Sleep, 1(2): 125-132 © 1978 Raven Press, New York Impotence and Blood Pressure in the Flaccid Penis:. Relationship to Nocturnal Penile Tumescence Downloaded from https://academic.oup.com/sleep/article/1/2/125/2749493 by guest on 27 September 2021 Ismet Karacan, J. Catesby Ware, Baris Dervent, Attila Altinel, John I. Thornby, Robert L. Williams, Nusret Kaya, and F. Brantley Scott Sleep Disorders Center, Department of Psychiatry, Baylor College of Medicine, and Sleep Laboratory, Veterans Administration Hospital, Houston, Texas Summary: Evaluations of nocturnal penile tumescence (NPT) and penile blood pressure were performed on (1) a group of nondiabetics with normal NPT, (2) a group of nondiabetics with abnormally diminished NPT, and (3) a group of diabetics with abnormally diminished NPT. The 12 subjects in each group complained of impotence. Analysis of blood pressure data taken before the NPT evaluation suggests the possibility of selective low arterial blood pressure in impotent patients who show no obvious signs of other vascular disorders. Key Words: Nocturnal penile tumescence-Penile blood pressure-Sleep­ Impotence-Diabetes. The recording of nocturnal penile tumescence (NPT) and other polysomno­ graphic parameters has led to the development of an evaluation technique that establishes the presence of organic factors contributing to erectile impotence (Karacan, 1970; Fisher et aI., 1975; Karacan et aI., 1977; Karacan et aI., 1978). Overall, it is still believed that approximately 90% of all cases of impotence have psychogenic etiologies (Sherman, 1975); however, our evaluations of more than 400 patients complaining of impotence suggest that a higher percentage of patients have contributing organic factors than is generally recognized. Systematic research has shown that normal males of all ages who have no sleep disturbance and no complaints of erectile dysfunction, and who take no alcohol or drugs, have regularly occurring periods of NPT in association with REM sleep (Fisher et aI., 1965; Karacan, 1965; Kahn and Fisher, 1969; Hursch et aI., 1972; Karacan et aI., 1972a ,b ,c, 1975, 1976). However, polysomnographic evaluations of men complaining of impotence (the inability to initiate or maintain penile erection) Accepted for publication June 1978. Address reprint requests to Dr. Karacan, Sleep Disorders Center, Baylor College of Medicine, Houston, Texas 77030. 125 126 1. KARACAN ET AL. reveal a subgroup with abnormal patterns of NPT (Karacan, 1970; Fisher et aI., 1975; Karacan et a!., 1975). We have found that these abnormal patterns generally consist of diminished expansion of circumference both at the tip and at the base of the penis during erection. Other abnormal patterns seen are diminished tip expan­ sion only, diminished base expansion only, and increased nonREM (NREM) tumescence with reduced REM tumescence time. To some extent, the type of NPT abnormality is indicative of specific factors contributing to impotence. Those patients who complain of erectile impotence, but who have normal NPT, Downloaded from https://academic.oup.com/sleep/article/1/2/125/2749493 by guest on 27 September 2021 will often have psychological characteristics that are different and more sugges­ tive of psychogenic impotence than those with abnormally diminished tumescence (Beutler et aI., 1975); however, the presence of psychological factors does not preclude concomitant organic factors. Conversely, we have seen several patients who complained of impotence following an accident, but who had normal NPT. Later these patients have shown Clinical recovery. Despite the ability to recognize the presence of general pathology, little is known of specific causes of erectile impotence. Of particular interest has been the relationship between penile blood pressure and impotence. The literature does not include arterial obstruction as a prominent cause of impotence, although there is evidence indicating that arterial obstruction is a factor in impotence. Gaskell (1971) measured penile blood pressure of normal subjects and of potent and impo­ tent patients with signs of occlusive diseases. In most of the impotent patients, even those with no symptoms of peripheral vascular disease, penile blood pres­ sure was well below brachial pressure. Malvar et a!. (1973) used a Doppler flowmeter to examine flaccid penile flow in 36 potent and impotent patients and found that flow was lower in the impotent patients. Finally, Abelson (1975) used an ultrasonic Doppler method to study normal subjects and impotent diabetics. He reported that in normal subjects penile systolic pressures were intermediate be­ tween arm and leg systolic pressures, and penile diastolic and mean pressures were significantly higher than were values for the arm or leg. Six of the 14 impotent patients exhibited an abnormally low penile blood pressure. To date, none of the studies reporting on penile blood pressure has differen­ tiated impotence in terms of NPT measurements. In order to evaluate the relation­ ship between complaints of impotence, the degree of erectile capability, and penile blood pressure, we examined three groups of patients: 1. Those with a complaint of impotence, but who had normal NPT (patient control group). 