Discussions:

Comment

ECOG based epilepsy surgery for cortical scarring
Basant Pant, Prabin Shrestha, Pranaya Shrestha, Pravesh Rajbhandari (Nepal

Congratulations! This presentation has confirmed that "indication" is
science, and operation is "technique"!

With best regards,
T. Doczi
Pecs, Hungary

Excellent presentation. May I ask what are your criteria for intractable epilepsy?

Many thanks

Nikolaos Tzerakis
Stoke-on-Trent, UK

Thanks for your comment Dr Tzerakis. we do not strictly follow any criteria of intractability although there are many
definitions. Most of the cases who come to us are already on 2-3 drugs for more than a year, but sometime even with one drug on adequate dose if the
seizure is not at all controlled and there is a definitive ictal onset zone, we go ahead with surgery early. By this we can cure them soon and they can
lead a normal life rather then waiting for long to get labelled as intractable. So it is actually a case by case decision and we are getting bolder on our
decision as the time progress. Thanks

Basant Pant, MD
Kathmandu, Nepal

Question

ECOG based epilepsy surgery for cortical scarring
Basant Pant, Prabin Shrestha, Pranaya Shrestha, Pravesh Rajbhandari (Nepal )

Nice presentation. Congratulations.

My question:
What would be the reason for persistent seizures with selective amygdalo-hippocampectomy?
Would it be some unrecognized neocortical lesion? Interested to know what was the re-surgery performed, the result and whether resected neocortex suggested any lesion.
It is interesting to observe that ganglioglioma removal did not resolve seizures. Did ECoG suggest any spikes from hippocampus in this case?

Of course there are plenty of unanswered mysteries in pathogenesis of refractory seizures and ECoG is definitely a useful tool in planning resections in selected cases.

In mesial temporal sclerosis, it is interesting to note that resected neocortex not uncommonly shows up some pathology- dysplasia/ granuloma/ low grade tumor, which was not recognized preoperatively.

Question:
Would it be right to consider mesial temporal sclerosis is the effect of refractory seizures on hippocampus and not the cause?

regards
Komal Prasad
Bangalore, India

Comment

Indeed, the question of whether hippocampal neuronal loss with gliosis, commonly if erroneously called “medial temporal sclerosis”, “Ammon’s Horn Sclerosis”, and similar terms, is a cause of temporal lobe epilepsy or an effect of chronic temporal lobe epilepsy has a long history and remains unresolved. It is likely that the truth is more nuanced; that in many cases seizures are initiated by some neocortical lesion (tumor, microdysgenesis, inflammation, contusion) and that the hippocampal damage is secondary to the seizures, but that in some cases the only pathological lesion is the hippocampal damage and this may be the primary inciting lesion in those cases. Of interest, resection of a temporal lesion causing seizures in patients who have hippocampal damage may result in continued seizures because, whether primary or secondary initially, the abnormal hippocampus can be a further generator of seizures unless it is also resected.

The question of why some patients continue to seize after hippocampectomy is also complex as has been said here by others, but when there is “dual pathology” such as cortical dysplasia, excess white matter neurons, or marked microglial activation and proliferation it is likely that temporal lobectomy with amygdalohippocampectomy still leaves behind other epileptogenic architectural or structural lesions, or a pro-epileptic inflammatory state in which seizures may be driven by cytokines from activated microglia.

Douglas C Miller
Columbia, Missouri, USA

Question

There is an interesting work from Argentina; Dr Pomataet al have reported revision of cases that simulated to have temporal seizures but they were intraoperatively registered and found Insular foci that propagate electrical abnormal activity to temporal lobe or frontal very early. Have you seen this kind of findings in your clinic?

Jaime Diegoperez
Mexico City

Answer

Yes, I have seen a few cases presented in which invasive monitoring documented insular seizure foci which appeared only to be temporal with external EEG recordings. Of course I only looked at the pathology of these cases, others did the neurosurgery, but I always looked at the MRIs and did my best to understand the epileptologists’s readings of the EEGs and invasive monitoring.

DCM

Douglas C Miller
Columbia, Missouri, USA

(The e-mail address to contribute your questions and comments is: neurosurgeryresearch@jiscmail.ac.uk)

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