Bladder abnormalities due to injury of motor pathways in the nervous system L. G. Lewis, O. R. Langworthy and J. E. Dees. Journal of the American Medical Association, 1935.
Little was known about the nervous innervation of the bladder in 1935. A constellation of symptoms and a number of deficits were attributed to injuries to the sensory pathways of the bladder. While two motor pathways were described: one from the cerebral cortex and one from the midbrain (the pontine micturation center), the subsequent deficits were not well understood.
To investigate the motor innervation of the bladder, Lewis, Langworthy and Dees create a precursor to the modern cystometrogram (urodynamics) - a relatively simple device made of a catheter and manometer filled with water and coupled to a recording device (see figure). The authors catalogue the findings in a normal patient a demonstrate low-pressure filling and a normal sensation at around 200cc of water.
The authors then investigate and describe the outcomes of patients with three distinct patterns of voiding:
- Bilateral cortical lesions (lesion #1) - leading to a small capacity bladder and involuntary contractions.
- Unilateral cortial lesions (lesion #2) - patients with left-sided lesions had normal bladder capacity, those with right-side lesions had decreased bladder capacity leading the authors to believe that bladder control was heisphere-dominant.
- Spinal cord injuries (lesion #3) - these patients demonstrated a variety of findings, all of which demonstrated abnormal filling, volumes and contractions.
- Normal micturition depends on a steady rise of bladder pressure of sufficient strength and duration to empty the viscus completely. When waves occur rhythmically and frequently, they do not have the strength or duration for efficient emptying.
- The cerebral cortex controls the smooth muscle of the bladder, enabling the bladder to hold large amounts of fluid at a relatively low pressure (below the level of discomfort). Without conrtical control, bladder capacity decreases and frequency of urination is common.
- Many of the frequency and urgency symptoms following neurologic injury can be considered as uninhibited smooth muscle reflexes (analagous to a "knee-jerk" reflex).
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