One of the most devastating complications of multiple sclerosis is the loss of sexual function. This is particularly difficult in young adulthood, when the diagnosis of MS is commonly made. Sexual dysfunction typically is reported more in persons with greater functional disability. However, there are reports of sexual complaints as the presenting symptoms of MS. Sexual dysfunction is common in MS. In women with MS, sexual dysfunction occurs in 56-90% of patients in various series. In all the published literature, the rate of dysfunction increases with increasing overall functional disability.
Many persons with MS do not realize that sexual changes can be a result of neuropathology. Sexual dysfunction in MS is commonly believed to be a result of the psychological effects of having a chronic disease, or a result of medication used to treat other symptoms of MS. However, there are several studies suggesting that a primary etiology of the sexual dysfunction is a result of disruption of genital somatosensory tracts, either by demyelination or axonal loss. Branches of the pudendal nerve are intricately involved with the regulation of sexual function, and when disrupted, there is resultant sexual dysfunction. Furthermore, MS lesions in the brain can also affect sexual function, typically with loss of sexual responsiveness as well as decreased libido.
Secondary causes of sexual dysfunction in persons with MS can be related to medication use, particularly those that affect the central nervous system. These can include antidepressants, muscle relaxants (baclofen, tizanidine), narcotic and non-narcotic pain medications such as tricyclic antidepressants (imipramine, amitriptyline) and anti-epileptics (gabapentin). Many of these medications are taken by persons with MS to help with symptom management, but these medications alone and in combination often contribute to decreased sexual responsiveness and function.
One of the most common symptoms of MS is fatigue, which is a major cause of disability. The fatigue is profound, and is a major deterrent to sexual responsiveness and desire. If the patient has impaired mobility or significant lower extremity spasm, that can also preclude effective sexual intercourse. Pain is another debilitating symptom of MS, and the presence of chronic and/or intermittent debilitating pain can affect sexual function.