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The testing of evoked potentials is of the greatest utility in detecting subclinical spinal cord and optic nerve lesions. Up to two-thirds of persons with multiple sclerosis have neurologic deficits that are evident on visual or personal somatic evoked potentials but not on physical examination. A "second lesion" of this type frequently establishes the diagnosis of multiple sclerosis. Evoked potentials may be abnormal in the other conditions listed in the question. Ref - Harrison's internal medicine 20e pg 3191-3192, 3192t, 3193f,
Brainstem involvement in stroke
A clinically occult lesion in multiple sclerosis
Large hemispheral strokes
Spinal cord compression
C.N.S