Metrazol Activation as a Diagnostic Adjunct in Electroencephalography

Abstract

Metrazol activation studies were made on 250 subjects. Of these, 120 met strict criteria of normality. Eighty-one patients were diagnostic problems with equivocal epileptoid symptoms and/or abnormal eegs., and 49 were definite convulsive cases having non-diagnostic electrographic findings. Results for the latter two groups are comparable with those reported in the literature. Fifty-four % of normal controls under the age of 30 gave a positive response, and 62% of these were spike and wave type. Of 61 normals over the age of 30, 16.4% showed a positive response. Thus, age seems to be an extremely important factor in determining electrographic response to Metrazol. None of the normal group showed focal abnormalities with Metrazol. The slow technique was, however, very effective in activating focal abnormalities in the abnormal group. The effect of different techniques on the results is discussed. Data is presented suggesting that regardless of the technique used paroxysmal spike and wave patterns can be produced with a low dosage of Metrazol in individuals with a negative history for convulsions, negative family history, and no related symptomatology. Within limits, wt. did not seem to influence our results. It is well known that convulsions can be induced in anyone with appropriate stimulation. The assumption was made that there is a group ("epileptics") with an increased susceptibility, that is, with a low threshold of activation. Furthermore, the classic 3/sec. spike and wave pattern was almost universally accepted as a sign by which the epileptic may be differentiated from his "normal" brother. Yet, by the use of Metrazol, spike and wave can be elicited in a high percent of normal controls as well as in epileptics and with little correlation in regard to threshold. The spike and wave pattern is apparently elaborated by a mechanism which many of us, perhaps all possess; why some have seizures and others do not would appear to be due to something other than the simple ability to produce a certain type of electrical discharge pattern. With regard to whether the test can be used in the diagnosis of epilepsy, our results suggest that it would be diagnostically valid when it gives a focal response, as no such responses were produced in our normal group. On the other hand, a generalized paroxysmal response, even when it is a spike and wave pattern, cannot reasonably be considered reliable evidence of a convulsive disorder. These findings are discussed in relation to the problem of the use of chemical activation as a diagnostic technique in clinical eeg.