Answers to Case 1-3-3
1. The motor supply to the bladder is parasympathetic via the pelvic plexus nerve
roots S 2,3,4. The sympathetic nerves originate in the thoracolumbar spinal cord
between T10 and L2 and may mediate bladder relaxation. Sensory nerves via C
and A d fibres carry afferent information from the bladder and travel with both
the parasympathetic and sympathetic nerves.
2. The site of the disruption dictates the effects on the bladder:
a. Suprapontine – loss of voluntary control but coordination is retained i.e.
coordinated relaxation of sphincter with detrusor contraction.
b. Sub-pontine but Supra-sacral – discoordinated voiding or detrusor sphincter
dyssynergia.
c. Sub-sacral – hypo-contractile detrusor.
Figure1-3-3a is an axial T2-weighted MRI in a young male patient showing
thickening and trabeculation of the bladder wall with a number of small diverticula.
This is typical of a patient with a neuropathic bladder, but similar changes
may also be seen with other longstanding causes of outfl ow obstruction.
Figure1-3-3b is a sagittal T2-weighted MRI of the lumbar spine that shows a
large expansible lesion arising from the distal cord compatible with myxopapillary
ependymoma of the conus. This is sub-pontine but supra-sacral in location,
and accounts for the bladder appearances on the MRI study. This was the cause
of the patient’s neuropathic bladder.
3. The main arterial supply to the bladder arises from the inferior vesical artery,
with some further and variable supply from the superior vesical artery. Both arise
from the anterior trunk of the internal iliac artery. Such is the contralateral collateral
supply that ligation or embolisation of a whole internal iliac artery is possible
with very little risk of ischaemia. Figure1-3-3 is an AP view from a pelvic
angiogram in which the anterior division of the left internal iliac is demonstrated.
This was embolised (images not shown) to stop intractable haematuria in a
patient with post-radiotherapy telangiectasia, in whom all other treatments had
failed. Note the numerous small corkscrew vessels (arrows) compatible with
telangiectasia.