2. Those with a complaint of impotence who had abnormaIIy diminished NPT, but who were free of other physical problems (nondiabetic group). 3. Those with a complaint of impotence who had abnormaIIy diminished NPT, and who had diabetes (diabetic group). Our expectations were that the diabetic group would have the lowest penile blood pressure of any group, followed by the nondiabetic group, and finaIIyby the patient control (normal NPT) group. Since vascular damage to large and smaII vessels is characteristic of diabetics (Norris and Yunis, 1964; Warren et a!., 1966), it is logical to conclude that in some impotent diabetics damage to vessels that feed the penis may compromise adequate blood flow to the penis and therefore prevent Sleep, Vol. I, No.2, 1978 NPT AND PENILE BLOOD PRESSURE 127 normal erection. Either simple occlusion of the vessels or more complex changes affecting the dynamic pattern of vascular events that take place during erection could produce erectile failure. Fournier and Huguet (1968) reported that arterio­ grams of the penis of impotent diabetics revealed areas of complete avasculariza­ tion in the cavernosus tissue. By contrast, nondiabetic patients who suffered from arteriosclerosis had good vascularization of the corpora cavernosa, in spite of large and diffuse arterial lesions. Downloaded from https://academic.oup.com/sleep/article/1/2/125/2749493 by guest on 27 September 2021 METHOD Subjects Subjects were selected from the patients who had been referred to us for evalua­ tion of NPT. All patients were initially given a detailed explanation of the proce­ dure to be used and signed a written informed consent form. The last 260 patients we evaluated had also received a peripheral vascular evaluation. From this group, 36 subjects were selected for three different groups. Patients were not included if they were taking any medication other than insulin. Also, patients with medical disorders other than diabetes and impotence (e.g., hypertension, Peyronie's dis­ ease, spinal cord injury, or known cardiovascular problems) were excluded. Procedure After a detailed interview, Minnesota MUltiphasic Personality Inventory (MMPI) , and general physical and neurological examinations, each patient was given an extensive blood pressure examination. Arterial blood pressures were measured by means of a Roche Doppler system, and recorded on a strip chart. Blood pressure was recorded from the following locations: left and right brachial (supine, sitting, standing); left and right finger (supine); left and right popliteal (supine); left and right toe (supine); and left, right, and midline dorsal flaccid penis (supine and standing). During all blood pressure measures, pulse volume was also reco~ded by means of a photoreflectance plethysmograph placed distally to the blood pressure cuff. The patients then went through a three-night polysomno­ graphic evaluation. The standard electroencephalographic-electrooculographic parameters were recorded (Williams et al., 1974) along with two penile circumfer­ ence channels. Penile circumference was monitored by means of mercury-filled strain gauges (Karacan, 1969) placed around the penis. One gauge was placed at the tip of the penis, just caudal to the glans, and the other was placed at the base. On one evaluation night the patient was awakened during a typical erection to measure the rigidity of the erection. After the three-night evaluation, the patient's NPT was categorized as normal, low-borderline normal, abnormally diminished, or absent in comparison to values for age-matched control subjects, by taking into account the number of NPT episodes, the change in circumference, the duration of each episode, and the rigidity of the erection (Karacan, 1977). This categoriza­ tion was made in case conferences following completion of the evaluation procedures. For this study, the subjects were then placed in one of three groups. Subject Sleep, Vol. I. No.2, 1978 128 I. KARACAN ET AL. grouping was "blind" with respect to knowledge of blood-pressure values. Except for knowing the categorization of NPT (normal, low-borderline normal, abnor­ mally diminished, absent), the grouping was done blind to exact NPT measures. Group I: Patient control group. These patients complained of impotence. The result of the NPT evaluation indicated