The neurologic pathways required for erection originate in the cerebral cortex where visual, auditory, and psychic stimuli are processed, and in the pudenal nerve, an afferent nerve that transmits tactile sensations from the genitals to the sacral segments of the spinal cord and cortex. Efferent signals from the spinal cord pass along the pelvic parasympathetic nerves and dilate the corporal vessels. The specific neurotransmitters have not been fully defined; acetylcholine, and perhaps vasoactive intestinal peptide, appears to be important. There are many causes of neurogenic impotence. Anything that disrupts neural pathways or blocks neurochemical transmission will have an adverse effect on erection. Psychologic factors probably interfere with erection by inhibiting corticosacral efferent pathways.
Malleable implants usually consist of paired rods, inserted surgically into each of the corpora cavernosa. The rods are stiff, and to have an erection, one bends them up and then when finished with intercourse one bends them down. They do not change in length or width. The malleable implants are the least mechanical and thus have the lowest risk of malfunction. However, also have the least "normal appearance."
Yeah, because in some cases, things had settled down after the guy couldn't get it up any longer and the wife might even have been relieved. Typically, at the stage of life when ED hits, many women are in menopause and have vaginal dryness and pain, which could especially be a problem after a long period of no intercourse because of the guy's ED. And so when he suddenly wants to have intercourse like a 20-year-old every day after taking Viagra, it's the last thing the wife wanted. Or as has happened in some cases, the wife thinks the erection is "fake" -- it's just "chemical" and doesn't really represent his attraction for her. Any excuse to avoid vaginal pain and dryness problems, if not just plain disinterest in sex.
Although not proven, it is likely that erectile dysfunction can be prevented by good general health, paying particular attention to body weight, exercise, and cigarette smoking. For example, heart disease and diabetes are problems that can cause erectile dysfunction, and both are preventable through lifestyle changes such as sensible eating and regular exercise. Furthermore, early diagnosis and treatment of associated conditions like diabetes, hypertension and high cholesterol may prevent or delay erectile dysfunction, or stop the erectile dysfunction from getting more serious.