Reversible Horner's syndrome and dysthyroid ocular myopathy associated with Hashimoto's disease.

BACKGROUND Although it has been frequently stated that thyroid disease induces Horner's syndrome, there have been few reports describing the anatomical relation of goiter to the cervical preganglionic sympathetic nerve fibers in acquired Horner's syndrome, which is identified by the eye-drop test for adrenergic sensitivity. CASE A 40-year-old woman with Hashimoto's disease presented with vertical diplopia, and blepharoptosis and miosis on the left side. OBSERVATIONS Computed tomography scan showed hypertrophy of the right inferior rectus muscle, which resulted from a dysthyroid process, causing the limitation of upward movement of the right eye. The eye-drop test for adrenergic sensitivity revealed that only the left pupil dilated significantly after administration of 5% tyramine, and the Mueller's muscle on the left side did not respond. These results suggest that Horner's syndrome was due to a preganglionic sympathetic lesion. Magnetic resonance imaging (MRI) of the neck showed chronic inflammatory lesions in both lobes of the thyroid gland identified by a high-intensity signal. CONCLUSION The reconstruction technique of MRI demonstrated that the swollen left lobe of the thyroid gland was compressing the pathway of the cervical preganglionic sympathetic nerve fibers.