergic fungal sinusitis (AFS). Using a modified radioallergosorbent test (RAST) to multiple fungal antigens, 16 patients meeting the histologic criteria of AFS and with positive fungal cultures were compared to 5 control patients with similar preoperative clinical findings but without histologic or culture evidence of AFS. All patients were immunocompetent and none demonstrated histologic evidence of tissue invasion. All AFS patients were RAST-positive to at least one fungal antigen in the family of their cultured organism with positive defined as class 2 or greater. No control patient was RAST-positive to either dematiaceous or Aspergillus fungal antigens. Thus, modified RAST testing can aid in the routine clinical diagnosis of AFS, and it provides further serologic evidence for a type I hypersensitivity in the pathogenesis of AFS.

Adolescent↗
PubMed1993

Inflammatory diseases of the sinuses:anatomy.

Inflammatory sinus disease most commonly results from or is exacerbated by areas of obstruction within the sinuses. Recent revision of our understanding of mucociliary clearance has placed a renewed emphasis on sinus anatomy, particularly in identifying natural sinus ostia. A discussion of paranasal sinus anatomy is presented in this article along with special reference to these areas as well as contiguous sites that may be involved as a complication of inflammatory disease.

Female↗
PubMed1992

The acute management of external laryngeal trauma. A 27-year experience.

The acute care of 139 consecutive patients with external laryngeal trauma over a 27-year period is reported. This article represents an effort to periodically reevaluate our care of this relatively infrequent injury and to share our changes and refinements in treatment. This series provides the means to test and establish basic principles in the acute care of external laryngeal trauma because (1) the number of years encompassed by the article, (2) most patients were managed by one physician, (3) the relative consistency of management principles throughout the series, and (4) the delivery of trauma care in Dallas County, Texas, reflects a broad sampling of this injury within the geographic area.

Biomechanical Phenomena↗
PubMed1992

Multichannel electromyographic observations in spasmodic dysphonia patients and normal control subjects.

Spasmodic dysphonia is primarily a disorder of vocalization. Increasing evidence, however, suggests that individuals with this disorder comprise a heterogeneous population characterized by abnormal motor control throughout the vocal tract. Multichannel simultaneous electromyography was performed on 11 spasmodic dysphonia patients and 10 normal awake subjects to investigate both the distribution of neuromotor abnormality within the vocal tract (eg, intrinsic and extrinsic laryngeal muscles, tongue, and palate) and the contribution of activation of higher central nervous system centers to observed abnormality. Experimental tasks ranged from vegetative (quiet breathing) to simple linguistic (short sentences). Digitized electromyographic signals were analyzed to compute the amplitude envelope and extract a set of parameters that represent amplitude characteristics. Electrode insertions were cross-validated by quantitative analysis of patterns of activation across selected reference tasks and by traditional qualitative methods. Between-group differences were found for measures of normalized median and peak token amplitudes. These differences are both task- and measure-dependent. Results highlight the complex and interactive effects of muscle, task, and quantitative measures on between-group differences.

Adult↗
PubMed1991

Heterogeneity in spasmodic dysphonia. Neurologic and voice findings.

Spasmodic dysphonia is a disturbance of phonation with laryngeal spasms. We report voice and neurologic examination findings in 45 subjects. Neurologic abnormalities were found in 32 subjects (71.1%). Rapid alternating movement abnormalities, weakness, and tremor were common. Incoordination and spasticity were rare. Lower extremity findings were frequent. Abnormalities were bilateral. Spasmodic dysphonia severity was related to age. Type, severity, and duration of vocal symptoms were not different for subjects with or without neurologic abnormalities. Vocal tremor was more frequent in neurologically abnormal subjects. Involvement of a pallidothalamic-supplementary motor area system could account for neurologic findings, brain imaging findings, and clinical heterogeneity. The view emerging is that spasmodic dysphonia is a manifestation of disordered motor control involving systems of neurons rather than single anatomical sites.

Adult↗
PubMed1991

The treatment of acute external laryngeal injuries. 'State of the art'.

Guidelines are presented for the management of acute external laryngeal trauma based on personal experience and basic principles evolved over the past two decades. Accurate assessment of the extent of injury has permitted stratification of treatment ranging from observation to open reduction and internal fixation of the laryngeal skeleton. Results are often predictable and frequently lead to restoration of the voice and airway.

Diagnosis↗