Clinical applications of evoked responses: a survey

Evoked responses were first described in the late forties. In the late fifties, technology had so far advanced that the method became practically useful in clinical applications. Descriptions of the normal response and the influence of age and the effect of attention were extensively studied. There are marked interindividual and interlaboratory differences, partly explained by differences in test set-up. This is why it is still necessary that every laboratory, using its own test set-up, should determine its own standard values in normal test subjects. The value of ER studies in clinical diagnosis may be summarized as follows: --ophthalmology, organic psychiatry, neuropaediatrics, multiple sclerosis, uraemia: ER studies often supply important diagnostic information; --local lesions of the cerebral hemispheres, peripheral nerves and spinal cord, coma: ER studies can be useful as source of supplemental diagnostic information; --non-organic psychiatry and psychology: ER studies are still of minor practical value in individual clinical diagnosis. Research into applications of spinal evoked potentials and brain stem potentials is still in its initial phase.