In addition, damage to erectile tissue can be the cause of erectile dysfunction . Disturbances of one factor alone, but also the combination of different factors, can limit or cancel the ability to erect. Studies of earlier years, which put the proportion of erectile dysfunction caused by psychogenic factors at 85-90% of cases , must now be corrected to the extent that various authors state the proportion of primary organic causes between 30 and 85%, of which, in turn, vascular causes are said to underlie 50-80% of cases [2, 6]. Vascular disorders of erection can be caused arterially or in the venous area.
Fig. 1.6 Major factors influencing erection.
In vascular-arterial causes, there is a reduction of arterial inflow, due to arteriosclerotic processes or congenital or acquired angiopathies. Patients with vascular-venous erectile dysfunction show an increase in venous outflow from the corpus cavernosum, the pathologic-anatomic substrate of which ultimately remains unclear. Neurogenic dysfunction can be expected in up to 10%  of the patient and is commonly found clinically in diabetic neuropathies. It should be noted restrictively that vegetative neuropathies are insufficiently diagnosable, and the exact proportion of neurogenic causes should therefore hardly be precisely determinable.
The clinically relatively rare hormonally induced erectile dysfunction (up to approx. 5% of patients) is based either on testosterone deficiency or hyperprolactinemia. Iatrogenically induced erectile dysfunction, as found after radical pelvic surgery, is usually due to damage to nervous structures or lesions of accompanying vessels. Chronic intoxication by alcohol, drugs or commercial poisons (lead, hydrocarbons) can also cause erectile dysfunction . Numerous pharmaceuticals can affect human sexual behavior and lead to disorders of libido, erection, and ejaculation. These are mostly drugs that have central nervous targets, influence the autonomic nervous system, interfere with sex hormone regulation, or decrease peripheral blood flow. In particular, sex hormones and drugs with sex hormone-like effects, psychotropic drugs, and antihypertensives are known to cause erectile dysfunction (Table 1.2).
In all organic disorders, it must always be kept in mind that a primarily organic erectile dysfunction can, over time, cause a secondary psychotrauma (fear of failure) and thus a vicious circle of sexual dysfunction. The high number of pronounced psychopathological abnormalities even in patients with primarily organic disorders points to the need for a psychosomatic view of erectile dysfunction , which may necessitate the involvement of a psychiatrist even in cases of clear organogenesis to ensure the success of therapy.
Table 1.2. Drugs with negative influence on erection.
Central nervous effects: