Impotence is now more commonly referred to as erectile dysfunction. Impotence may be due to local end-organ disease, dysfunction of the peripheral nerve pathways, disease of the spinal cord or brain, pituitary and other endocrine disorders, and supratentorial disorders. Thus, recall of the various causes is based on both anatomy and physiology.
End-organ disorders: These include phimosis, paraphimosis, prostatitis, prostate carcinoma, and Peyronie disease. The blood supply to the penis may be affected by arteriosclerosis of the dorsal penile arteries or the terminal aorta (Leriche syndrome).
Peripheral nerve disorders: Diabetic neuropathy is a common cause in this category, but alcoholic neuropathy and other neuropathies may occasionally cause impotence.
Spinal cord disorders: Transverse myelitis, poliomyelitis, compression fractures, spinal cord tumors, multiple sclerosis, and tabes dorsalis are important disorders to be considered here.
Disorders of the brain: In addition to general paresis, brain tumors, vascular occlusions, and arteriosclerosis, degenerative diseases such as Alzheimer disease, senile dementia, and Schilder disease will cause impotence.
Pituitary and other endocrine disorders: Impotence is found in pituitary tumors, acromegaly, testicular atrophy from hemochromatosis, mumps, Klinefelter syndrome, Cushing disease, and hypothyroidism. Hyperprolactinemia is associated with impotence.
Supratentorial disorders: Recent studies suggest that less than 10% of cases of impotence are caused by psychiatric disorders. After years of marriage and intercourse with the same sexual partner, one’s libido may decline considerably. The first time the male patient has trouble reaching an erection, he begins to believe he is “over the hill.” If he should happen to acquire a young mistress, he may find convincing proof that his impotence is psychologic.
Sometimes, in search of variety in his sexual life, a married man may decide to find a new sexual partner. When the moment of truth arrives, he may be unable to get an erection because of the associated guilt involved.
Premature ejaculation is common under these circumstances also. After his first failure, the fear of a repeated performance may make him impotent not only in extramarital relations but also in marital relations.
Young men, whether married or unmarried, may “fall into impotence” quite by accident because of alcoholic intoxication. As Shakespeare correctly surmised, “alcohol provokes the desire, but it takes away the performance.” Under the influence of alcohol, the inspired lover may fail miserably. When sober once more, he may begin a pattern of failure to get an erection simply because of the fear that it will happen again and he will be embarrassed beyond belief.
Some other supratentorial causes of impotence are endogenous: depression, schizophrenia, latent homosexuality, repressed hostility toward the partner, and fear of pregnancy. It is important to note that all of the above psychologic causes may occur in the female patient as well as the male. There are many more causes too numerous to mention in a book of this scope.
Approach to the Diagnosis
A history of drug or alcohol abuse is important. Many drugs can cause impotence, especially the antihypertensives. A careful examination of the external genitalia, the prostate, and secondary sex characteristics is essential. The laboratory workup may include a glucose tolerance test, blood testosterone, free testosterone, serum prolactin and cortisol levels, thyroid function studies, a spinal tap, a skull x-ray, and a chromosomal analysis. A nocturnal penile tumescence study is performed to rule out organic causes. If the physical examination is normal, it may be wise to administer psychometric tests or to refer the patient to a psychiatrist before doing an extensive endocrine and neurologic workup. A sympathetic physician may be able to find the supratentorial cause and cure it with a few long discussions with the patient. A female physician may have more success in this area than a male.
Other Useful Tests
Serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels (pituitary or gonadal insufficiency)
Sperm count (testicular atrophy)
Penile blood pressure (Leriche syndrome, arteriosclerosis)
Spinal tap (multiple sclerosis, neurosyphilis)
Computed tomography (CT) scan of the brain (pituitary tumor)
Testicular biopsy (testicular atrophy)
Cystometric studies (neurogenic bladder)
Doppler sonogram of dorsalis penis artery (arteriosclerosis)
Drug screen (drug abuse)
Interview of spouse
Nerve conduction velocity (NCV) and electromyogram (EMG) (peripheral neuropathy)
4-week therapeutic trial of antibiotics (chronic prostatitis)
Therapeutic trial of oral sildenafil or alprostadil injection
Case Presentation #54
A 56-year-old diabetic man complained of increasing erectile dysfunction. Physical examination revealed diminished dorsalis pedis and tibialis pulses in both lower extremities. Neurologic examination revealed glove and stocking hypesthesia and hypalgesia.
