Memory loss and memory reorganization patterns in temporal lobe epilepsy patients undergoing anterior temporal lobe resection, as demonstrated by pre-versus post-operative functional MRI

ABSTRACTObjectiveLow-Intensity Focused Ultrasound Pulsations (LIFUP) is a promising new potential neuromodulation tool. However, the safety of LIFUP neuromodulation has not yet been adequately assessed. Patients with refractory temporal lobe epilepsy electing to undergo an anterior temporal lobe resection present a unique opportunity to evaluate the safety and efficacy of LIFUP neuromodulation. Because the brain tissue in these patients will be removed, histological changes in tissue after LIFUP can be examined. Evidence of effective neuromodulation was assessed using functional MRI and EEG, while further potential safety concerns were assessed using neuropsychological testing.MethodsEEG, functional MRI, and neuropsychology were assessed in six patients before and after focused ultrasound sonication of the temporal lobe at intensities up to 5760 mW/cm2. Using the BrainSonix Pulsar 1002, LIFUP was delivered under MR guidance, using the Siemens Magnetom 3T Prisma scanner. Neuropsychological changes were assessed using various batteries. EEG was recorded using the Electrical Geodesics EGI 256 channel system. Histological changes were assessed using hematoxylin and eosin staining, among others.ResultsLIFUP was not able to modulate the BOLD signal on fMRI in a reliable and consistent manner. The EEG data that was available did not demonstrate a change in activity after LIFUP in all but one subject. Likewise, the neuropsychology testing did not show any statistically significant changes in any test, except for a slight decrease in performance on the one test after LIFUP. Lastly, the histology did not reveal any detectable damage to the tissue, except for one subject for whom the histology findings were inconclusive.SignificanceThe safety in the histology was the primary endpoint, and as such, longer exposure at the highest intensity levels will be administered moving forward.Key PointsLIFUP is a novel brain stimulation technique with not yet fully established safety guidelines.LIFUP was administered to patients electing to undergo resective brain surgery.LIFUP does not appear to cause damage to tissue.Longer exposure times are needed to further show safety at these intensity levels.

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Semantic memory is impaired in patients with unilateral anterior temporal lobe resection for temporal lobe epilepsy

Brain ◽

10.1093/brain/awr325 ◽

2012 ◽

Vol 135 (1) ◽

pp. 242-258 ◽

Cited By ~ 102

Author(s):

M. A. Lambon Ralph ◽

S. Ehsan ◽

G. A. Baker ◽

T. T. Rogers

Keyword(s):

Temporal Lobe Epilepsy ◽

Semantic Memory ◽

Temporal Lobe ◽

Anterior Temporal Lobe ◽

Temporal Lobe Resection

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Resective surgery prevents progressive cortical thinning in temporal lobe epilepsy

Brain ◽

10.1093/brain/awaa284 ◽

2020 ◽

Vol 143 (11) ◽

pp. 3262-3272

Author(s):

Marian Galovic ◽

Jane de Tisi ◽

Andrew W McEvoy ◽

Anna Miserocchi ◽

Sjoerd B Vos ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Healthy Volunteers ◽

Temporal Lobe ◽

Epilepsy Surgery ◽

Focal Epilepsy ◽

Cortical Atrophy ◽

Anterior Temporal Lobe ◽

Cortical Thinning ◽

Temporal Lobe Resection ◽

Normal Ageing

Abstract Focal epilepsy in adults is associated with progressive atrophy of the cortex at a rate more than double that of normal ageing. We aimed to determine whether successful epilepsy surgery interrupts progressive cortical thinning. In this longitudinal case-control neuroimaging study, we included subjects with unilateral temporal lobe epilepsy (TLE) before (n = 29) or after (n = 56) anterior temporal lobe resection and healthy volunteers (n = 124) comparable regarding age and sex. We measured cortical thickness on paired structural MRI scans in all participants and compared progressive thinning between groups using linear mixed effects models. Compared to ageing-related cortical thinning in healthy subjects, we found progressive cortical atrophy on vertex-wise analysis in TLE before surgery that was bilateral and localized beyond the ipsilateral temporal lobe. In these regions, we observed accelerated annualized thinning in left (left TLE 0.0192 ± 0.0014 versus healthy volunteers 0.0032 ± 0.0013 mm/year, P < 0.0001) and right (right TLE 0.0198 ± 0.0016 versus healthy volunteers 0.0037 ± 0.0016 mm/year, P < 0.0001) presurgical TLE cases. Cortical thinning in these areas was reduced after surgical resection of the left (0.0074 ± 0.0016 mm/year, P = 0.0006) or right (0.0052 ± 0.0020 mm/year, P = 0.0006) anterior temporal lobe. Directly comparing the post- versus presurgical TLE groups on vertex-wise analysis, the areas of postoperatively reduced thinning were in both hemispheres, particularly, but not exclusively, in regions that were affected preoperatively. Participants who remained completely seizure-free after surgery had no more progressive thinning than that observed during normal ageing. Those with postoperative seizures had small areas of continued accelerated thinning after surgery. Thus, successful epilepsy surgery prevents progressive cortical atrophy that is observed in TLE and may be potentially neuroprotective. This effect was more pronounced in those who remained seizure-free after temporal lobe resection, normalizing the rate of atrophy to that of normal ageing. These results provide evidence of epilepsy surgery preventing further cerebral damage and provide incentives for offering early surgery in refractory TLE.

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