Video demonstrates the difficulty in opening the eyes after forced eye closure that can be seen in patients with myotonic disorders. Eye-closure myotonia is seen most frequently in patients with sodium channel mutations. The patient is instructed to squeeze his eyes shut tightly and then open them as quickly as possible. The maneuver can be repeated to check for evidence of warm-up or paradoxical worsening.
Richard J. Barohn, MD, FAAN
CONTINUUM: Lifelong Learning in Neurology. 19(6, Muscle Disease):1598-1614, December 2013