Causes and treatment of hypersexuality, penile erection mechanism, and etiology of erectile dysfunction (ED)

Hypersexuality refers to an excessively strong libido that exceeds normal sexual desire, resulting in frequent sexual arousal, an urgent need for sexual activity, increased frequency of intercourse, and prolonged intercourse. Even mild sexual stimulation can trigger sexual desire, leading to constant and persistent sexual urges, regardless of time, place, occasion, or intimacy with the partner. The individual repeatedly demands sexual intercourse to satisfy their desires and is unable to control themselves. Hypersexuality affects approximately 1% of the general population, characterized by a constant state of sexual urges and a craving for sex in all aspects of life; in severe cases, it can lead to obsessive sexual activity. The individual seeks every possible sexual partner and opportunity for sexual intercourse, relentlessly demanding sexual intercourse. When this desire is intense and cannot be expressed, the patient may experience anxiety, irritability, masturbation, agitation, palpitations, dizziness, insomnia, weakness in the limbs, and blank stares. It is often accompanied by disordered sexual relationships, even prostitution, soliciting, and rape. The patient's reactions are also abnormally intense; even hugging and kissing can produce intense orgasms, and the unbearable pain can lead to suicide. For young adults, normal sexual activity occurs 1-3 times per week. Newlyweds or couples reuniting after a long separation may experience a slight increase in frequency and arousal, which is perfectly normal. Generally, if both partners are satisfied with their sexual arousal and behavior, any increase without adverse consequences should not be considered pathological. However, due to individual differences and the difficulty in distinguishing between normal and excessive libido, there is currently no definitive standard for judgment.

The main cause of hypersexuality is enhanced excitation of the sexual center, which can be divided into two categories: physical and psychogenic. Physical causes include temporal lobe lesions, encephalitis, and excessive use of testosterone, cannabis, cocaine, etc. Brain lesions, especially those affecting the sexual centers of the brain or hypothalamus, such as pituitary and gonadal lesions, can lead to excessive gonadotropin-releasing hormone, causing increased secretion of gonadotropins and sex hormones, resulting in hypersexuality. 10%–20% of patients with hyperthyroidism experience hypersexuality in the early stages, especially those with mild hyperthyroidism. Hyperadrenocortical hyperfunction can increase male sex hormone secretion, also leading to hypersexuality. Psychogenic causes can be seen in certain obsessive-compulsive disorders, mania, schizophrenia, and paranoid psychosis, as well as in individuals without mental illness but with subconscious psychological abnormalities.

First, the cause of the hypersexuality must be identified. If no organic lesion is found, the couple can separate for a period of time to reduce sexual stimulation. Simultaneously, psychological therapy and sex education should be provided, along with participation in recreational and sports activities, and focusing energy on work and study. In addition, appropriate medication can be used, such as sedatives to relieve the patient's sexual urges, such as diazepam, meprobamate, or chlorpromazine. Hormone therapy can also be used to antagonize its effects; for example, estrogen can be used for male hypersexuality, and for hypersexuality caused by organic lesions, treatment can target the organic lesion. It should be noted that administering large doses of estrogen to male patients can easily cause gynecomastia; in recent years, cyproterone acetate has been commonly used.

Penile erection refers to the firming of the penis from a flaccid state. It is generally divided into two categories: psychogenic erection and reflexive erection. Psychogenic erection (or cerebral erection) is caused by excitation of the cerebral cortex and is more common in young men. Reflexive erection occurs when the sexual organs are stimulated, and impulses are transmitted from the pudendal nerve to the erection center in the sacral spinal cord, causing penile engorgement and hardening. These two types of erections can occur sequentially or reinforce each other.

The erection mechanism is mainly caused by certain sexual stimuli to the higher nerve centers of the brain, such as visual, auditory, olfactory, tactile, cognitive, or sexual hallucinations. These stimuli excite the erection center in the sacral segment of the spinal cord, and then transmit the signals along the sympathetic nervous system to the reproductive organs. This causes the penile arterioles to dilate, increasing blood flow, resulting in local congestion and increased internal pressure. At the same time, venous return is obstructed, leading to penile thickening and maintaining an erection. Simply put, the process of erection is the result of sexual stimulation, which, under the influence of the nervous system, greatly increases the blood flow into the penis while reducing or even temporarily stopping the blood flow out of the penis.

A normal man, including children, can experience nocturnal penile erections at any age. After puberty, the frequency and duration of nocturnal erections increase, averaging 5-6 times per night, each lasting 20-30 minutes. Even after the age of 60, there is still a cumulative 1-1.5 hours of erections per night.

The penis may become erect in the following situations: upon waking in the morning or when the bladder is compressed by excess urine; during exercise when the penis rubs against the pants; when having sexual thoughts, reading sexually related books or magazines, having sexual fantasies, or watching scenes in movies; most of the time, erections are triggered by sexual arousal, such as when you or someone else sexually touches or squeezes the penis or scrotum; the penis can also become erect spontaneously without any apparent reason, which is very common in adolescent boys.

Erectile dysfunction (ED), also known as impotence, refers to the persistent inability of the penis to achieve or maintain an erection sufficient for satisfactory sexual intercourse, lasting for more than 3 months. In other words, the penis cannot achieve an erection, or the erection is of poor rigidity, making penetration difficult or impossible, or the erection becomes flaccid after a very short time, preventing the completion of sexual intercourse.

The causes of erectile dysfunction can be divided into:

(1) Psychogenic ED: refers to erectile dysfunction caused by mental and psychological factors such as tension, depression, anxiety and marital discord.

(2) Organic ED: This can be further divided into the following five categories. ① Vascular causes. These include any disease that may reduce blood flow to the penile cavernous arteries, such as atherosclerosis, arterial injury, arterial stenosis, pudendal artery shunt, and abnormal cardiac function, or penile venous leakage caused by a reduction in the smooth muscle of the tunica albuginea or cavernous sinus that impairs the venous return closure mechanism. Arterial congestion and venous closure are essential for maintaining penile erection. If arterial congestion is reduced or venous return is accelerated, it will result in poor penile erection or no erection. ② Neurological causes. Diseases or injuries to the central and peripheral nerves can lead to erectile dysfunction. ③ Surgery and trauma. Major vascular surgery, radical prostatectomy, abdominoperineal resection for rectal cancer, and other surgeries, as well as pelvic fractures, lumbar compression fractures, or straddle injuries, can cause damage to the blood vessels and nerves related to penile erection, leading to erectile dysfunction. ④ Endocrine disorders, chronic diseases, and long-term use of certain medications can also cause erectile dysfunction. Especially male hormones; low levels of these hormones significantly impact penile erection. Sexual behavior in male mammals is hormone-dependent. In animal experiments, castrated male mammals exhibit significantly reduced, even absent, sexual behavior. Ejaculation is the first function to disappear, followed by erectile and intercourse abilities. Supplementation with testosterone can reverse this, first restoring mating ability, and finally ejaculation. For humans, androgens are essential for maintaining male sexual function. ⑤ Diseases of the penis itself, such as Peyronie's disease, penile curvature, severe phimosis, and balanitis.

(3) Mixed ED: refers to erectile dysfunction caused by a combination of psychological factors and organic causes. In addition, because organic ED is not treated in time, patients experience increased psychological pressure and fear of sexual failure, making ED treatment more complicated.