Vascular factors in carpal tunnel syndrome.

An increase in hand and forearm volume was induced without hand movement in ten subjects who had carpal tunnel syndrome (CTS). A tester, unaware of sides affected by CTS, performed the Volume Provocation Test (VPT) by inflating a sphygmomanometer cuff around the upper arm to 15 mm Hg less than diastolic pressure for four minutes. Pre- and post-test volumes, intensity of discomfort, and quality and distribution of produced symptoms were recorded. The VPT induced significant increases of segment volumes bilaterally (P1 tailed <0.05), but not more on the side of strongest symptoms compared to the less affected, or asymptomatic side (P1 tailed = 0.07). Mean discomfort on the side of strongest symptoms (5.4/10) was significantly higher (P1 tailed <0.01) than on the contralateral side (2.4/10). In 44% of the affected arms, some or all of the subjects' nocturnal symptoms were reproduced after volume increase, suggesting that CTS is a vascular phenomenon in these patients.