Vertical pendular nystagmus in chronic myositis of medial and lateral rectus.

A 38-year-old white woman developed left medical rectus myositis possibly due to an immune response to mepivacaine (Carbocaine) injected around her upper left first molar. Ten months after resolution, a recurrence of left medial restus myositis and also left lateral rectus myositis occured after the injection of chemically related lidocaine (Xylocaine) in the same area. At this time, with gaze to the left, there appeared vertical pendular nystagmus of greater amplitude in the involved eye, in the absence of systemic neurologic or posterior fossa disease. This association of vertical pendular nystagmus with chronic myositis of the medial and lateral rectus, to my knowledge, has not been previously reported.