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Successful epilepsy surgery for tuberous sclerosis complex evaluated by stereoelectroencephalography Volume 22, issue 5, October 2020

TEST YOURSELF

(1) Are tuberous sclerosis patients with focal epilepsy and multiple tubers suitable candidates for epilepsy surgery?

 

(2) Should all tubers with frequent interictal discharges and electrographic seizures be removed to achieve seizure freedom?

 

(3) In patients with seizures arising either within or in close proximity to eloquent cortex, what procedures could be performed to achieve optimal seizure outcome with minimal neurological deficits?

 

 

 

 

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Answers

(1) This is a very specialised area of epilepsy surgery. In most instances, epilepsy surgery assessments are not straight forward in patients with TS; patients have multifocal or generalised seizures and behavioural challenges, and non-invasive investigations are not sufficiently localising. In selected tuberous sclerosis patients, despite non-invasive evaluation not definitively determining the epileptogenic lesion, targeted SEEG evaluation of multiple tubers based on hypothesized anatomo-electro-clinical analysis can be successful in identifying the potential epileptogenic tuber. Compared with invasive strips or grids, SEEG also has the added advantage of evaluation of the networks between the superficial cortex with the deeper cortical structures.

 

(2) Epileptogenicity differs among different cortical tubers. To determine the culprit epileptogenic tuber responsible for the patient’s intractable epilepsy, SEEG evaluation of clinical seizure correlation with an EEG electrographic seizure is important to direct resective surgery for best outcome. In our patient, prior to AED withdrawal, all clinical seizures were localised to the tuber at the right pre and post-central gyrus (Y,S electrodes). Only when the patient was weaned off AEDs did the electrographic seizure discharge from E’ activate the Y,S electrodes which subsequently triggered the clinical seizures. No spontaneous seizures were triggered solely from E’. We thus decided that the Y and S electrodes were the primary epileptogenic zone and proceeded with resection to only this tuber.

 

(3) Intraoperative electrocorticography is useful to assist in guiding resection margins and also evaluate the completeness of resection. In selected patients, as in our patient, awake craniotomy can provide an additional benefit by ensuring that eloquent function is not affected during resection.

 

 

 

 

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