Sexual problems associated with neurological diseases
(Neurosexology)
European Federation of Neurological Societies Task Force on Neurosexology*.
Lundberg PO Swash M, Vodusek D B
Correspondence to
P O Lundberg
Department of Neuroscience: Neurology
UniversityHospital
Uppsala SE-751 85
Sweden
Tel + 46 18 611 50 26
Fax + 46 18 611 50 27
E-mail: PO.Lundberg@neurologi.uu.se
*The following text is based on Guidelines for Neurologists about Sexual problems associated with neurological diseases (Neurosexology) compiled by the members of the European Federation of Neurological Societies Task Force on Neurosexology published in 2001. The text has been revised, condensed and updated. Members of the task force has in recent years published a number of reviews on the topic of neurosexology (Lundberg 1980, 1992, Lundberg 1997a, 1999, 2001, 2005, 2006, Lundberg et al 2000, Ertekin 1998, Vodusek 1998, Vodusek & Fowler 1999, Ghezzi 1999, Fugl-Meyer et al 1999, Vodusek et al. 2005), Further details on clinical neurosexology can be found in these reviews.
Abstract
Sexual disorders, such as loss of sexual desire, erectile dysfunction, decreased lubrication, changes in arousal, disturbances of ejaculation and orgasm are common but often neglected by neurologists. However, they significantly impact on quality of life, and may be early features of a neurological disorder. This review is compiled following a literature search up to including 2005. It includes data on the pathophysiology of sexual function, impaired sexual function in the major neurological disorders, and recommendations for clinical investigation and treatment.
The value of the sexual history and neurological examination, which should include the sacral segments, is stressed. Additional testing is not routinely recommended. The majority of neurological patients with sexual dysfunction will respond to treatment. Sexual counseling I san important aspect of management, which should follow the headings of Permission, Limited information, Specific suggestion and Intensive treatment (PLISSIT). For erectile dysfunction oral phosphodiesterase type 5 inhibitors are effective in neurological disorders, but should be used with caution in hypertensive patients. Intracavernous injection therapy with vasoactive drugs may be useful when oral agents are ineffective or contra-indicated.
Introduction
The normal sexual response is traditionally described as comprising four different phases (Masters & Johnson 1966): Excitement, Plateau, Orgasm and Resolution. According to this model sexual desire is not a phase in itself. Kaplan (1974) suggested a three phase model: Desire, Excitement and Orgasm (Lue et al 2004).
To the neurologist the sexual response involves a series of neurally controlled phenomena occurring in a hormonally defined milieu. The different components; viz, motivation, arousal, genital reactions (erection, lubrication, emission, ejaculation) and orgasm have different neuroanatomical, neurophysiological, neurochemical, and neuropsychological dimensions. Little is known concerning specifically female sexual dimensions. Genital components of sexual function are inevitably the focus of discussion in neurological disorders. Nonetheless, sexual responses have a major psychological dimension, and they are dependent on neuroendocrinological factors. The male erection has to be firm enough for vaginal penetration, and maintained throughout intercourse to bring about ejaculation, which in turn should deliver sperm to the uterine cervix (Basson et al 2004, Goldstein et al 2004, Meston et al 2004).
Basic science
Genital innervation is both somatic and autonomic. Somatic sensory afferents deliver information on tactile sexual stimuli to the sacral spinal cord, and can induce local sexual responses (vascular-erectile and glandular). Sensory information projects to suprasacral regions which are also important in sexual awareness and excitation. The erectile response is initiated by parasympathetic efferents travelling through the pelvic plexus and the greater and lesser cavernosal nerves. Blood flow in the penile artery increases. Smooth muscles lining the cavernosal sinuses in the penis relax. Helicine arterioles branching from cavernosal arteries selectively shunt blood flow to the lacunar spaces of the cavernosal bodies which fill with blood; subtunical venules become compressed. Intracorporeal pressure increases and then stabilises at a level approximating systolic blood pressure causing penile tumescence and rigidity. Continued parasympathetic activity maintains this erection (Smith & Bodner 1993). This parasympathetic pathway is, however, not the only proerectile pathway: erections are observed in humans and experimental animals after lesions of sacral cord segments and pelvic nerves, probably througha pathway involving the hypogastric nerves. The role of the hypogastric parasympathetic nerves in human penile ersction is not fully understood.
Continued stimulation eventually induces orgasm with seminal emission, rhythmic phasic contractions of perineal and pelvic floor muscles (ejaculation). Actually emission begins during arousal (Mitsuya et al 1960). Ejaculation requires sympathetic outflow from T11-L2 segments travelling through the hypogastric plexus, and along pelvic and pudendal nerves (Giuliano et al 1995). Animal experiments have shown extensive cross-innervation of the sympathetic nervous system (Kihara & Degroat 1997). Sympathetic activity causes smooth muscle contraction: in seminal vesicles, vas deferens, and prostate – to deliver seminal fluid to posterior urethra; in the bladder neck – to prevent retrograde ejaculation; in the corpora cavernosa – to cause detumescence. The latter “antierectile” activity is probably inhibited during erection through spinal coordination of reflex action. In the periphery the main proerectile transmitter is nitric oxide, which is co-localized with VIP (vasoactive intestinal peptide) and acetylcholine. The main anti-erectile neurotransmitter is probably noradrenaline (Giuliano et al 1995). Although the predominant neural control of the male accessory sexual organs is sympathetic (adrenergic and purinergic), the secretion of seminal fluid is under parasympathetic control (Hoyle et al 1994). Appropriate sensory stimulation leading to erection and orgasm is not necessarily purely genital, and erections caused by stimuli delivered through cranial nerves might also be reflexive, although this is usually subsumed under “psychogenic” (Sachs 1995). Mental imagery is the “real” psychogenic descending activating stimulus of these spinal cord-integrated reflex responses, but very little is known about these evidently important mechanisms.
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