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Biomedical subjects

R C Lindeman

Publications and source records attributed to R C Lindeman.

At least 19 recordsLinked to original sources

Ceravital versus plastipore in tympanoplasty: a randomized prospective trial.

The hearing results and extrusion rates for ossicular chain reconstruction using a new material called Ceravital, a bioactive glass ceramic, were compared with those for Plastipore, a porous polyethylene that is our standard for synthetic materials. Our null hypothesis was that the results of the two materials were similar. A Ceravital or a Plastipore prosthesis was randomly assigned to 112 consecutive patients. We had 6-month follow-up on 100 patients and 3-year follow-up on 80 patients. The average air-bone gap at 4,000 Hz was 6 dB less with Plastipore than with Ceravital (p = .036). Patients were twice as likely to have an air-bone gap of 15 dB or less with Plastipore than with Ceravital (40% versus 21%; p = .061). Two of the 38 patients with Ceravital prostheses had a late hearing-result failure due to resorption of the prosthesis material. The materials had similar extrusion rates. We rejected our null hypothesis. The Plastipore group had better hearing results than did the Ceravital group.

Analysis of Variance

The tracheoesophageal diversion and laryngotracheal separation procedures for treatment of intractable aspiration.

Intractable aspiration is a severe and often fatal complication in patients with impaired protective function of the larynx. This problem is usually a result of central nervous system disorders such as cerebrovascular accident, trauma, neoplasms, or degenerative disease. Surgical separation of the upper respiratory tract from the digestive tract can prevent recurrent contamination of the respiratory system in these patients. Two such procedures are the tracheoesophageal diversion procedure and a modification of this operation, the laryngotracheal separation procedure. The Virginia Mason Medical Center experience with these procedures, their indications, technique, and outcome are presented. In addition, cases of successful surgical reversal of the diversion procedures are discussed.

Adult

Discriminative phonation in macaques: effects of anterior mesial cortex damage.

Lesion damage of the anterior midline hemisphere in M. mulatta results in impaired discriminative vocal activity. Destruction of the supplementary motor area (SMA) or pre-SMA greatly increases vocal response latency without similar changes in a non-vocal response. Discrimination and efficiency in performing the vocal and non-vocal responses are unaffected by this damage. The behavioral deficit reflects a specific loss in initiating vocal signals.

Animals

Acute labyrinthine disorders.

A patient seeking emergency treatment for a labyrinthine disorder is usually complaining of dizziness. The task at hand in the emergency room is, first, to rule out the truly life threatening emergent disorders, and then by means of a rapid but adequate history and physical examination to aid in the differentiation between central and peripheral etiologies. If the problem is central, and especially if there are signs of a true emergency, there should be no hesitation in sharing the responsibility for the care of this patient with a neurologist or neurosurgeon. If one is convinced that the problem is of a peripheral etiology, one most likely is dealing with Meniere's disease, vestibular neuronitis, benign paroxysmal positional vertigo, or true labyrinthitis. An acoustic tumor must always be considered. Appropriate laboratory and x-ray studies may be initiated and therapy begun. Although the emergency room evaluation can be inclusive and accurate, it is necessarily incomplete. There is no substitute for a more thorough history and physical examination under more relaxed conditions, complete audiometry, electronystagmography, polytomography, myelography, angiography, or whatever additional sophisticated studies are deemed necessary. If performed well, however, the emergency room encounter forms an invaluable foundation upon which further diagnostic and treatment decisions are based.

Acute Disease

Temporal bone trauma and facial paralysis.

Temporal bone trauma includes a wide range of injuries of greater and lesser severity, most of which require the immediate attention of an otolaryngologist. The most common temporal bone injuries encountered in an emergency room setting include longitudinal and transverse fractures of the temporal bone with and without facial paralysis, labyrinthine concussion, foreign bodies in the external canal, penetrating injuries via the external auditory canal, and pressure injuries, including otitic barotrauma, water skiing accidents, blows or slaps to the ear or side of the head, and severe impact noise. A brief but inclusive examination can be performed within the limitations necessarily imposed by an emergency room setting. Cranial nerve screening, balance testing, hearing, and vestibular evaluation can be accomplished with a considerable degree of accuracy. To a large extent, the long term result reflects the quality of the initial examination.

Barotrauma

Cerebellar regulation of phonation in rhesus monkey (Macaca mulatta).

Five rhesus monkeys (Macaca mulatta) were trained to emit a "coo" vocalization with a duration of at least 500 msec. After stable performance was achieved cerebellar lesions were introduced, and various pre- and postlesion measures of phonation and of laryngeal EMG activity were compared to assess the effects of the lesions. The phonatory changes were interpreted with respect to possible laryngeal or respiratory modifications. The relation between fundamental frequency and intensity of phonation was changed in some animals, with no obvious alterations in either fundamental frequency or intensity considered separately. Intensity of phonation was decreased while duration was prolonged in two animals. Fundamental frequency of phonation was also affected in some animals. Reliable laryngeal EMG was obtained in two animals and was affected by cerebellar lesions. These results indicate that normal cerebellar function is involved in the control of fundamental frequency, intensity, duration, and the coordination of the laryngeal and respiratory systems for the control of phonation.

Acoustics

Tracheo-esophageal anastomosis in treatment of chronic aspiration pneumonitis.

A patient underwent tracheo-esophageal anastomosis following repeated episodes of aspiration pneumonia after the resection of a meningioma at foramen magnum. The surgery eliminated the intractable problem with aspiration. This procedure is reversible, and restoration of the laryngeal function can be accomplished when the patient has recovered neurologically. If adequate neurologic recovery does not occur, the anastomosis can be left intact indefinitely.

