Video demonstrates the clinical evaluation of percussion myotonia over the extensor digitorum communis. A fast strike with the reflex hammer over the extensor digitorum communis produces the characteristic extension of the fingers and wrist, with subsequent myotonic catch and delay of muscle relaxation.
Richard J. Barohn, MD, FAAN
CONTINUUM: Lifelong Learning in Neurology. 19(6, Muscle Disease):1598-1614, December 2013