DETRUSOR-SPHINCTERIC DYSSYNERGIA IN PARAPLEGICS COMPARED WITH THE SYNERGIA IN A BRAIN-DEAD HUMAN BY USING THE SINGLE-FIBER ACTION-POTENTIALRECORDING METHOD
G. Schalow et al., DETRUSOR-SPHINCTERIC DYSSYNERGIA IN PARAPLEGICS COMPARED WITH THE SYNERGIA IN A BRAIN-DEAD HUMAN BY USING THE SINGLE-FIBER ACTION-POTENTIALRECORDING METHOD, Journal of the autonomic nervous system, 52(2-3), 1995, pp. 151-180
(1) Humans with spinal cord lesions often show detrusor-sphincteric dy
ssynergia of the urinary bladder which is reflected urodynamically in
the detrusor pressure and a simultaneous increase in electromyographic
pelvic floor activity. (2) The time-course of the increase in the sec
ondary muscle spindle afferent activity, induced by the parasympatheti
c nervous system in muscle spindles contributing to continence, is ver
y similar to that of detrusor pressure. The detrusor-sphincteric dyssy
nergia is therefore analysed by comparing the natural impulse patterns
of secondary muscle spindle afferents (SP2) and sphincteric motoneuro
ns in a brain-dead human with those in patients with spinal cord lesio
n. The parasympathetic nervous system was activated by painful bladder
catheter pulling. (3) In a brain-dead human the sphinteric motoneuron
s subserving continence were inhibited at a time, when preganglionic p
arasympathetic efferents increased their activity for 10 s and an SP2
fibre increased its activity for several minutes. In a paraplegic with
a strong bladder dysfunction, the SP2 fibre activity increased, due t
o parasympathetic activation, lasted for approx. 1 min, showed undulat
ions and its amplitude was smaller than that measured in a brain-dead
human. The sphincteric motoneurons were not inhibited. (4) In the brai
n-dead human, an SP2 fibre showed doublet firing with interspike inter
vals (IIs) of a duration between 10 and 14 ms for low level parasympat
hetic activation. For high level parasympathetic activation this singl
e parent spindle afferent fibre showed multi-ending regular firing of
up to 6 endings with IIs of a duration of predominantly 15 to 25 ms. I
n one paraplegic with a strong bladder dysfunction the doublet firing
was less regular, even though two II peaks at 10.2 and 11.2 ms occurre
d in a II distribution similar to the brain-dead human. The multi-endi
ng regular firing was replaced by a repeated burst firing. In a second
paraplegic with strong detrusor-sphincteric dyssynergia the burst fir
ing consisted of up to 6 impulses with increasing IIs and a first II o
f approx. 0.2 ms (transmission frequency 5000 Hz). In a third parapleg
ic with a lesser dysfunction of the bladder a highly activated SP2 fib
re showed an activity pattern intermediate to those of multi-ending re
gular firing and burst firing. (5) The time constant for the activity
decrease of a spindle afferent fibre following parasympathetic activat
ion was to 31 s in a paraplegic and approx. 40 s in a brain-dead human
. It is concluded that the muscle spindles are unchanged following spi
nal cord lesion. The pathologic firing patterns of the SP2 fibres are
thus a result of neuronal network changes in the parasympathetic nervo
us system of the sacral micturition center. (6) Differences in axon me
mbrane properties between animals and humans, simultaneous action of t
he somatic and the parasympathetic divisions, the detrusor-sphincteric
coordination, hyperreflexia and clinical implications are discussed.