IQI4 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY II 



and the thoroughness of the procedures such as tidal 

 drainage designed to prevent distention or shrinkage 

 of the bladder. 



Extreme hypertonicity (climbing tonus cur\e) 

 occurs as an intermediate or late stage after spinal 

 transection and, according to some, as the final 

 state after interruption of the sacral reflex arc (fig. 

 ii). The steeply rising tonus limb is interrupted by 

 frequent, but feeble, brief contractions. In spinal 

 transection cases, tonus becomes more normal when 

 the micturition reflex becomes more normal. 



FIG. II. .-Xutonomous neurogenic bladder dysfunction from 

 sacral root damage. Note the frequent small contractions super- 

 imposed on steeply ascending tonus limb. [From McLellan 

 (20).] 



In man, marked hypertonia has not been analyzed 

 as thoroughly as atonia. However, figure i2 shows 

 that a moderate degree of hypertonia (20 cm of 

 H2O) changed after administration of TEA only by 

 a slight shift to the right, probably the result of a 

 previous cystometric determination. There is there- 

 fore no evidence that hypertonia is neural in origin. 

 Unfortunately, the behavior of experimental or 

 clinical hypertonia has not been studied by repeated 

 cystometrograms. Figure 1 2 suggests that repeated 

 filling in the absence of micturition decreases the 

 tonus. Although the mechanism is less certain, the 

 association of small frequent micturitions with hyper- 

 tonia suggests that it is a physical change secondary 

 to the altered micturition reflex. Similar ascending 

 tonus curves are seen experimentally in two circum- 

 stances, a) after chronic decentralization of the blad- 

 der by pelvic nerve section, when frequent abortive 

 muscular contractions are acting against the re- 

 sistance of the internal sphincter, and b) when the 

 ureters are e.xteriorized (5, 34). 



HIGHER CONTROL OF MICTURITION 



The prevailing clinical view of the micturition 

 reflex in man has been developed and sustained with 

 little regard for the results of laboratory experiments. 

 The immediate agent in micturition is a spinal re- 

 flex employing the sacral segments. Clinicians con- 

 sider the cereijral control to be purely inhibitory and 

 think of micturition itself as an unleashing, or dis- 

 inhibition, of the spinal reflex. Altogether, clinical 

 thought on bladder dysfunction after spinal cord 

 lesions has undergone a remarkable evolution. Prior 

 to World War I, Bastian's law ("complete areflexia is 

 a criterion of complete spinal transection") included 

 the bladder. Between the two wars, automatic 



FIG. 12. Left. Diagram showing an 

 elevated Segment II of an 'uninhibited 

 neurogenic bladder' in man. Right. 

 .^fter tetraethylammonium bromide, 

 the micturition contractions disappear 

 but the hypertonus persists. [From 

 Nesbit & Lapides (26).] 



100 200 300 400 

 BLADDER VOLUME CC 



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 TEAB 



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