All studies demonstrate a strong association with age, even when data are adjusted for the confounding effects of other risk factors. The independent association with aging suggests that vascular changes in the arteries and sinusoids of the corpora cavernosa, similar to those found elsewhere in the body, are contributing factors. Other risk factors associated with aging include depression, sleep apnea, and low HDL levels.
The development of an erection is a complex event involving integration of psychologic, neurologic, endocrine, vascular, and local anatomic systems. Positron emission tomography scanning studies have suggested that sexual arousal is activated in higher cortical centers that then stimulate the medial preoptic and paraventricular nuclei of the hypothalamus.5 These signals ultimately descend through a complex neural network involving the parasympathetic nervous system and eventually activate parasympathetic nerves in the sacral area (S2 to S4).
Before pursuing ED treatments, though, bear in mind that improving heart health by losing weight, eating a healthier diet, exercising more and quitting smoking typically enhances erectile performance as well as one’s overall health. In addition, sex therapy counseling sessions can often ease or eradicate ED symptoms, if the underlying cause is psychological in nature, says Drogo Montague, M.D., director of the Center for Genitourinary Reconstruction at the Cleveland Clinic. 

Oral PDE5i remains the first line treatment for NED from SCI. Three of the four PDE5i currently available in the U.S., avanafil excluded, have been investigated in the SCI, and all of the more recent studies have shown improvements in erectile function based on IIEF score compared to placebo when included (59-63). Other studies have also shown significant improvements in the IIEF score when compared to baseline (64-69). Furthermore, treatment efficacy when compared to placebo occurs despite LOI or American Spinal Injury Association (ASIA) score characterizing impairment related to the injury (59,61).
Think of erectile dysfunction as your body’s “check engine light.” The blood vessels in the penis are smaller than other parts of the body, so underlying conditions like blocked arteries, heart disease, or high blood pressure usually show up as ED before something more serious like a heart attack or stroke. ED is your body’s way of saying, “Something is wrong.” And the list of things that cause erectile dysfunction can include:
Penile prostheses are very effective, and most patients who have a prosthesis placed are satisfied with the prosthesis. However, placement of a prosthesis causes scarring of the tissue within the corpora cavernosa, and if the prosthesis requires removal, other forms of therapy, except for the vacuum device, are often not effective. Thus, most physicians reserve placement of a prosthesis for men who have tried and failed or have contraindications to other therapies.

Additionally, the physiologic processes involving erections begin at the genetic level. Certain genes become activated at critical times to produce proteins vital to sustaining this pathway. Some researchers have focused on identifying particular genes that place men at risk for ED. At present, these studies are limited to animal models, and little success has been reported to date. [4] Nevertheless, this research has given rise to many new treatment targets and a better understanding of the entire process.


Erections occur in response to tactile, olfactory, and visual stimuli. The ability to achieve and maintain a full erection depends not only on the penile portion of the process but also on the status of the peripheral nerves, the integrity of the vascular supply, and biochemical events within the corpora. The autonomic nervous system is involved in erection, orgasm, and tumescence. The parasympathetic nervous system is primarily involved in sustaining and maintaining an erection, which is derived from S2-S4 nerve roots.

While pills for ED are convenient, some men sustain stronger erections by injecting medication directly into the penis. Drugs approved for this purpose work by widening the blood vessels, causing the penis to become engorged with blood. Another option is inserting a medicated pellet into the urethra. The pellet can trigger an erection within 10 minutes.


Other hormone levels: Measurement of other hormones beside testosterone (luteinizing hormone [LH], prolactin level, and cortisol level) may provide clues to other underlying causes of testosterone deficiency and erectile problems, such as pituitary disease or adrenal gland abnormalities. Doctors may check thyroid levels in some individuals as both hypothyroidism (low thyroid function) and hyperthyroidism (overactive thyroid function) can contribute to erectile dysfunction.
With an inflatable implant, fluid-filled cylinders are placed lengthwise in the penis. Tubing joins these cylinders to a pump placed inside the scrotum (between the testicles). When the pump is engaged, pressure in the cylinders inflate the penis and makes it stiff. Inflatable implants make a normal looking erection and are natural feeling for your partner. Your surgeon may suggest a lubricant for your partner. With the implant, men can control firmness and, sometimes, the size of the erection. Implants allows a couple to be spontaneously intimate. There is generally no change to a man's feeling or orgasm.
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