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Biomedical subjects

R C Lindeman

Publications and source records attributed to R C Lindeman.

At least 37 records · Page 2Linked to original sources

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↗

Middle ear fluid.

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Body Fluids↗

Indications for the tracheoesophageal diversion procedure and the laryngotracheal separation procedure.

Impaired protective function of the larynx can lead to intractable aspiration, a severe and potentially fatal disorder. If medical therapy fails to prevent intractable aspiration, surgical separation of the upper respiratory tract from the digestive tract is necessary to prevent recurrent contamination of the respiratory system in these patients. Two such surgical procedures are the tracheoesophageal diversion procedure and the laryngotracheal separation procedure. Our approach to patients with intractable aspiration and the indications for the use of these surgical procedures for the prevention of aspiration are discussed.

Esophagus↗