There is something quite significant going on here. Removal of lobes of the brain for epilepsy and breastfeeding in infants (as opposed to artificial feeding) are the only two interventions known to me that permanently raise IQ. Any other candidates?

it depends on exactly what outcome you are looking for. Studies have proved the benefits on cognitive performances following lesionectomy in epilepsy especially temporal lobectomy or hippocampectomy. Similarly with space demanding lesions, there is better seizure control if not total cessation of seizures as well as better cognitive abilities in affected patients. However there are some lesionectomies that are not beneficial like cerebellar surgeries.

I mean lesionectomy - targeted removal of a pathological focus - not lobectomy. We have observe that it may influence positively neurological functions, such as motor function, fine movement control, or speech. The focus sometimes lies at a distance to the cortical representations of these functions, meaning that the effect is not due to mere decompression. One hypothesis is that the focus causes inhibitory effect, mediated via neural networks. This explains why Its removal leads to improvement within short time after surgery.

Thanks for clarification. Hippocampectomy or temporal lobectomy may be considered lesionectomy if and when you can demonstrate hippocampal sclerosis or mesial temporal sclerosis in patients, thus the sclerosed tissue is a pathological lesion so in a way you perform lesionectomy. Anyhow on the targeted removal of a pathological focus it is true that it results in improved neurological function. we have studied cognitive functions before and after and observed improved cognitive performances suggesting that neurological effects of these lesions occur at remote sites apart from the direct compression effects. we have noted this in patients with meningiomas, pituitary tumors (in absence of hormonal derangements) and low grade gliomas.

yes. Aa seizures come down ,the harmful effects of repeat seizures can be preveted and inturn has a beneficial effect on neural function

Let me point you to an article recently published by the neurosurgery department of Geneva University Hospitals, Switzerland, that focused on neuropsychological outcomes following extra-temporal lobe resections. An interesting finding is that neuropsychological improvement did not depend strictly on seizure freedom.

El Hassani Y, Fournet M, Momjian S, Pollo C, Seeck M, Pegna A, Schaller K.

Neuropsychological outcome after extra-temporal epilepsy surgery.

Acta Neurochir (Wien). 2012 Aug;154(8):1337-42.

http://dx.doi.org/10.1007/s00701-012-1379-0.

Of note, neuropsychological improvement following surgery in children with severe epilepsy of early onset is not systematic and depends on multiple factors. Cf. Roulet-Perez E, Davidoff V, Mayor-Dubois C, Maeder-Ingvar M, Seeck M, Ruffieux C, Villemure JG, Deonna T. Impact of severe epilepsy on development: recovery potential after successful early epilepsy surgery. Epilepsia. 2010 Jul;51(7):1266-76. http://dx.doi.org/10.1111/j.1528-1167.2009.02487.x.

Thanks Pierre, this is good. the observations of the authors were similar to what we noted in our patients. I agree that the cognitive improvements were not dependent on seizure control per se, though it thus appear that there is a marginal benefit among those who had better seizure control post surgery. here are the doi for the article.

You may want to read papers on paradoxical functional facilitation (PFF). For a nice review see Kapur, Brain 1996. Some have reported PFF after TBI and cerebellar stroke.

That said, the big question is whether there is longitudinal data before and after lesionectomy to support the view that the lesion improved a specific function.