Novel tonometer device distinguishes brain stiffness in epilepsy surgery

Aria Fallah*, Thirusivapragasam Subramaniam, H. Westley Phillips, Xavier Michalet, Harry V. Vinters, William H. Yong, Joyce Y. Wu, Noriko Salamon, Benjamin M. Ellingson, Anthony C. Wang, Samuel D. Reyes, George M. Ibrahim, Alexander G. Weil, Julia W. Chang, Diana Babayan, Jimmy C. Nguyen, Eric Behnke, Chi Hong Tseng, Gary W. Mathern

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Complete surgical resection of abnormal brain tissue is the most important predictor of seizure freedom following surgery for cortical dysplasia. While lesional tissue is often visually indiscernible from normal brain, anecdotally, it is subjectively stiffer. We report the first experience of the use of a digital tonometer to understand the biomechanical properties of epilepsy tissue and to guide the conduct of epilepsy surgery. Consecutive epilepsy surgery patients (n = 24) from UCLA Mattel Children’s Hospital were recruited to undergo intraoperative brain tonometry at the time of open craniotomy for epilepsy surgery. Brain stiffness measurements were corrected with abnormalities on neuroimaging and histopathology using mixed-effects multivariable linear regression. We collected 249 measurements across 30 operations involving 24 patients through the pediatric epilepsy surgery program at UCLA Mattel Children’s Hospital. On multivariable mixed-effects regression, brain stiffness was significantly associated with the presence of MRI lesion (β = 32.3, 95%CI 16.3–48.2; p < 0.001), severity of cortical disorganization (β = 19.8, 95%CI 9.4–30.2; p = 0.001), and recent subdural grid implantation (β = 42.8, 95%CI 11.8–73.8; p = 0.009). Brain tonometry offers the potential of real-time intraoperative feedback to identify abnormal brain tissue with millimeter spatial resolution. We present the first experience with this novel intraoperative tool for the conduct of epilepsy surgery. A carefully designed prospective study is required to elucidate whether the clinical application of brain tonometry during resective procedures could guide the area of resection and improve seizure outcomes.

Original languageEnglish (US)
Article number20978
JournalScientific reports
Issue number1
StatePublished - Dec 2020
Externally publishedYes

ASJC Scopus subject areas

  • General


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