THE PHYSIOPATHOLOGV OF EPILEPTIC SEIZURES 



353 



of somatomotor or occipital strychnine epilepsy under 

 the facilitating effect of a bombardment of afferent 

 ' influx' coming from the corresponding sensory areas 

 [the epilepsy of Amantea (8) and of Clementi (28, 29), 

 described on p. 355]. This led Moruzzi to write: 

 "When, in the photic epilepsy of Clementi, we il- 

 luminate the retina, we not only send nervous im- 

 pulses into the striate area which has been strych- 

 ninized, but at the same time we activate the whole 

 of the cerebral cortex through the ascending reticular 

 formation of the brain stem." The generalized seizure 

 that follows is presumably subcortical since subse- 

 quent ablation of both somatomotor areas does not 

 prevent the convulsions from developing (9). It is 

 therefore most likely that any discharge of partial 

 epilepsy, once it is of sufficient magnitude, can be 

 transmitted to the centrencephalic structures from 

 the thalamus to the medulla, and from there be gen- 

 eralized to the rest of the brain. 



There is supporting EEG evidence for these conclu- 

 sions. Jasper el al. (108) showed that the majority 

 of cortical postdischarges are transmitted to the 

 reticular formation of the thalamus and brain stem. 

 French et al. (50) demonstrated a .subcortical reticular 

 mechanism in generalized postdischarges provoked by 

 localized cortical stimulation. "Surface regions dis- 

 playing the characteristic local response (persistent 

 after discharge) seem to have the capacity secondarily 

 to excite certain diffu.sely projecting subcortical struc- 

 tures (reticular formation, septal region and amyg- 

 dala) which are capable of disseminating the induced 

 discharge widely." Finally, in microphysiological 

 studies in strychnine epilepsy, von Baumgarten et al. 

 (190) have shown that each strychnine spike developed 

 in the motor cortex alters the spontaneous activity of 

 the neurons of the reticular formation so that their 

 activity is momentarily reinforced; this effect must 

 play a large part in the phenomenon of generalization. 



EXPERIMENTAL PARTIAL EPILEPSY WITH ERRATIC DIS- 

 CHARGES. In some cases, a seizure of partial epilepsy 

 stops as suddenly as it starts, the postictal electrical 

 silence appearing simultaneously in all the discharg- 

 ing structures. In other cases, however, the discharge 

 comes to an end in one formation and is transmitted 

 at the same time to another more or less distant part, 

 thus prolonging the seizure. This phenomenon was 

 first described by McCulloch & Dusser de Barenne in 

 '935 C'39) with reference to electrical postdis- 

 charges in animals anesthetized with diallyl bar- 

 bituric acid. Walker & Johnson (192), studying the 



same phenomenon, showed that in the normal 

 monkey localized postdischarges stop abruptly, 

 whereas in the monkey with an experimental epilepto- 

 genic lesion they are transmitted froin one cortical 

 region to another and continue for several minutes. 

 McCulloch (138) reinvestigated the question, with 

 seizures provoked by chlorophenothane (DDT) and 

 other poisons and particularly in a case of status 

 epilepticus in a monkey with an experimental frontal 

 epileptogenic lesion. He describes how the epileptic 

 discharge would appear at one point on the cortex, 

 disappear and suddenly reappear at an unforeseen 

 spot, like a 'jack-in-the-box'. Gastaut & Roger (78) 

 studied multiple and successive cortical seizures fol- 

 lowing stimulation of the amygdaloid nucleus. They 

 showed that these 'surprise' discharges do not really 

 arise independently in different parts of the cortex, 

 but that they represent one and the same discharge 

 transmitted from a certain point on the cortex to 

 allied subcortical structures and from there to other 

 cortical regions. It was only in 1953 that Gastaut et al. 

 (75, 76) demonstrated in man the existence of multi- 

 ple cortical discharges probably corresponding to this 

 same mechanism of 'erratic' propagation. Since 

 then, the Marseilles workers have constantly empha- 

 sized that these erratic discharges are frequent and 

 especially significant in so-called 'psychomotor' 

 epilepsy. 



Anatomical Studies 



Patients with partial epilepsy usually harbor con- 

 spicuous organic cerebral lesions, in contrast to those 

 cases in which the seizure is generalized from the 

 start. In cases of partial epilepsy with a single somato- 

 motor or sensory symptom related to the pre- or post- 

 rolandic, occipital or superior temporal regions, a 

 lesion in that particular area is usually demonstrable 

 anatomically as well as electrographically. The most 

 frequent lesion is a cicatrix or atrophy, and much more 

 rarely a neoplasm. The lesion is usually superficial 

 and involves only the cortex locally (a corticomenin- 

 geal scar or localized cortical atrophy), but some- 

 times it goes deeper and is not seen on inspection of 

 the exterior of the brain. 



In polysymptomatic partial epilepsy, however, with 

 the sensory, mental and motor manifestations of 

 psychomotor epilepsy, true focal lesions are usually 

 not seen. The lesions on the contrary are remarkably 

 diffuse in these patients. The most frequent lesion is 

 corticosubcortical atrophy with more or less well- 



