Ocular neuromyotonia. A clinical description of six patients
W. T. Shults, W. F. Hoyt, M. Behrens, J. MacLean, R. F. Saul and J. J. Corbett
We report the cases of six patients with ocular neuromyotonia, a disorder
believed to result from episodic involuntary discharge of ocular motor
nerves producing sustained and inappropriate contraction of their
respective ocular muscles. Transient disturbances of ocular motility and
diplopia result. Four patients had involvement of ocular muscles supplied
by the third cranial nerve: one had presumed involvement of the superior
oblique muscle, and one the lateral rectus muscle, suggesting abnormal
discharge in the fourth and sixth cranial nerves, respectively. Four of six
patients received prior radiation therapy for pituitary tumors, implying a
possible pathogenic link. Three patients improved after treatment with
membrane-stabilizing medication, suggesting that unstable membranes of
injured ocular motor axons may generate spontaneous impulses, which produce
involuntary sustained and inappropriate ocular muscle contraction.
