2. Medical, social, and functional history.
Urodynamics is defined as the study of normal and abnormal factors in the storage, transport and emptying of urine from the bladder and urethra by an appropriate method. The water fill urodynamic study has a filling phase, where water is being infused into the bladder. Bladder sensation, bladder capacity, bladder wall compliance and bladder stability can be evaluated. In the voiding phase (when a person is told to void, or person with neurogenic bladder has an uninhibited contraction and voiding begins.) evaluate Leak point pressure, maximum voiding pressure, urethral sphincter activity, flow rate, voided value and PVR. Initial testing is often done 3-6 moths post injury or whenever bladder is out of spinal shock. Figure 13 shows a water fill urodynamic set-up and figure 14 shows a schematic representation of various voiding patterns. A normal urodynamic study will show that at bladder capacity (400-500 ml), bladder voiding is consciously initiated and the bladder contracts generating intravesical pressures of 40-80 cm H20; the external sphincter relaxes in a coordinated fashion to allow for complete bladder emptying. Figure 15a and 15b demonstrate urodynamic study characteristics of detrusor hypereflexia with sphincter dysynergia, and detrusor and urethral sphincter areflexia, respectively.
Figure 13.Water fill urodynamic set-up. Simultaneous monitoring of various urodynamic parameters is shown. Intravesical pressure minus intrabdominal pressure will produce the detrusor pressure (Pdet). (A) Intravesical pressure (Pves), (B) Urethral sphincter pressure (Pur), (D) Intrabdominal pressure (pabd).
Figure 14.Schematic representation of various voiding patterns. (A) Normal; (B) Uninhibited contractions occur with filling. The sphincter is attempting to inhibit contractions. Patient has a normal voiding phase; (C) No bladder contractions. Rises in bladder pressure are due to rises in abdominal pressure; (D) Uninhibited contractions occur with simultaneous sphincter contractions (i.e. detrusor sphincter dysnergia). Note. Pabd, intrabdominal pressure; Pur urethral sphincter pressure; Pves, intravesical pressure.
Figure 15a. Urodynamic study characteristic of detrusor hypereflexia with sphincter dysynergia. Bladder contraction occurs at low bladder volumes. The urethral sphincter contract as well instead of relaxing during bladder contraction, resulting in extremely high intravesical pressures (>100 cm H20) and incomplete bladder emptying.
Figure 15b. Urodynamic study characteristic of detrusor and urethral sphincter areflexia. Minimal or no bladder contractions are generated, even with bladder filling to high bladder volumes (> 500 ml) There is minimal urethral sphincter activity during bladder filling.
Table 2. Bladder Dysfunction based on Lesion Location
|Lesion Location||Urodynamic Study Pattern|
|Rostral to pons||Detrusor hyperreflexia with coordinated sphincters|
|Between pons and sacral spinal cord||Detrusor hyperreflexia with sphincter dyssnergia|
|Sacral spinal cord||Detrusor and sphincter areflexia; normal detrusor function with areflexic sphincter|
|Cauda equina or peripheral nerves||Detrusor and sphincter areflexia|