The following article posted in Pediatric Rheumatology, may be useful for detecting disease activity.
Sonographic evaluation of pediatric localized scleroderma:  preliminary disease assessment measures
Li et al. Pediatric Rheumatology 2010, 8:14 

This article provides characteristics presented in 3 cases of en coup de sabre and stresses the importance of a thorough medical examination when symptoms such as these exist. Linear Scleroderma en coup de sabre With Associated Neurologic Abnormalities, Pediatrics Vol. 117 No.1 Jan. 2006, pp. e132-e136 http://pediatrics.aappublications.org/cgi/content/full/117/1/e132