Question #1. Given your knowledge of anatomy and physiology, what is your differential diagnosis?
A neurologist is consulted. His examination discloses diminished femoral pulses and bruits over the femoral arteries and abdominal aorta.
Question #2. What is your diagnosis now?
(See Appendix B for the answers.)
Anatomy will serve us well in recalling the various causes of fecal incontinence. The pathway of voluntary control of this function begins in the cerebrum and travels through the brain stem, spinal cord, and nerve roots, to the “end organ,” which is the rectal sphincter.
Cerebrum: This should help recall the incontinence of Alzheimer disease, normal pressure hydrocephalus, and other causes of organic brain syndrome. It will also prompt the recall of the incontinence in functional psychosis and epilepsy.
Brainstem and spinal cord: This would bring to mind trauma, multiple sclerosis, transverse myelitis, syringomyelia, and brainstem and spinal cord tumors in which there is loss of voluntary control due to pyramidal tract damage.
Nerve roots: This should prompt the recall of cauda equina tumors, tabes dorsales, and spinal stenosis.
Rectal sphincter: Primary rectal sphincter incompetence leads to the release of small amounts of stool associated with anal fissures, hemorrhoids, and postoperative incontinence following a fistulectomy or episiotomy.
Approach to the Diagnosis
Before beginning an expensive diagnostic workup, pay attention to the history and physical examination. Is there a small volume of stool? Look for an anal fissure, hemorrhoids, or other causes of sphincter incompetence. If the incontinence is sporadic, look for organic brain syndrome, epilepsy, or functional psychosis. If the neurologic examination reveals pathologic or hyperactive reflexes in the lower extremities, consider a spinal cord or brain stem lesion. If there are hypoactive reflexes in the lower extremities, consider the possibility of cauda equina tumor or tabes dorsalis. Careful digital examination will often reveal a local cause. If the sphincter is tight, consider a spinal cord lesion. If it is flaccid, consider a lesion of the cauda equina or nerve roots.
Patients with signs of mental deterioration need a CT scan or MRI of the brain. Normal pressure hydrocephalus can be excluded by radioactive cisternography. Patients with hyperactive reflexes in the lower extremities need a CT scan or MRI of the suspected level of spinal cord involvement, whereas patients with hypoactive reflexes require an MRI of the lumbar spine or myelography. Anorectal manometry and defecography will assist in the diagnosis of anal and rectal sphincter dysfunction. A neurologist or gastroenterologist may need to be consulted.
Incontinence may be due to loss of voluntary control of urination, in which case neurologic disorders are usually the cause, or it may result from overflow of a distended bladder (overflow incontinence), in which case the cause may be bladder neck obstruction or a flaccid neurogenic bladder. Stress incontinence occurs on coughing or straining and is due to damage to the urethra or pelvic floor from pregnancy and delivery.
Loss of voluntary control: The neurologic causes include multiple sclerosis, normal pressure hydrocephalus, neurosyphilis, syringomyelia, encephalitis, cerebral arteriosclerosis, frontal lobe tumors and abscesses, senile dementia, and transverse myelitis from trauma or infection. The local causes are a cystocele (often following a hysterectomy) and a damaged urethral sphincter from prostatectomy.
Bladder neck obstruction: Benign prostatic hypertrophy, chronic prostatitis, prostate carcinoma, median bar hypertrophy, vesical calculus, and urethral stricture are important mechanical causes of obstruction.
Flaccid neurogenic bladder: Drugs such as atropine, tranquilizers, and anesthetics and diseases of the cauda equina and nervi erigentes such as diabetic neuropathy, poliomyelitis, tabes dorsalis, and cauda equina tumors will cause a flaccid neurogenic bladder with overflow incontinence.
Approach to the Diagnosis
First, exclude stress incontinence with a pad test. Perineal pads are weighed before and after walking and stress for 30 minutes. An increase in weight identifies urine loss. Catheterization and examination, smear, and culture of the urine are essential at the outset. Cystoscopy and cystometric studies are often needed. Surgical repair of a cystocele or a parasympathomimetic drug in cases of a flaccid neurogenic bladder and oxybutynin (Ditropan) for spastic neurogenic bladders may be all that is necessary. A neurologist and urologist often need to cooperate in the diagnosis and treatment of these unfortunate individuals.