Pattern shift visual evoked response in carotid occlusion.

Pattern shift visual evoked response (PSVER) latency has been shown to be an extremely sensitive but nonspecific measure of optic nerve dysfunction. The test has been most useful in detecting unsuspected demyelinating lesions of the optic nerve, but abnormal results have been reported in a variety of other conditions affecting the optic nerve, including ischemic optic neuropathy. We report a patient with left internal carotid artery occlusion, possibly secondary to neck trauma, with normal ophthalmological examination and abnormal PSVER. The suggested mechanism is subclinical optic nerve ischemia due to decreased blood flow in the ophthalmic artery. PSVER may have value as a sensitive indicator of internal carotid artery disease.