External ophthalmoplegia due to ocular myositis in a patient with ophthalmic herpes zoster.

External ocular muscle palsies in patients with ophthalmic zoster are traditionally interpreted as diseases of III, IV or VI cranial nerves. Orbital myositis associated with zoster ophthalmicus has been diagnosed only rarely. We describe a patient with ophthalmic zoster and external ophthalmoplegia due to ocular myositis demonstrated by MR imaging. Treatment with acyclovir and cortisone resulted in a rapid improvement of the ophthalmoplegia. In ophthalmic herpes zoster associated with external ocular muscle palsies, ocular myositis is an important differential diagnosis to inflammatory involvement of the cranial nerves III, IV, and VI.