Table 3.

The physics of visceral myopathy

Megacystis (massive bladder dilation) and pathological bowel dilation (in CIPO) can be modeled using Laplace’s law (Fig. 3).

Laplace’s law: wall tension is proportional to intraluminal radial pressure and radius and is inversely proportional to wall thickness.

With increased bowel and bladder distension (radius), greater wall tension is required to maintain intraluminal pressure.

Distension causes a decrease in wall thickness, necessitating even more wall tension to maintain intraluminal pressure.

Cytoskeletal mutations that impair force generation and transmission will also reduce the maximum wall tension that can be developed by the bowel and bladder. Bowel and bladder distension are likely progressive and irreversible as weakened SMCs in bowel and bladder are unable to generate the wall tension necessary to resist distension.

CIPO, chronic intestinal pseudo-obstruction; SMC, smooth muscle cell.