Hansen, H. C. and Lueck, C. J. and Crawford, T. J. and Kennard, C. and Zangemeister, W. H. (1993) Evidence for the occurrence of myotonia in the extraocular musculature in patients with dystrophia myotonica. Neuro-Ophthalmology, 13 (1). pp. 17-24.
Full text not available from this repository.Abstract
Dystrophia myotonica (DM) is a multisystem disorder which has been reported to affect eye movements. There is, however, disagreement in the literature as to whether the observed slowing of saccadic eye movements is due to a central abnormality or due to abnormalities of the extraocular muscles themselves. A ‘warm-up’ effect is well known to occur in the peripheral muscles in DM. This effect involves a progressive decrease in the degree of myotonia observed with each successive relaxation during a period of repetitive contraction and relaxation of a given muscle. The authors have studied seven patients using two different paradigms to provide evidence that the ‘warm-up’ phenomenon can be demonstrated in extraocular musculature in patients with DM. Such an effect is not seen in controls. The observation of a ‘warm-up’ phenomenon suggests that the disorder of saccadic eye movements is likely to be due to an abnormality of the extraocular muscles themselves rather than a central mechanism.