THE PHYSIOPATHOLOGY OF EPILEPTIC SEIZURES 



351 



cephalic formations (56, 72, 80, 81, 83, 122, 132, 150). 

 The clinical manifestations are of interest. Stimulation 

 of the hippocampus or gyrus fornicatus provokes a 

 simple reaction of ' attention' and contralateral 'ori- 

 entation' of the head when the stimulus is of weak 

 intensity. When a stronger stimulus is applied, it pro- 

 vokes more complex reactions suggestive of anxietv, 

 fear or anger. In every case, the animal shows some 

 lack of awareness and responds little or not at all to 

 outside influences. This impaired responsiveness con- 

 trasts with the accompanying portrayal of 'arrest' and 

 'attention' and is paradoxical if one interprets it as 

 the expression of clouded consciousness. The paradox, 

 however, disappears if one thinks that it reflects ex- 

 tremely concentrated attention on an abnormal psy- 

 chological event created by the stimulation, perhaps 

 an illusion or a hallucination. 



Stimulation of the piriform cortex, or the under- 

 lying amygdala, provokes complex phenomena in 

 which are associated: /) contraversive deviation which 

 may or may not be accompanied by abnormal tonic 

 or clonic movements; 2) complex gestures apparently 

 reactive to abnormal sensations involving the bucco- 

 facial region or the extremities (licking the lips, clear- 

 ing the throat as though to get rid of a foreign body, 

 or lifting and shaking a paw); j) actions with a feed- 

 ing significance (lapping, mastication, salivation or 

 deglutition); and ./) changes in the autonomic, re- 

 spiratory and circulatory spheres, including pupillary 

 changes, micturition and defecation. 



The electroencephalographic efifect of electrical 

 stimulation of the rhinencephalon has been studied 

 by Gastaut et al. (72, 80, 81, 84), Gloor (90), and 

 Feindel & Gloor (46), who investigated chiefly the 

 amygdala, and by Kaada (119, 121), Creutzfeldt & 

 Meyer-Mickeleit (32), and Andy & Akert (10, 11) 

 who studied the hippocampus particularly. In these 

 studies postdischarges were produced which involved 

 the structure stimulated (amygdala or Amnion's 

 horn) and were transmitted to: /) the homologous 

 contralateral region; 2) allied structures such as the 

 hypothalamus, the septum and the anterodorsal 

 thalamus; 3) the corpus striatum and midbrain 

 tegmentum; 4) the pyriform cortex, the orbito- 

 insulotemporal cortex and secondarily the anterior 

 part of the gyrus cinguli; and 5) sometimes even to 

 the rest of the isocortex. There is considerable diff'er- 

 ence of opinion among authors as to propagation to 

 the isocortex, which according to some is predom- 

 inantly to the frontal regions and according to others 

 to the occipital regions. 



Propagation to these structures may be either si- 

 multaneous or successive, and Gastaut et al. (72, 80, 

 83) particularly stress the fact that the postdischarges 

 are erratic, and that they may be transmitted, for 

 example, from the amygdala to the temporal and 

 septal regions, then to the posterior hypothalamus and 

 from there to the frontal cortex, returning again to 

 the temporal region. 



6) Local application or injection of aluminum cream. 

 Stereotaxic techniques have made it possible to pro- 

 duce epileptogenic scars in the same limbic or basal 

 rhinencephalic structures. The experimental results 

 closely resemi^le those of electrical stimulation (81, 

 83, 84). 



The clinical manifestations are typically seizures 

 which occur 2 or 3 mo. after injection of aluminum 

 hydroxide into the amygdaloid nucleus. The following 

 description of seizures in cats is given by Naquet(i5o): 

 "The animal suddenly changes its attitude, some- 

 times tries to escape, becomes anxious, immobile, then 

 sniflfs violently, especially to the side of the amvgdaloid 

 scar; at the same time one notes pupillary dilatation, 

 clonic movements of the homolateral eyelids, rapidly 

 followed by facial hemispasm with deviation of the 

 head to the opposite side, clonic masticatory move- 

 ments and salivation. The seizure may stop at this 

 stage, or else the cat lifts its anterior contralateral paw 

 and there appear clonic movements of the whole of 

 the contralateral side of the body followed by a gen- 

 eralized fit with urinary incontinence. A ' confusional' 

 state with loud miaowing follows the seizure. In some 

 cases, there are in addition various types of seizures 

 which are predominantly 'psychological'. Suddenly 

 the animal becomes immobile, its pupils dilate, its be- 

 havior changes, it lifts its contralateral paw as though 

 to defend or attack, there is marked piloerection and 

 it bites if one tries to touch it. This seizure lasts 20 to 

 40 sec. and suddenly the animal becomes aflfectionate 

 again. Alternatively, the animal suddenly tries to 

 escape, miaows fiercely, its pupils dilate and its be- 

 havior gives the impression that it sees or hears some- 

 thing alarming. This seizure terminates rapidlv." 



The electroencephalographic manifestations will 

 now be described. Between seizures, one observes 

 sporadic discharges of slow waves, of spikes or spike- 

 and-wave complexes at the periphery of the amygda- 

 loid, hippocampal or septal lesions, which are trans- 

 mitted to one or several of the following regions: 

 uncus, insula, tip of the temporal lobe, temporal lobe 

 proper, posterior orbital region (78, 84, 167). These 

 discharges may be on the same or the opposite side 

 of the lesion and sometimes may even predominate 



