PRIAPISM AND POSTPRIAPISM ERECTILE DYSFUNCTION

12 PATHOPHYSIOLOGY OF ERECTILE DYSFUNCTION

PRIAPISM AND POSTPRIAPISM ERECTILE DYSFUNCTION

Priapism may be defined as an involuntary erection that lasts for more than
4-6 h. The condition may be spontaneous orsecondary to intracavernous
pharmacotherapy. Spontaneous priapism may be idiopathic or associated with blood
disorderssuch as sickle cell anemia, leukemia or other malignancies (Figure
34).

After 4-6 h, a persistent erection usually becomes painful, but late
presentation is not uncommon because of embarrassment.Initial therapy
involves corporeal aspiration and injection of adrenergic vasoconstrictor
substances such as phenylephrine ormetaraminol (Aramine®). Because these
potent vasoactive agents frequently enter the circulation after intracorporeal
injection,blood pressure should be carefully monitored during therapy.

Although pharmacotherapy with aspiration and injection of vasoactive agents
is often successful within 6-12 h of onset ofpriapism, beyond that time
period the efficacy of any therapy is rapidly diminished. Initial high-flow
priapism is followed bylower flow and progressive deoxygenation of the
corpora. In these later cases, aspiration of the corpora reveals
darkdeoxygenated blood. Progressive ischemia to the intracorporeal smooth
muscle renders the helicine arteries and walls of thetrabecular spaces
progressively less capable of developing sufficient vasoconstriction necessary
to restore and maintainflaccidity.

The consequence of untreated priapism or priapism unresponsive to therapy is
the development of corporeal fibrosis. Thisresults in erectile dysfunction
which is difficult, and sometimes impossible, to treat. Even insertion of a
penile prosthesis maybe technically difficult in such cases because the
fibrosis renders dilatation of the corporeal space problematical.

PSYCHOGENIC CAUSES

Psychological causes were once widely assumed to be the predominant cause of
erectile dysfunction. However, if the correctdefinition of erectile
dysfunction is applied, namely, the persistent loss of penile rigidity in all
circumstances, thenpsychogenic erectile dysfunction proves to be less common
than its organic counterpart, especially in older men. Psychogenicerectile
dysfunction typically occurs in younger men, and is variable and often
associated with performance anxiety. Increasedsympathetic vasoconstrictor
tone and raised circulating norepinephrine levels are most probably involved.
Psychogenicfactors also come into play in other forms of erectile
dysfunction, as failure of erection itself induces anxiety, loss
ofconfidence and sometimes relationship difficulties. The conviction that an
erection will not develop when required, therefore,becomes a self-fulfilling
prophesy.