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Biomedical subjects

M Hirshkowitz

Publications and source records attributed to M Hirshkowitz.

At least 19 recordsLinked to original sources
PubMed1996

Sleep-related erectile activity.

Sleep-related erections occur in all healthy, potent men in close temporal association with REM sleep. These erections are naturally occurring and can be assessed quantitatively. The nocturnal tumescence cycle seems unaffected by behavioral factors. Furthermore, sleep-related erections are present across the life span with only a slight decline in older healthy people. Analogous phenomena are present in women. The function of sleep-related erections is not known; however, they clearly involve vascular, neurologic, and hormonal mechanisms. Sleep-related erection testing provides a physiologic, objective, diagnostically useful technique for evaluating erectile capacity. Laboratory-based studies with comprehensive polysomnography offer the most complete diagnostic picture of erectile function available. Nonlaboratory procedures require further validation. The sleep-related tumescence pattern contains a wealth of information about the physiology and pathophysiology of erection. The coordination between REM sleep and erection, the differential expansion at the penile base and upper shaft, and the rate of circumference increase and decrease are meaningful indicators for determining if erectile dysfunction exists. Sleep-related erection testing indexes the magnitude and nature of organic involvement and takes the differential diagnosis of impotence beyond a simplistic psychogenic-organic dichotomy.

Adult↗
PubMed1995

Inhibition of steroid 5 alpha-reductase with finasteride: sleep-related erections, potency, and libido in healthy men.

To objectively measure the effects of a 5 alpha-reductase inhibitor on erectile function, we studied 20 sexually active men (aged 41-64 yr) during double blind, randomized administration of 5 mg/day finasteride (F) or placebo (P). Serum testosterone and dihydrotestosterone (DHT) were measured every 4 weeks. Sleep-related erections were assessed with comprehensive polysomnography for 2 nights before randomization (session 1) and at week 12 (session 2). Sexual function questionnaires were administered weekly. Serum DHT levels at week 0 were 1.47 +/- 0.11 and 1.16 +/- 0.27 nmol/L (P > 0.05) in the P and F groups, respectively. F group levels fell to 31% and 28% of control values at week 4 and 12. Penile tip peak tumescence time increased on second nights more in the P than the F group at 12 weeks, producing a session main effect (P < 0.02) and a group X session interaction (P < 0.05). No significant group X session interactions were found for any sleep erection measures in a best night analysis or for self-reported sexual activity. Thus, F did not consistently suppress sleep-related erections compared to P. F primarily inhibits type 2 5 alpha-reductase activity; however, type 1 5 alpha-reductase is the major enzyme in the central nervous system. Therefore, DHT involvement in the maintenance of libido and potency is not excluded. Nonetheless, these data support the feasibility of using a type 2 inhibitor to treat benign prostatic hyperplasia without impairing erectile function.

5-alpha Reductase Inhibitors↗
PubMed1995

CPAP machine performance and altitude.

UNLABELLED: STUDY RATIONALE AND OBJECTIVE: Sleep-disordered breathing is commonly treated with nasally applied continuous positive airway pressure (CPAP). Typically, pressures are titrated to pneumatically splint the airway to prevent its collapse in response to negative inspiratory pressure. This investigation was prompted by several patient complaints of sleep-related breathing difficulty associated with travel to high altitudes. CPAP devices create pressure with fan-generated airflow; therefore, CPAP performance should behave according to collective fan laws. MEASUREMENTS AND RESULTS: In the present study, we examined the effect of simulated altitude change on four commercially available CPAP machines. Machines were tested using anatomic airway mannequins in an altitude chamber. We made three simulated ascents to 12,000 feet with machines set at 5, 10, and 12 cm H2O sea level pressure equivalents. We measured pressure using water manometers at 2,000-foot increments during ascent and descent. Mask pressures varied systematically with changing altitude in three machines. One machine, equipped with a pressure regulation feature, maintained pressure within 1 mm H2O at all pressure and altitude combinations. CONCLUSIONS: Altitude significantly alters delivered pressure according to predictions made by the fan laws, unless a unit has pressure-compensating features. Clinicians should consider this factor when CPAP is prescribed for patients who live or travel to places located at significantly higher or lower elevations than the titration site.

