162 AJMONE-MARSAN
Setup for the study of seizure patterns (details in text). Kristof Abraham performs the Metrazol
activation while EEG technologist Barbara Lightfoot assists. In the background is chief EEG
technologist Maureen Benson-DeLemos (also trained at the MNI), at the camera control and
EEG recording equipment (not shown)
Donated to the Office of NIH History by Dr. Cosimo Ajmone-Marsangiven patient, a careful comparison study was carried out to confirm such
an assumption.^15 For this purpose, the patterns of each ictal episode (spon
taneous and induced) and their temporal sequence were transformed
into “formulas” for a better qualitative and quantitative comparison. By
this method, it was possible to accept as quite reliable and specific the
large majority of induced seizures. No examples of incorrect lateralization
were encountered. The main difference between the two types of seizures
was the higher tendency for the induced ones to generalize quickly into
major tonic-clonic episodes. The occasional induction of a purely grand
mal convulsion only led to the conclusion that the activating technique
had been of no use for localizing or lateralizing purposes in that patient.
On the basis of these studies it was possible to analyze the variety of
seizure patterns and the characteristic pathway of spread from differ
ent original foci (see fig. 1), in a large number of subjects with more or
less faithful scalp or direct cortical or depth EEG correlations.^16 Begin
ning in 1955, these studies were carried out, when specifically indicated,
in parallel with the use of invasive recording procedures (see above).