An experimental study on compression neuropathy--the vulnerability of the peripheral nerve associated with pregnancy

The carpal tunnel syndrome often occurs in women associated with pregnancy and menopause, but its pathophysiology is not well understood. The author proposes a hypothesis that the peripheral nerve is vulnerable in pregnancy to become an important cause for the carpal tunnel syndrome. This study was designed to test the hypothesis by using "Keio compression device" for sciatic nerve of a dog using the compression force of 27.6 mmHg/cm2. No remarkable changes were found in the pregnant group before compression. In the control group, a delay of motor nerve conduction velocity was seen three weeks after compression. In contrast, the conduction block at compression site occurred in more than half of pregnant group under an equal compression force, inducing severe histological changes. This study demonstrates an increase of the vulnerability of the peripheral nerve in pregnancy. A disturbance of the blood-nerve barrier as well as the changes of hormones and vitamins could influence this phenomenon.