Altitude↗
PubMed1994

Issues in computerized polysomnography.

Reliable, properly tested, computerized systems for recording and scoring polysomnographic data would be welcome assistants in sleep laboratories. They potentially could save time, effort, paper, storage and cost. There exists, however, questions of competence and confidence. The nature and scope of published literature fails to convince many cautious sleep specialists that the cost-benefit ratio is favorable. Nonetheless, computerized systems for polysomnography are here to stay and are improving. Most of us represent past, present or future consumers of these products. The market will adjust to our level of knowledge and demands. We can adopt a variety of perspectives; however, the three basic modes of use should guide our thinking. For clarity, it is helpful to dissect 1) recording issues, 2) scoring issues and 3) monitoring issues from one another. Also, we should insist on greater statistical sophistication in testing trials. Manufacturers face a dilemma. Sleep disorders medicine has few true standards and many idiosyncratic practices. The expertise of consultants vary and manufacturers may be in no position to judge their collaborators. We desperately need guidelines to meet both manufacturers' and clinicians' expectations for testing and using computerized polysomnography.

Humans↗
PubMed1992

Nocturnal penile tumescence in cigarette smokers with erectile dysfunction.

We examined the relationship between cigarette smoking and erectile physiology in 314 men with erectile dysfunction. All of the men studied were currently cigarette smokers. Evaluations included interviews, physical examinations, and polysomnographic assessment of sleep-related erections. Penile rigidity during nocturnal erection inversely correlated with the number of cigarettes smoked per day. Smoking was also associated with indices of impairment on autonomic function tests and some measures of penile blood pressure. The group of men who smoked the most (more than 40 cigarettes per day) had the fewest minutes of nocturnal tumescence and detumesced fastest. These data are discussed with respect to the results of studies performed in dogs that demonstrated smoking-related reduction in arterial flow and venous restriction. Our findings suggest that smoking may further compromise penile physiology in men experiencing difficulty in maintaining erections long enough for satisfactory intercourse.

Adult↗
PubMed1992

Characteristics of penile erections during sleep recorded from normal subjects.

The results of penile tumescence recordings from first- and second-night polysomnograms from 146 normal subjects are presented for four age groups. The data are in close agreement with basic tumescence parameters that have been presented earlier. In addition, results from first and second nights are compared, and data are presented from base and coronal sulcus (tip) recordings locations. The results indicate that tumescence parameters that are most correlated with rapid-eye-movement sleep are those most likely to significantly differ from the first to the second night. Base and tip recordings closely paralleled each other. Additionally, tumescence periods were also divided into three phases that are likely to correspond to different physiological states. These three phases, Tup, Tmax, and Tdown, vary in their sensitivity to night and age effects. It is hypothesized that changes in different tumescence phases may reflect different pathophysiologies.

Adult↗
PubMed1992

Polysomnography of adults and elderly: sleep architecture, respiration, and leg movement.

Polysomnographic data recorded from a large sample of normal, healthy, adult volunteer subjects are reported. First and second night summary values are included. Results agree remarkably well with previously published findings and the age-related differences in sleep architecture that we found are described in detail. We also discuss some of the unique methodological problems associated with developing normative sleep values.

Adult↗
PubMed1990

Prevalence of sleep apnea in men with erectile dysfunction.

Sleep studies were performed on 1,025 patients complaining of erectile dysfunction. In addition to standard measures of sleep stage and nocturnal penile tumescence, respiratory activity was evaluated. The number of episodes of sleep apnea per hour (Apnea Index--AI) was calculated for each patient. The overall prevalence of sleep apnea activity in this sample was: 43.8 percent with AI greater than or equal to 5; 27.9 percent with AI greater than or equal to 10; and 19.6 percent with AI greater than or equal to 15. These results confirm that sleep apnea activity is common in men with erectile dysfunction. This high prevalence also indicates that further study is needed to elucidate pathophysiology of erectile failure in men with sleep apnea.