Brain Neoplasms

Prolonged apnea in infant monkeys resulting from stimulation of superior laryngeal nerve.

We measured characteristics of apnea resulting from electrical stimulation of the superior laryngeal nerve (SLN) in 28 anesthetized infant monkeys ranging from a gestational age of 141 days to 49 days postterm and in four adult monkeys. Progressive reduction in ventilation accompanied weak suprathreshold SLN stimulation. Poststimulus apnea followed stronger stimulation. Apnea duration was directly proportional to stimulus duration, provided that stimulus intensity was at least 1.5 X threshold. Poststimulus apnea periods were briefer in older infants and did not occur in adults. Pao2 measurements in four animals showed that lower values were associated with the longer poststimulus apnea episodes. Upper airway resistance measurements obtained from a subglottal cannula revealed that glottal closure was transiently associated with the onset of SLN stimulation, but the degree of closure diminished during the course of stimulation and was not present during the subsequent period of apnea. The parameters of SLN stimulation determine specific changes in cardiovascular functions independently of their respiratory effects. The results suggest that a brief afferent input from the SLN may have prolonged effects on respiratory regulation in infants. These persisting effects may be an important consideration in sudden infant death syndrome mechanisms.

Airway Resistance

Muscle spindles in nonhuman primate extrinsic auricular muscles.

Muscle spindles were sought in peri-auricular muscles of several primate species (rhesus monkey, woolly monkey, and baboon). Transverse sections cut at 10 mu and stained primarily by a silver impregnation technique were examined using light microscopy. Spindles were identified on the basis of standard criteria. Posterior and/or superior auricular muscles of each species were found to contain spindles. At least some muscles innervated by facial nerve have classical spindles as component structures.

Animals

Infant primate larynx: developmental histology.

Laryngeal epithelium of monkeys (M. mulatta, M. nemestrina) ranging in age from late fetal to adult was found to undergo the following developmental changes: (1) progressive elaboration of commissural epithelium prenatally, reaching the adult form of pseudostratified columnar ciliated epithelium early in the postnatal period;(2) vocal process epithelium changing from cuboid to stratified squamous tissue during the late prenatal period, and (3) progressive increments in overall epithelial thicknees during development, reaching a maximum in the early postnatal period. Chondrocyte density of the cricoid and thyroid cartilage decreased during the late prenatal period, reaching the adult form at the neonatal stage. The evidence suggests that mechanical or metaplastic stresses do not determine the observed tissue changes.

Age Factors

Sudden death in infant primates from induced laryngeal occlusion.

Thirteen infant and juvenile monkeys and baboons were studied in procedures designed to assess the functional characteristics of the upper airway, with special attention to the consequences of laryngeal nerve stimulation. In young animals, stimulation of the recurrent laryngeal nerve produced closure of the airway in sufficient degree and duration to cause death. Older juvenile monkeys were resistant to fatal laryngospasm induced by nerve stimulation. A variety of patterns of general autonomic response accompanied the airway changes. These results are consistent with (1) a laryngospasm hypothesis to account for certain terminal events in sudden infant death syndrome, and (2) prior observations of age-related general autonomic stability.

Age Factors

Dimensions of the infant monkey upper airway.

Upper airways of infant Macaque monkeys were measured with respect to twenty-one dimensions of endocasts. Measurements were tabulated and plotted against age and body weight. Dimensions of the upper airway of these animals are characterized by variability.

Age Factors

Diverting the paralyzed larynx: a reversible procedure for intractable aspiration.

Some unfortunate patients suffer disorders which in one way or another, usually neurologically, severely restrict the larynx in its role as a protector of the lower airway. Aspiration ensues, and unless it can be successfully managed, repeated episodes of a violent pneumonitis may lead to terminal chest problems. In some patients, even the cuffed tracheostomy tubes of new and improved design do not adequately prevent aspiration over an extended time intervel, as evidenced by repeated bouts of aspiration pneumonia despite these cuffed tubes and despite optimal intensive care. For these patients with intractable aspiration, and in whom recovery is expected only after a prolonged period of time, we have suggested a diverting procedure which employs a tracheo-esophageal anastomosis, as an effective yet reversible solution. Such an anastomosis with concomitant tracheostomy allows aspiration of saliva and even food to occur through the malfunctioning larynx but diverts it back into the esophagus through the tracheo-esophageal anastomosis. In normal mongrel dogs we demonstrated that an end-to-side tracheo-esophageal anastomosis is well tolerated and can be performed without damage to the intrinsic larynx or recurrent laryngeal nerves. The tracheo-esophageal lumen remained patent and the anastomosis intact for as long as these animals were observed prior to reconstruction. The reversibility of the tracheo-esophageal anastomosis was demonstrated in these dogs by excising the anastomosis, repairing the esophageal defect, and restoring the continuity of the trachea by end-to-end anastomosis. Vocal cord motion remained intact, the dogs ate normally, and barked once again. A tracheo-esophageal anastomosis was performed in a 60-year-old white female who had suffered lower cranial nerve damage as a result of a large acoustic tumor and the excision thereof. Despite every effort to control aspiration, pneumonitis occurred and became fulminant. The diverting tracheo-esophageal anastomosis was performed with relative ease and was well tolerated by the patient. Aspiration was totally and dependably controlled, and no further chest complications occurred. Her nasogastric feeding tube was removed, and she ate a regular diet with very little difficulty. She gained in strength, became much more alert mentally, and is now taking care of herself in a nursing home. We are following her progress by indirect laryngoscopy and barium swallow examinations and at five months post anastomosis, we are possibly seeing the first signs of lower cranial nerve recovery. We hope that reconstruction and restoration of function will soon be possible.

Animals