Erections are more complicated than you think. Your brain, nerves, heart, blood vessels, and a whole lot of hormones have to work together perfectly or nothing happens. It’s a lot to ask, and sometimes things break down. And while ED happens to most guys at some point in their lives, erectile dysfunction isn’t something you can just ignore and hope it goes away.

SD in MS can be classified into three categories. Primary SD is due directly due to MS-related neurological deficits, secondary SD is related to physical impairments and symptoms or drugs used for MS treatment, and tertiary SD is due to the psychological, social and cultural problems attributed to MS (38). These classifications are important, and underscore the importance of addressing all the issues leading to SD not just the neurologic impairment.


This category of treatments includes external vacuum therapies: devices that go around the penis and produce erections by increasing the flow of blood in, while constricting the flow out. Such devices imitate a natural erection, and do not interfere with orgasm. External vacuum therapy mechanisms are approximately 95 percent successful in causing and sustaining an erection. All are portable, and costs range between $200-$500, covered under most insurance plans and Medicare Part B.
It is important to understand that ED is frequently, if not usually, directly related to endothelial dysfunction, and that the release of NO by the vasculature of the penile arteries is directly related to the function of intact, healthy endothelium. In the face of endothelial dysfunction, the process of erection fails to occur in a normal fashion.16
Alprostadil is a potent vasodilator and smooth muscle relaxant identical to the naturally occurring PGE1. PGE1 binds with specific receptors on smooth muscle cells and activates intracellular adenylate cyclase to produce cAMP, which in turn induces tissue relaxation through a second messenger system (96). PGE1 is the only FDA approved form of intracavernosal therapy and is available commercailly as EDEX, or Caverject. Its efficacy was demonstrated in several clinical trials where the rate of responders ranged from 40% to 80% (97,98). The most common adverse event is penile pain, which is not related to the injection of the medication itself. In men with prolonged use the pain is usually self-limited (99).
Many experts believe that atrophy, a partial or complete wasting away of tissue, and fibrosis, the growth of excess tissue, of the smooth muscle tissue in the body of the penis (cavernous smooth muscle) triggers problems with being able to maintain a firm erection. Poor ability to maintain an erection is often an early symptom of erectile dysfunction. Although the condition is called venous leak, the real problem is not with the veins but malfunction of the smooth muscle that surrounds the veins. The end result is difficulty with maintain a firm erection (losing an erection too quickly) that is now believe to be an early manifestation of atherosclerosis and vascular disease.
For many men, stopping smoking is an erectile dysfunction remedy, particularly when ED is the result of vascular disease, which occurs when blood supply to the penis becomes restricted because of blockage or narrowing of the arteries. Smoking and even smokeless tobacco can also cause the narrowing of important blood vessels and have the same negative impact. 

In some cases, ED can be a warning sign of more serious disease. One study suggests ED is a strong predictor of heart attack, stroke, and death from cardiovascular disease. The researchers say all men diagnosed with ED should be evaluated for cardiovascular disease. This does not mean every man with ED will develop heart disease, or that every man with heart disease has ED, but patients should be aware of the link.

Side effects include lightheadedness, fainting, priapism, urethral bleeding (intraurethral), dyspareunia in the partner (intraurethral), hematoma (intracavernosal) or penile curvature secondary to scar (intracavernosal). Efficacy of intraurethral alprostadil has been demonstrated to be around 50% ("able to have intercourse") in randomized controlled trials.31,32 For intracorporeal injection, typically alprostadil is tried alone, or compounded with papaverine (nonspecific phosphodiesterase inhibitor that increases intracellular cyclic adenosine monophosphate and cGMP) and/or phentolamine (competitive, non-selective alpha1- and alpha2-adrenoreceptor blocker). Pinsky et al33 reported an extensive review of the benefits and drawbacks of the combinations of these drugs.

Adverse effects related to PDE5i use with mild-moderate and transient (58). Furthermore, side effects usually attenuate if use is not discontinued. Autonomic dysreflexia, a life-threatening phenomenon characterized by bradycardia, hypertension, facial flushing and headaches associated with SCI lesions above T6, has not been reported with use. However, hypotension leading to dizziness in individuals treated with sildenafil has been noted with high thoracic and cervical levels of injury (72). No adverse events were noted within the study; however, the dizziness was reported by use of sildenafil 50 mg in the cervical LOI and 100 mg in the thoracic LOI patients. Headache is the most reported side effect of all PDE5i, followed by dyspepsia and flushing. Priapism, and death have not been reported after use of PDE5i by SCI patients.
If you can't take one of these oral medications, your physician may have you try Caverject (alprostadil for injection), a hormone that you inject into your penis using a fine needle, or Muse (alprostadil urogenital), a tiny suppository that you insert into the tip of the penis. Both of these will bring on an erection within five to 15 minutes without sexual stimulation.
For best results, men with ED take these pills about an hour or two before having sex. The drugs require normal nerve function to the penis. PDE5 inhibitors improve on normal erectile responses helping blood flow into the penis. Use these drugs as directed. About 7 out of 10 men do well and have better erections. Response rates are lower for Diabetics and cancer patients.
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