Adult↗
PubMed1990

Diabetes, erectile dysfunction, and sleep-related erections.

Sleep-related erections were assessed in conjunction with polysomnography in 100 diabetic and 400 nondiabetic men with complaints of erectile problems. We also measured bulbocavernosus reflex latency, heart rate response to deep breathing, postural-related blood pressure changes, penile arterial sufficiency, and brachial blood pressures. To investigate the relationship between diabetes and erectile capacity, the results obtained from men with and without diabetes were compared. Men with diabetes had fewer sleep-related erections, less tumescence time, diminished penile circumference increase, and lower penile rigidity than nondiabetic men. These diabetes-related differences were found regardless of the maximum penile rigidity observed. The diabetic group had less heart rate response to deep breathing and lower penile blood pressures than the nondiabetic group, but only among men with maximum penile rigidity less than 500 g. These data indicate that both neurological and vascular mechanisms are involved to a greater degree in organic diabetic impotence than in the organic erectile dysfunction that occurs in nondiabetic men. Finally, the pattern of lower values for measures of nocturnal tumescence among diabetic men, compared to nondiabetic men, occurred in all age groups, except the oldest. Among impotent men, age 65 years or older, no difference was found between men with and without diabetes. This suggests that diabetes may foreshadow some of the age-related pathophysiological processes associated with erectile dysfunction.

Adult↗
PubMed1990

Testosterone replacement therapy and sleep-related erections in hypogonadal men.

Hypogonadal men usually have diminished libido and erectile dysfunction, and testosterone replacement therapy in these men increases sexual activity, erotic thoughts, and self-reported nocturnal erections. The polygraphic assessment of nocturnal penile tumescence (NPT) provides an objective index of erectile capability and is useful for differentiating psychogenic from organic erectile dysfunction. In this study we evaluated NPT in six hypogonadal adult men during and after termination of androgen therapy. Multinight sleep studies were conducted within 1 week and 7-8 weeks after each man received 20 mg testosterone cypionate, im. The mean serum testosterone level 4-7 days after testosterone injection was 35.9 +/- 3.4 (+/- SE) nmol/L, and it fell to 2.3 +/- 0.9 nmol/L after 7-8 weeks. Significant declines (P less than 0.05) in the number of NPT episodes (3.7 to 2.0), maximum penile circumference increase (24 to 13 mm), and total tumescence time (107 to 55 min) accompanied the fall in the serum testosterone level. No androgen-related changes in the amount or integrity of rapid eye movement sleep were found. Finally, the mean penile rigidity (buckling pressure) decreased from 770 +/- 98 to 590 +/- 81 g (P less than 0.05). Comparison of these results to those in normal men revealed that none of these men met all diagnostic criteria for organic impotence, even 7-8 weeks after discontinuation of testosterone administration. While men with androgen deficiency may have normal NPT, sleep-related erections increase in response to testosterone administration.

Adult↗
PubMed1989

Erectile dysfunction in hypertensive men: sleep-related erections, penile blood flow and musculovascular events.

To explore how hypertension affects penile erection, we studied erectile hemodynamics during nocturnal penile tumescence in 3 groups of middle-aged men: hypertensive patients with and without erectile dysfunction, and normotensive controls without erectile problems. The hypertensive patients were not taking antihypertensive medication. Evaluations included standard monitoring of penile circumference change as well as noninvasive monitoring of penile segmental pulsatile blood flow and activity in the bulbocavernosus-ischiocavernosus muscles. Variables differed in how they discriminated among groups. Median amplitude of penile blood flow during rapid eye movement sleep differed significantly among all 3 study groups: controls had the highest amplitudes, patients without erectile problems had lower values and patients with erectile complaints had the lowest values. By contrast, standard measures of nocturnal penile tumescence (that is based on penile circumference change during sleep) only distinguished the patients with erectile problems from the 2 other groups. Density of musculovascular event clusters during rapid eye movement sleep (nearly simultaneous muscle activity burst, blood flow burst and circumference pulsation) distinguished the 2 groups of hypertensive men from controls. The sensitivity of the blood flow measure to changes in the hypertensive men without erectile complaints may indicate that the measure can reveal subclinical signs of developing vasculogenic erectile dysfunction.

