Premature Ejaculation Causes

Premature ejaculation (PE) is probably the most common sexual dysfunction presented by men or couples. It's also been called rapid or early ejaculation; it can affect men of all ages, both from the beginning of their sexual career, or it may develop unexpectedly later in life.

Anatomy and Physiology

Before we discuss the causes of premature ejaculation, we need to briefly review the anatomy and physiology of the male reproductive system. Ejaculatory fluid is formed by an amalgam of secretions from the seminal vesicles, the prostate, and the glands that open into the urethra. The bladder neck is located proximal to the paired ejaculatory ducts, and during ejaculation it acts as a sphincter to prevent flow of semen into the bladder. During ejaculation, the smooth muscle around the urethra is subject to the control of the autonomic nervous system, and contracts to activate the sphincter.

On the distal side of the ejaculatory ducts there is an external urethral sphincter, which consists of two layers of muscle: the central layer is under the control of the autonomic nervous system, and the outer layer is under somatic control. This muscle contracts before the emission of semen into the base of the urethra so that in effect there is an enclosed pressure chamber created in the prostatic area of the urethra. The ejaculation process involves relaxation of the sphincter so that the semen can flow down the urethra and out of the penis.

In neurological terms, ejaculation is a process which is controlled by both the central and peripheral nervous system. To start with, the cutaneous nerves of the penis are fundamental to the mechanism of the ejaculatory process. When stimulated, these nerves send impulses through the pudendal nerve to the spinal-cord: the specific area in the brain which acts as the control centre of ejaculation has not been fully determined, although the hypothalamus seems to play a major role in the process.

The nerves which are responsible for ejaculation travel down from the cerebral  cortex to the thoracolumbar and sympathetic nervous system chains at the area of T10 to T3. Postsynaptic adrenergic fibers then take a route through the superior hypo-gastric plexus located at the aortic bifurcation, before they disburse laterally near the area of the bladder and rectum to the end organs (which include the epididymis, the seminal vesicles, the vas deferens, prostate gland and the neck of the bladder. The actual expulsion of semen from the pressure chamber in the posterior urethra is stimulated by activation of the nervous system fibers within the pudendal nerves originating from S2 to S4.

The Physiology Of Ejaculation

As we've seen, ejaculation is basically a co-ordinated activity of different systems of the body so that the seminal fluid, once deposited into the posterior urethra, is then subsequently expelled through the urethra and urethral meatus. There are actually three phases of the ejaculatory process: the first is bladder neck contraction, the second is emission (the moment when semen is released into the base of the urethra), and the third is ejaculation. Naturally enough, these three events occur in a very ordered and systematic physiological sequence. To start with, during emission, smooth muscles located inside the prostate gland, seminal vesicles, and vas deferens contract in a rhythmic fashion that causes the semen to be deposited into the posterior urethra. At the same time, the neck of the bladder, which contains smooth muscle fibers, is contracting so as to prevent the retrograde flow of semen into the bladder. After the semen has been successfully deposited into the posterior urethra, the external urethral sphincter relaxes and the urethral skeletal muscles contract in a rhythmic fashion to ejaculate semen in pulses through the urethra.

This latter sequence of the ejaculatory process is the result of stimulation from branches of the pudendal nerves originating from S2-S4. These are muscles which are normally under voluntary control; however, during the process of ejaculation all of the events are in voluntary once the reflex has been initiated.

Ejaculation is normally caused by a combination of sexual activity which results in sensory stimulation from the genitals coordinated with erotic imagery and thoughts in the cerebral cortex. This input from the cortex actually enhances the sensory stimulation of the penis, but nonetheless, the ejaculation reflex is something which can be activated by cerebral input alone -- as demonstrated by the phenomenon of nocturnal emission.

But What Causes Premature Ejaculation?

It's remarkable that despite the fact that premature ejaculation is a problem for so many men (estimates ranging from 50 to 75% of the male population), its etiology is not understood fully. In the era when psychodynamic explanations held sway, premature ejaculation was thought to be the result of an unconscious conflict (such as between sexual desire and hostility towards one sexual partner). However, in the later era where behavioral theory tended to hold precedence, premature ejaculation was regarded as a learned behavior and/or the product of performance anxiety.

In recent times a neurobiological explanation has been favored, and rapid ejaculation has tended to be regarded as a condition that results from anomalies within the nervous system such as oversensitive penile nerves or an imbalance of dopamine and serotonin in the brain (within the central nervous system, dopamine seems to act as an excitatory agent, while serotonin appears to be excitatory). There has even been a suggestion that rapid ejaculation is caused by a delay in processing sensory nerve stimulation in the central nervous system.

One has to keep in mind that since almost all men are rapid ejaculators at the start of their sexual career, and only a small percentage manage to achieve greater control of their ejaculation, particularly to the point where it becomes a voluntary decision to ejaculate, it may well be that we are biologically programmed to ejaculate quickly:
it actually makes good sense for a mammal in a hostile environment to mount, penetrate, and ejaculate inside its partner as quickly as possible. It could well be that in seeking an explanation and cure for premature ejaculation, categorizing it as a disease or a problem, or at the very least as a sexual dysfunction, we have the wrong orientation in our enquiry. It may be more appropriate to ask how it is that men learn to last for as long as they desire when they make love, and then to explore and analyze the methods that they have used, either consciously or unconsciously, to become longer lasting lovers.

Despite this, of course, scientists continue to search for an explanation and treatment. One of the basic criteria for describing sexual dysfunction is to classify it, and premature ejaculation is no exception: it has been divided into two types - primary and secondary, where primary premature ejaculation refers to the presence of rapid ejaculation since puberty; men who have secondary premature ejaculation will experience the onset of rapid ejaculation later in life. If premature ejaculation is acquired, i.e. it develops later in life after previously successful attempts to control ejaculation, it is vital that the doctor or therapist addresses the issue of when the PE started, or what events were happening when it began.

Other factors to establish is whether the PE is situational and whether it occurs with only certain partners. It is also relevant to establish the length of time between the beginning of sexual sensory stimulation and ejaculation during masturbation, oral sex, and intercourse: in assessing a man's sexual function, the degree of voluntary control that he believes he has over his ejaculation is also important. Lastly, for those who are seeking to treat the disease in a face-to-face interaction, it's important to establish how much the man and his partner experience distress because of his rapid ejaculation. (Some couples are not disturbed by the phenomenon because they have incorporated it into their lovemaking in a way that allows both of them to reach satisfaction. A common model for this would be the man bringing the woman to orgasm before he penetrates her; many couples report that under these conditions the woman is much less bothered by his failure to maintain long lasting thrusting.)

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