F- CLINICAL ASPECTS OF SPINAL CORD INJURIES
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of the superior hypogastric plexus. Conversely, following resection of the plexus or the
upper lumbar ganglia, the power of ejaculation is abolished or at least greatly impaired,
while bladder function remains unimpaired.
2.
The parasympathetic innervation
originates in 82, 3 and 4 segments and reaches the
bladder and urethra through the pelvic autonomic rami (nervi erigentes). It represents
the chief efferent mechanism in the act of micturition. Stimulation of the pelvic nerves
always results in vigorous contraction of the detrusor muscle. Unilateral stimulation of
the pelvic nerve elicits strong contraction of the ipsilateral side of the detrusor but also,
although diminished, contraction of the opposite detrusor. Stimulation of the central
end of a severed pelvic nerve, while that of the opposite side remains intact, causes
contraction of the whole bladder after a latent period of a few seconds (Ingersoll
et al.,
1955). Conversely, resection of the pelvic nerves results in flaccid paralysis of the
bladder.
3.
Somatic volitional innervation
originates in Si and 82 segments and reaches the striated
musculature of the urethra and pelvic floor through the pudendal nerves. Stimulation
of the pudendal nerves elicits elevation and closure of the vesical neck (Ardran
et al.,
1956; Noix, 1960). Pudendal anaesthesia (Lapides
et
a/., 1955) or pudendal neurotomy
does not result in incontinence (Wertheimer & Michon, 1928).
B. AFFERENT INNERVATION
Afferent impulses mediating sensation of bladder distension and pain is conveyed by the
pelvic and pubic nerves but also by the sympathetic innervation. Afferent impulses
arising from the bladder are conducted through the pelvic nerves, while those arising
from the external sphincter and partly also from the vesical neck travel through the
pudendal nerves. However, Bors (1952) concluded from his experience with transurethral
resection of the bladder neck that pain can still be experienced in spite of complete
anaesthesia resulting from pudendal nerve block. According to Learmonth (1931), pain
and touch sensations are conveyed by parasympathetic and sympathetic fibres. In
Denning's (1924) animal experiments with bladder distension, the uneasiness of the
animal caused by bladder distension was not relieved by pudendal neurectomy but was
greatly diminished following resection of the pelvic and hypogastric nerves.
Although the parasympathetic afferents mediate sensation of bladder distension and
pain, sympathetic afferents also convey these sensations in complete spinal cord lesions
above the level of the transection (Guttmann & Whitteridge, 1947). The findings of
Langworthy
et al.
(1940) that the bladder is sensitive to thermal stimuli are not in
accordance with the results of other authors (Waltz, 1922; Nathan, 1952), and it is
suggested that the disagreement regarding thermal sensibility of the bladder is due to
associated thermal stimulation of the urethra which is actually sensitive to thermal
stimulation.