Hemodynamics↗
PubMed1989

Hypertension, erectile dysfunction, and occult sleep apnea.

Sleep-related respiratory pattern was evaluated in 175 hypertensive and 110 normotensive men, none of whom reported difficulties in initiating or maintaining sleep. Patients were grouped according to sexual status (complaint of erectile problems), hypertension treatment status (treated or untreated), and blood pressure (diastolic less than 90 or greater than or equal to 90). The prevalence of sleep apnea, apnea index, duration of the longest episode of apnea, and penile rigidity were tabulated. The group with elevated blood pressure, persistent even with antihypertensive drug therapy, had the most sleep apnea. The treated hypertensive men with controlled blood pressure had significantly less apnea than those whose blood pressure remained high. Untreated hypertensive groups, however, did not differ from normotensive groups with respect to apnea. Evidence of abnormal sleep-related respiratory activity was found in both hypertensive and normotensive groups with erectile problems. Interestingly, penile rigidity was significantly lower for hypertensive men with erectile complaints than for normotensive men with erectile complaints. There was also a small, but significant, negative correlation between apnea index and penile rigidity among men with erectile complaints. These results indicate that sexual status is an important consideration in the diagnosis of hypertension and sleep apnea. Moreover, these data suggest an interrelationship among hypertension, erectile dysfunction, and sleep apnea.

Antihypertensive Agents↗
PubMed1987

Penile blood flow and musculovascular events during sleep-related erections of middle-aged men.

The relationships among penile segmental pulsatile blood flow, pelvic musculovascular events, phases of nocturnal penile tumescence, and sleep stages were studied by all-night polysomnography in 23 healthy middle-aged men. Penile blood flow peaked during maximal tumescence. Bursts of phasic musculovascular activity were more frequent during ascending and maximal tumescence than during detumescence and baseline. Both penile blood flow and the number of musculovascular events increased during REM sleep. These data describe important local aspects of penile erectile mechanisms in normal men. The findings on musculovascular events support the notion that the bulbocavernosus-ischiocavernosus muscles have a role in human penile erection.

Adult↗
PubMed1986

Cerebral responses evoked by stimulation of vesico-urethral junction in man: methodological evaluation of monopolar stimulation.

Cerebral responses after bipolar stimulation (BpS) and monopolar stimulation (MpS) of the vesico-urethral junction (VUJ), as well as skin surface stimulation of various hip and pelvic structures, were recorded in 13 normal control subjects. BpS of VUJ produced cerebral evoked potentials (CEPs) with a negative peak (mean latency 88.69 +/- 13.73 msec) following a smaller positive deflection, while MpS of the same sites with indifferent electrodes placed on various pelvic or hip structures resulted in different response latencies that were all significantly shorter than those of BpS. Shape and latency of responses after MpS of VUJ were similar to those elicited by skin surface stimulation of the abdominal wall and the iliac crest; those elicited by pudendal nerve stimulation at the glans were also similar in shape but significantly greater in latency. Results strongly indicate that during MpS of VUJ the somatic or muscle afferents located in the hip and pelvic region are stimulated; consequently, BpS technique should be considered the preferred technique for investigating the physiological condition of visceral afferents arising from VUJ.

Adult↗
PubMed1986

Uterine activity during sleep.

REM-related increases in uterine activity were found in 10 healthy young adult volunteer subjects. Contraction baseline pressures were elevated compared with NREM sleep, stage 2 sleep, stages 3 and 4 slow wave sleep (SWS), and stage 0. Contraction amplitudes during REM sleep were greater than those during SWS and stage 0, while contraction rates differed only between REM sleep and SWS. The results strongly indicated a cycle of genital activity in women that parallels the penile erection cycle in men. The implications of this finding and suggestions for future research are discussed.

Adult↗