inability to relax the hand grip - symptom common to all forms of myotonia
12/30/77: 34 year old man with myotonia dystrophia showing white opacities in the posterior cortex and a congenital lamellar type pf opacity around the fetal nucleus of the lens. Noteworthy in the muscular system is a marked weakness of the face so that he is unable to furrow his forehead and there is a marked weakness of the orbicular despite the fact that he has a slight amount of ptosis. There is also marked myotonia of his grip.
David G. Cogan, MD (1908-1993), Former Director of Ophthalmology, National Eye Institute
U.S. Department of Health and Human Services. National Institutes of Health. National Eye Institute