CENTRAL CONTROL OF THE BLADDER 



I219 



PONS 



FIG. 18. Left. Diagram illustrating the control of sacral micturition reflex by diff^erent levels of 

 neural axis, based on cystometric effects of successive removal of these controls by transections at 

 different levels. Plus sign indicates a facilitatory and minus sign, an inhibitory effect on pelvic nerve 

 preganglionic neurons. [From Tang (31).] Right. On a saggital section of the cat brain is projected 

 the loci of the hypothalamic (//), rostral midbrain (.\1) and rostral pontine (P) areas exerting 

 facilitatory ( + ) or inhibitory ( — ) effects on the micturition reflex. Diagram is based upon transec- 

 tions and stereota.xic lesions [From Tang & Ruch (33).] 



facilitation from brain-stem centers. The phrases 

 'faciUtated micturition' and "vesicle hyperrefle.xia' 

 would convey this better than the clinical phraseol- 

 ogy. That the lack of inhibition results from the 

 micturition reflex receiving impulses solel)' from the 

 pyramidal tract is certainly suspect since actisity in 

 other tracts inhibits the micturition reflex after in- 

 terruption of corticospinal tracts. 



From the fact that tiie bladder, like the antigra\ity 

 muscles, is subject to a play of facilitatory and in- 

 hibitory impulses from the brain stem and cereljral 

 cortex, it appears that the overreactive and the nor- 

 mally reactive bladder represent the retention of some 

 descending facilitatory pathways. This hypothesis is 

 required to explain spastic paraplegia after partial 

 cord lesions and in fact the spasticity of hemiplagia. 



AUTOM.\TIC BL.^DDER. SYNONO.VIY : NORM.'kL .\ND SP.ASTIC 

 REFLEX NEUROGENIC BLADDER, SL'PR-^NUCLEAR NEU- 

 ROGENIC BL..\DDER, 'cord' bl.adder. All are agreed 

 that in man, the status of the bladder following im- 

 mediately and for some days after complete transec- 

 tion of the spinal cord above the sacral segments is 

 one of complete arefiexia, although none has offered 

 an explanation of this fact. According to McLellan 

 (20), '"Detrusor activity is entirely reflex, micturition 

 being imperative or precipitate, and the ability for 

 its initiation may be lost." Bladder sensation is 

 abolished, although the patient may be aware of the 

 bladder contraction or of concomittant visceral 

 phenomena, flushing, sweating or piloerection. The 

 cystometrogram may approach normal in respect to 



capacity but not to complete emptying, a residuum 

 of 50 to 100 ml being typical. 



A subvariety of the automatic bladder (spastic 

 neurogenic bladder) is described by McLellan as "a 

 spastic, irritable, reflex neurogenic bladder emptying 

 completely at irregular short intervals by precipitate 

 micturition and characterized by a capacity of less 

 than 100 cc. There is usually no warning of evacua- 

 tion and little inhiljitory or voluntary control."' 

 This condition is often accompanied by spasticity of 

 the limbs. This category seems to overlap his first 

 one. Munro (23) describes a similar response as the 

 third, or hypertonic, stage preceding the develop- 

 ment of a more normal "reflex bladder.' The inad- 

 visability of designating such bladders as 'h\per- 

 tonic' has already been discussed. 



Neurophysiological and clinical descriptions are 

 not in sufficient rapport to permit a close correla- 

 tion. However, a few observations and predictions 

 leased on general neurophysiological information 

 provide a framework into which the clinical findings 

 might be profitably fitted. The initial stage of are- 

 flexia is the first of many parallels that can be drawn 

 between micturition and the myotatic reflex of 

 skeletal muscle on which posture is based. It is 

 probable that interruption of facilitation from 

 higher levels has rendered the local, or segmental, 

 afferent influx from the bladder insufficient to excite 

 the preganglionic sacral neurons. Expressed tech- 

 nically, these neurons, lying in the o\'erlap of de- 

 scending and segmental synaptic influences, pass 

 from the supraliminal field into the subliminal fringe 



