Extension of an excellent pilot study to a quantitative analysis of the pathophysiology of de Quervain disease associated with colonoscopy

To the Editor:

In the article by Shergill et al,1 they analyze right thumb pinch force using a thumb-force sensor applied to the right thumb and analyze muscle activity of left and right forearm muscles using electromyography during colonoscopy. They report that activity of the left abductor pollicis longus muscle during colonoscopy exceeds the American Conference of Industrial Hygienists, hand activity level action limit. This finding supports that excessive, repeated abduction and extension of the left thumb during colonoscopy to manipulate the turn dials of the colonoscope may cause de Quervain disease (tenosynovitis of the left thumb), as I2 and others3, 4 have previously clinically reported.

An association between de Quervain disease of the left thumb and colonoscopy may be further confirmed by extending their experiments to include left thumb strain measurements (as they report for the right thumb), with the colonoscope held with the left hand outside a patient (as they report during actual colonoscopy on a patient), during maximal colonoscope tip deflection of both turn dials applied by the left thumb, and while recording subjective sensations of left thumb strain.