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After-discharge activity as a basis to change intraoperative mapping protocol for functionally significant brain areas


Background. After-discharge (AD) activity is a pattern that differs from background corticography, represented by rhythmic stereotypical slow waves and/or repetitive spike discharges with ≥1 Hz frequency, recorded after cessation of electrical stimulation and lasting for more than 2 seconds. Despite the accumulated experience in the field of intraoperative neuromonitoring, there is no unified protocol for high-frequency stimulation of cortical functional areas (FAs) upon the AD event.

Objective: to demonstrate a need to change the intraoperative FAs mapping protocol in patients with brain tumor on awakening in cases of AD recording.

Material and methods. Two clinical cases of awake surgical functional mapping followed by resection of the brain tumor are presented. Multimodal monitoring included high-frequency stimulation according to the approved intrahospital protocol with maximum stimulation force of auditory-speech zones of 2.5 mA, electrocorticography, and subcortical dynamic mapping.

Results. In the first case, AD was registered while FAs mapping in a patient with a history of one epileptic seizure, upon reaching the maximum stimulation force of 2.5 mA, that was replaced by recording focal epileptiform activity with the following evolution to ictal generalized event and development of intraoperative convulsive seizure. In the second patient with a history of recurrent epileptic seizures, AD with spatiotemporal evolution of the pattern development of clinical ictal event was registered with stimulation at 2.5 mA. In both cases, the appearance of AD required to change mapping protocol with a stepwise decrease in stimulus strength to obtain cortical FAs data.

Conclusion. Registration of AD is the basis for changing the protocol of high-frequency cortical stimulation in surgical treatment of brain tumor FAs.

About the Authors

M. G. Podgurskaya
Medsi Clinic
Russian Federation

Maria G. Podgurskaya – Neurologist, Functional Diagnostician

1 bldg 2 3rd Khoroshevskiy Dr., Moscow 123007

D. S. Kanshina
Research Institute of Emergency Pediatric Surgery and Traumatology
Russian Federation

Daria S. Kanshina – MD, PhD, Senior Researcher, Department of Functional Diagnostics

22 Bolshaya Polyanka Str., Moscow 119180

A. V. Dimertsev
Pirogov National Medical and Surgical Center
Russian Federation

Aleksey V. Dimertsev – Laboratory Assistant, Department of Neurosurgery, Head of Educational Unit, Department of Neurosurgery

70 Nizhnyaya Pervomayskaya Str., Moscow 105203

M. V. Alexandrov
Almazov National Medical Research Center
Russian Federation

Mikhail V. Alexandrov – Dr. Med. Sc., Professor, Head of Department of Clinical Neurophysiology, Head of Laboratory of Clinical Research in Neurosurgery and Neurology

2 Akkuratov Str., Saint Petersburg 197341

S. S. Nikitin
Bochkov Medical and Genetic Research Center
Russian Federation

Sergey S. Nikitin – Dr. Med. Sc., Professor, Chief of Chair of Genetics of Neurological Diseases

1 Moskvorechye Str., Moscow 115478


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For citations:

Podgurskaya M.G., Kanshina D.S., Dimertsev A.V., Alexandrov M.V., Nikitin S.S. After-discharge activity as a basis to change intraoperative mapping protocol for functionally significant brain areas. Epilepsy and paroxysmal conditions. 2023;15(1):36-43. (In Russ.)

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ISSN 2077-8333 (Print)
ISSN 2311-4088 (Online)