Erectile dysfunction is one of the most common symptoms of multiple sclerosis in men, affecting 23 to 91 percent of men. Multiple sclerosis is a disease characterized by progressive nerve damage. When the nerves responsible for erection are affected, erectile dysfunction may occur or worsen, resulting in impaired stimulation and/or arousal. Erectile dysfunction is a common condition that can affect men of any age, but is more common in those over 65. Erectile dysfunction can be caused by a variety of factors or lifestyle, such as stress, high blood pressure, obesity, diabetes, excessive alcohol use, and certain medications. By the age of 40, approximately 40% of men may be affected by erectile dysfunction, regardless of multiple sclerosis. This percentage can increase to almost 70% by age 70. The way erectile dysfunction affects men can manifest differently and include: An inconsistent ability to achieve an erection; Dissatisfaction with the size or hardness of the penis during erection; Presence of an erection of short duration; Requiring too much time and/or stimulation to achieve an erection; Causes Related to Multiple Sclerosis An erection occurs when signals from the brain cause the muscles of the penis to relax, allowing blood to flow into the two corpora cavernosa (cavernos) on the underside of the penis. The increased blood supply causes the penis to swell and become hard. Erections occur in response to sexual arousal or physical stimulation of the penis. These are important differences because they involve two different neurophysiological mechanisms: In an erection that occurs in response to erotic thoughts, touch, or visual cues, information is processed by the brain and nerve impulses are sent down the spinal cord to produce an erection; Erections that occur as a result of genital stimulation use nerves in the lower part of the spinal cord and basically bypass the brain. In multiple sclerosis, nerve damage is caused by a process called demyelination, in which the immune system attacks and removes the insulating membrane surrounding the nerve, called the myelin sheath. When this happens, the points of communication between the nerves can be severely affected. Depending on where the demyelination occurs, the cause and symptoms of erectile dysfunction can vary. Some men, for example, can achieve an erection in response to physical but not erotic stimulation, or vice versa. This appears to be particularly true for younger men with multiple sclerosis who have no other known contributing factors to erectile dysfunction. In other cases, the condition may be more pronounced. In such a case, multiple sclerosis is possible to be either the main cause of the erectile dysfunction or simply a secondary factor,compounding the existing problem. References: 1. Balsamo R, Arcaniolo D, Stizzo M, et al. Increased risk of erectile dysfunction in men with multiple sclerosis: an Italian cross-sectional study 2. Yafi FA, Jenkins L, Albersen M, et al. Erectile dysfunction 3. Krzastek SC, Bopp J, Smith RP, Kovac JR. Recent advances in the understanding and management of erectile dysfunction