98 URODYNAMICS AND VOIDING DYSFUNCTION
Firouz Daneshgari M.D.

1. What is urodynamics?

Show answer
Urodynamic studies assess the functional aspects of the storage and emptying ability of the lower urinary tract (LUT). The principles of urodynamic studies originated from hydrodynamics. The components of urodynamic studies are cystometrogram, leak point pressures, urethral profile pressures, pressure-flow studies, uroflowmetry, and electromyography. These studies have evolved into videourodynamics with the addition of fluoroscopy (i.e., video).

2. What is uroflowmetry?

Show answer
Uroflowmetry is the measurement of voided urine (in milliliters) per unit of time (in seconds). The important elements of the test are voided volume (which should be > 150 mL), maximum flow rate (Qmax), and the curve of the flow (which should be bell shaped). The normal Qmax is > 20 mL/sec in men and > 25 mL/sec in women.

3. What is benign prostatic hyperplasia (BPH)?

Show answer
BPH is benign enlargement of the prostate gland that may lead to bladder outlet obstructive symptoms in men. These symptoms have recently been termed lower urinary tract symptoms (LUTS).

4. What is an American Urological Association (AUA) symptom score?

Show answer
It is a self-reported questionnaire developed and popularized by the AUA for the assessment of bothersome LUTS in men. This questionnaire has seven questions with a maximum score of 35. The higher the score, the more severe and bothersome the symptoms. The AUA symptom score has become an index for both the diagnosis and evaluation of treatment outcome in patients with LUTS.

5. What are the main functions of the LUT?

Show answer
Storage and emptying of urine are the main functions. For practical purposes, all symptoms of LUT dysfunction can be categorized into the malfunction of either storing or emptying ability.

6. What are the control mechanisms for LUT function?

Show answer
The control mechanisms for LUT function are recognized as central and peripheral. The central control mechanisms consist of the cortical portion of the frontal lobe of the brain and pontine micturition center. The peripheral control mechanisms include the thoracic sympathetic and lumbar parasympathetic innervation and neuromuscular apparatus of the LUT organs.

7. What is the role of the autonomic nervous system in the function of the LUT?

Show answer
Sympathetic fibers, which originate from the T10-L2 portion of the spinal cord, innervate the bladder neck and proximal urethra. These fibers mostly control the contraction of the proximal urethra or bladder neck and relaxation of the bladder, which results in storage of urine. The parasympathetic fibers, which originate primarily from the S2-S4 portion of the spinal cord, innervate the bladder body. The parasympathetic innervation allows contraction of the bladder smooth muscle, leading to bladder emptying.

8. What is the role of the somatic nervous system in the function of the LUT?

Show answer
Voluntary control of the striated muscle of the external urinary sphincter is controlled by the somatic nervous system. Somatic fibers are conveyed to the sphincter by the pudendal nerve.

9. What is bulbocavernosal reflex?

Show answer
Bulbocavernosal reflex tests the integrity of peripheral neurologic control of the LUT. This reflex is elicited by stimulation of the glans penis in men or the clitoris in women, which causes contraction of the external anal sphincter or bulbocavernosus muscle. Alternatively, the reflex may be stimulated by pulling the balloon of a Foley catheter against the bladder neck. This reflex is present in all normal men and in approximately 70% of normal women. Absence of this reflex in a man is strongly suggestive of a sacral neurologic lesion.

10. What is the most common cause of incontinence in the geriatric population?

Show answer
The most common are transient causes, mostly external, that disrupt the fragile balance of LUT function in elderly patients and cause urinary incontinence. These causes can be recalled with the mnemonic DIAPPERS:

* Delirium
* Infections
* Atrophic urethritis or vaginitis
* Pharmaceuticals
* Psychological (depression)
* Endocrine (hypercalcemia, hyperglycemia)
* Restricted mobility
* Stool impaction

KEY POINTS: URODYNAMICS AND VOIDING FUNCTION

1. Uroflowmetry is the measurement of voided urine (in milliliters) per unit of time (in seconds).
2. Benign prostatic hypertrophy is benign enlargement of the prostate gland that may lead to bladder outlet obstructive symptoms in men.
3. The sacral roots involved in micturition physiology are S2-S4.

