Biomedical subjects
Publications and source records attributed to F B Simmons.
A change in fluid pressure in one intracochlear compartment also causes a pressure gradient in the other. Thus, one membrane break is likely to cause a secondary break. We have presented indirect evidence for such double membrane breaks in sudden hearing loss, and argue that one of the two breaks can heal spontaneously while the other remains active.
In 22 children (11 boys and 11 girls), aged 9 to 13 years, respiration was monitored during one night of sleep. No child had a significant history of breathing problems during sleep. Sleep was recorded using standard techniques (electroencephalography, electrooculography, electromyography), and respiration was measured with nasal thermistors and abdominal or thoracic strain gauges. Respiratory pauses (five seconds or longer) were determined for all sleep stages. Respiratory rate was scored only in the first and last sleep cycles and during ten waking minutes before sleep onset. Respiratory rate was significantly affected by wakefulness or stage of sleep: highest in wakefulness and stage 1, lowest in stage 2 of the last sleep cycle. Regularity of respiratory rate showed a similar effect. Variance of respiratory rate was significantly lower in girls than boys. Respiratory pauses during sleep were seen in every child, ranging from 3 to 40 pauses per night (average, 17.2 for boys and 18.0 for girls). Significantly greater numbers of pauses per minute were seen in stage 1 and rapid eye movement (REM) sleep than in stages 2, 3 and 4. The longest respiratory pause was 25 seconds. The conclusion is made that a small number of respiratory pauses during sleep are normal in children of this age.
Cardiac arrhythmias during wakefulness and sleep in 15 patients with sleep-induced obstructive apnea, and the effect of atropine and tracheostomy on these arrhythmias were studied by continuous overnight Holter electrocardiographic, respiratory and electroencephalographic recordings. Sleep was characterized by marked sinus arrhythmia in 14, extreme sinus bradycardia ( less than 30 beats/minute) in six, asystole of 2.5 to 6.3 seconds in five, second degree atrioventricular (A-V) block in two, and ventricular arrhythmias--complex premature ventricular beats in 10 and ventricular tachycardia in two. Arrhythmias during wakefulness were limited to premature ventricular beats in six. Atropine administration was partially and tracheostomy highly effective in preventing the majority of these arrhythmias during sleep. Marked sinus arrhythmia during sleep is characteristic of the syndrome of obstructive sleep apnea and is frequently accompanied by potentially life-threatening tachy- and bradyarrhythmias. Possible mechanism of production of these arrhythmias, the mode of action of tracheostomy and atropine, and the probable role of similar arrhythmias in the sudden infant death syndrome are discussed.
Anatomical or physiological airway obstructions during sleep, of which the patient is unaware, cause daytime sleepiness at first, then signs of decreasing mental function, and eventually in some individuals, pulmonary and systemic hypertension. A few of these patients had been recognized before, the Pickwickian syndrome and in children with cardiac problems and large tonsils. The majority, however, present as sleep disorders. This paper describes our surgical experience with improving the airways of 19 children and adults with daytime somnolence.
A sleep apnea syndrome due to upper airway obstruction was diagnosed in 25 adult men (25 to 65 years of age) using nocturnal polygraphic monitoring. Excessive daytime somnolence, hypnagogic hallucinations, and automatic behavior, personality changes with abnormal behavioral outbursts, impotence, morning headaches, abnormal motor activity during sleep, nocturnal enuresis, and high blood pressure should suggest this diagnosis when any of the symptoms are associated with loud snoring. Respiratory monitoring during sleep and nocturnal cardiovascular evaluation bring prognostic information and indications for therapy. Three types of therapeutic trials, namely, diet, medications with or without diet, and surgery have been performed. Only surgery has been beneficial in these cases.
The high and low frequency characteristics of clinically used electronystagmography (ENG) machines were evaluated using a "dummy patient" calibration source. About one half of the machines yielded tracings that were either seriously divergent from specifications or that otherwise inaccurately reproduced the calibration wave form. Some of these differences do affect the accuracy and quality of clinical recordings.
Explore the source record for details and available documents.
Histological comparisons have been made of predicted temporal-muscle flaps with and without an intact nerve supply. The viability of the musculoplasty depends on maintenance of the neural bundle.
Twelve patients with predominantly obstructive type sleep apnea underwent cardiac catheterization, hemodynamic monitoring, and arterial blood gas analysis during wakefulness and sleep. Abnormalities during wakefulness included systemic hypertension in four of 12, exercise-induced mild pulmonary hypertension in five of 12, and alveolar hypoventilation in one. During sleep nine patients had cyclic elevations of arterial pressure with each apneic episode, exceeding 200 mm Hg systolic in three of 12. Pulmonary artery pressures increased in 10 of 12, exceeding 60 mm Hg systolic in five. Marked degrees of hypoxemia (arterial P02, less than 50 mm Hg in eight of 12) and moderate hypercapnia with respiratory acidosis were associated with these hemodynamic changes. Cyclic upper airway obstruction during sleep may result in hypercapnia, acidosis, and pronounced hypoxemia, which can lead to hemodynamic abnormalities during sleep. Sustained pulmonary hypertension and possibly systemic hypertension may follow. Tracheostomy is an effective therapy and is recommended to symptomatic patients who have predominantly obstructive apnea but no relievable anatomic cause of upper airway obstruction.
Eight children, 5 to 14 years of age, were diagnosed by means of nocturnal polygraphic monitoring with a sleep apnea syndrome similar to that seen in adults. Excessive daytime sleepiness, decrease in school performance, abnormal daytime behavior, recent enuresis, morning headache, abnormal weight, and progressive development of hypertension should suggest the possibility of a sleep apnea syndrome when any of these symptoms is associated with loud snoring interrupted by pauses during sleep. Surgery may eliminate the clinical symptomatology.
There have been conflicting statements made in the literature on electronystagmograms (ENG) concerning the direction of beating of spontaneous nystagmus in the presence of a damaged labyrinth. This report presents a retrospective examination of 1,220 ENGs done at Stanford over the past four years with regard to the direction of spontaneous nystagmus and the side of the diseased labyrinth. The diseased labyrinth is indicated by a hypoactive caloric response. The study showed that one cannot predict the side of the labyrinthine lesion from the direction of beating of the spontaneous nystagmus.
Explore the source record for details and available documents.
The computer-averaged N1 response from humans to click stimuli was compared at three recording sites -- dermal and subdermal electrodes in the ear canal, and a transtympanic electrode on the promontory. A total of 26 subjects, some of whom were measured at all three sites, participated in 47 experiments. The promontory electrodes were consistently more sensitive and yielded cleaner N1 waveforms than did the ear canal sites. In considering the clinical use of N1 averaging, the advantages of the transtympanic method outweigh the risks. While a few persons yield reasonable good ear canal potentials, the reliablitity of this method in general application is inadequate and unpredictable.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.