11. What is spinal shock? What type of urinary dysfunction does it cause?

Show answer
Spinal shock is the loss of contractility of the smooth muscle below the level of spinal cord injury, leading to difficulty in bladder emptying or urinary retention. This phenomenon may last from hours to several months with a high chance of reversibility if the spinal cord injury is not permanent.

12. What is autonomic dysreflexia? How is it treated?

Show answer
Autonomic dysreflexia results from systematic outpouring of sympathetic discharge, as in patients with spinal cord lesions at or above the T6 level. This dysreflexia is triggered by distention of the bladder or other stimulus of the bowel or LUT. It is manifested by hypertension, bradycardia, hot flush, sweating, and headache. Initial treatment consists of removal of the stimulus, such as emptying the bladder and placing the patient in a sitting position. Nifedipine or nitroprusside may be used as either prophylaxis or treatment of severe episodes. This condition may lead to significant cerebrovascular complication if untreated.

13. What type of bladder dysfunction is seen in diabetic patients?

Show answer
Diabetic cystopathy is manifested primarily as atonic bladder with difficulty in emptying caused by impaired contractility of the bladder or detrusor muscle.

14. What type of bladder dysfunction is seen in patients with multiple sclerosis (MS)?

Show answer
Urgency (83%), urge incontinence (75%), detrusor hyperreflexia (62%), and detrusor sphincter dyssynergia (25%) are among the most common LUT symptoms in patients with MS. Variation in symptoms depends on the site of involvement by MS. Involvement of pontine pathways (tegmentum) is associated with a much higher rate of urinary symptoms.

15. Which sacral roots control the micturition physiology?

Show answer
S2-S4.
16. What are the causes of urinary retention after abdominal or pelvic surgery? Show answer
They are injuries or disruption of pelvic plexus innervation to the LUT.

17. What is Ogilvie’s syndrome?

Show answer
Acute massive dilatation of the cecum and ascending and transverse colon without organic obstruction is known as Ogilvie’s syndrome. This syndrome can be seen in pelvic urologic surgeries, possibly as a result of an imbalance in parasympathetic stimulation of the colon.

18. What is reflex versus psychic erection?

Show answer
Erection after local stimulation is termed reflex erection. The afferent nerves for reflex erection run in the pudendal nerves, and the efferent fibers are found in the S2-S4 parasympathetic outflow. The psychic erection is caused by stimulation of cerebral erotic centers. The afferent stimuli for psychic erection travel through the thoracolumbar sympathetic outflow and sacral parasympathetic fibers.

References
WEB SITE
http://www.transplantation-soc.org
BIBLIOGRAPHY
1. Bross S, Braun PM, Michel MS, et al: Preoperatively evaluated bladder wall tension as a prognostic parameter for postoperative success after surgery for bladder outlet obstruction. Urol 61:562-566, 2003. Medline Similar articles Full article
2. Holtgrewe HL: Current trends in management of men with lower urinary tract symptoms and benign prostatic hyperplasia. Urology 51(suppl 4A):1-7, 1998.
3. Litwiller SE, Forhman EM, Zimmern PE: Multiple sclerosis and the urologist. J Urol 161:743-757, 1999. Medline Similar articles Full article
4. Mochrer B, Carey M, Wilson D: Laparoscopic colposuspension: A systematic review. Br J Obstet Gynaecol 110:230-235, 2003.
5. Resnick NM, Yalla SV: Geriatric incontinence and voiding dysfunction. In Walsh PC, Retik AB, Vaughan ED, et al (eds): Campbell’s Urology, 7th ed. Philadelphia, W.B. Saunders, 1998.
6. Steers WD, Barrett DM, Wein AJ: Voiding dysfunction, diagnosis, classification and management. In Gillenwater JY, Grayhack JT, Howards SS, Duckett JW (eds): Adult and Pediatric Urology, 3rd ed. St. Louis, Mosby, 1996.
7. Wang CC, Yang SS, Chen YT, Hsieh JH: Videourodynamics identifies the causes of young men with lower urinary tract symptoms and low uroflow. Eur Urol 43:386-390, 2003.